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THE 


APPLIED  ANATOMY  OF  THE 
NERVOUS  SYSTEM 


BEING  A  STUDY  OF  THIS  PORTION  OF  THE  HUMAN  BODY  FROM  A 

STANDPOINT  OF  ITS  GENERAL  INTEREST  AND  PRACTICAL 

UTILITY   IN  DIAGNOSIS,    DESIGNED    FOR    USE   AS 

A   TEXT-BOOK  AND  A  WORK  OF  REFERENCE 


BY 

AMBROSE   L.   RANNEY,  A.  M.,  M.  D. 

Professor  of  the  Anatomy  and  Physiology  of  the  Nervous  System  in  the 

New  York  Post-Graduate  Medical  School  and  Hospital ; 

Pi'ofessor  of  Nervous  and  Mental  Diseases  in  the  Medical  Department  of  the  University  of  Vermont; 

Late  Adjunct  Professor  of  Anatomy  and  Lecturer  on  the  Diseases  of  the  Genito-Urinary  Organs  and 

on  Minor  Surgery  in  the  Medical  Department  of  the  University  of  the  City  of  New  York ; 

Late  Surgeon  to  the  Northern  and  Northwestern  Dispensaries; 

Resident  Fellow  of  the  New  York  Academy  of  Medicine ; 

Member  of  the  Medical  Society  of  the  County  of  New  York ; 

Member  of  the  Neurological  Society  of  New  York ; 

Author  of  a  "  Practical  Treatise  on  Surgical  Diagnosis,"  "'  Practical  Medical  Anatomy," 

"  Electricity  in  Medicine,"  "  The  Essentiala  of  Anatomy,"  etc. 


SECOND   EDITION 
REWRITTEN,  ENLARGED,  AND  PROFUSELY  ILLUSTRATED 


"  The  greatest  thing  a  human  soul  ever  does  In  this  world  is  to  see  somethhig,  and  tell  what 
he  saw  in  a  plain  way.  Hundreds  of  people  can  talk  for  one  that  can  think,  but  thousands  can 
think  for  one  who  can  see.    To  see  clearly  is  poetry,  prophecy,  and  religion  all  in  one  " 

John  Ruskin 


NEW  YORE 

D.     APPLETON    AND    COMPANY 

1888 


tx 


CoPYMOHT,  1881,  1888, 
By  D.  APPLETON  AND  COMPANY. 


®o  tl)e  iHemors  of 

LAFAYETTE  RANNEY,   A.  M.,  M.  D., 

THIS   VOLUME 
18  DEDICATED    BY    HI8    SON, 

THE  AUTHOR. 


o  <*>  *" 


PREFACE  TO  THE  SECOND  EDITIOK 


The  author  lias  been  prompted  by  the  many  favor- 
able reviews  of  the  first  edition  of  this  work,  and  by  its 
general  adoption  as  a  text-book,  to  modify  its  scope  and 
plan,  with  a  view  of  rendering  it  more  worthy  of  com- 
mendation. It  is  hoped  that  its  field  of  usefulness  will 
be  materially  enhanced  by  the  alterations  made. 

The  changes  have  been  so  radical  that  the  present  edi- 
tion may  be  said  to  be  practically  a  new  work.  The  sec- 
tion on  the  brain  has  been  entirely  rewritten,  in  order  that 
the  latest  discoveries  in  the  anatomy  and  physiology  of  that 
organ  should  be  comprised  within  its  pages.  The  sections 
on  the  cranial  nerves  and  the  spinal  cord  have  also  been 
enlarged,  and  so  altered  as  to  make  them  more  comprehen- 
sive in  their  scope.  Some  cuts  of  the  former  edition  have 
been  discarded,  and  better  ones  selected  as  substitutes. 
Many  new  diagrams  have  been  designed  by  the  author  to 
illustrate  the  text. 

A  work  upon  this  field  must,  of  necessity,  be  to  a  large 
extent  a  discussion  of  others'  views.  Originality  of  treat- 
ment of  the  subject  may  possibly  be  claimed  for  this  vol- 
ume (because  diagrammatic  illustration  forms  an  important 
feature  in  the  author's  system  of  teaching) ;  but  no  work 


vi  PREFACE  TO   THE  SECOND  EDITION. 

upon  this  field  can  be  complete  without  frequent  allusion? 
to,  or  quotations  from,  the  valuable  contributions  of  the 
more  prominent  neuro-anatomists,  pathologists,  and  physi- 
ologists, m 

The  new  matter  incorporated  in  this  edition  as  well  as 
much  of  the  old  edition  contains  frequent  references  to 
the  writings  of  many  authors,  and  it  is  hoped  that  their 
respective  views  are  now  correctly  and  impartially  stated 
at  all  times.  Great  care  has  been  exercised  in  giving  full 
credit  to  those  to  whose  original  work  the  author  owes 
much  of  the  valuable  information  here  gathered  into  one 
volume. 

The  aim  of  the  author  has  been  to  furnish  a  reliable 
guide  to  the  student  of  neurological  anatomy  and  physi- 
ology, in  which  he  may  find  the  views  of  the  leading 
minds  in  that  field  accessible,  and  the  main  facts  which  are 
applicable  to  diagnosis  clearly  interpreted.  It  is  still  pos- 
sible that  oversights  in  acknowledgment  may  have  oc- 
curred, as  is  very  apt  to  happen  in  a  work  of  this  kind 
(since  it  is  but  a  publication  of  lectures  delivered  before 
classes  of  students),  but,  if  so,  they  are  unintentional  and 
open  to  correction. 

Much  of  the  new  matter  of  this  edition  has  already  ap- 
peared in  various  medical  journals,  among  which  may  be 
mentioned  the  *^  New  York  Medical  Journal,"  the  "  Medical 
Kecord,"  the  "  Journal  of  Nervous  and  Mental  Diseases," 
and  the  "Archives  of  Medicine."  Some  of  these  lectures 
have  received  the  unexpected  honor  of  a  French  and  Ital- 
ian translation. 

In  the  preface  to  the  first  edition  the  author  expressed 
his  incentive  to  the  effort,  as  well  as  his  doubts,  as  follows : 

"  The  rapid  strides,  which  are  being  made  in  the  inter- 
pretation of  the  symptoms  of  nervous  diseases,  and  the  in- 


PREFACE  TO   THE  SECOND  EDITION.  vii 

troduction  of  many  new  terms,  wliicli  must  embarrass  the 
reader  of  late  monographs,  unless  he  be  educated  to  the 
present  standard  of  knowledge  in  this  field  of  medicine, 
seem  to  the  author  a  reasonable  ground  for  belief,  that  there 
is  a  demand  for  a  volume,  which  shall  fit  the  practitioner 
and  student  to  pursue  his  studies  in  this  special  line  with- 
out embarrassment,  if  not  with  increased  interest. 

"  With  whatever  merits  or  demerits  the  volume  may 
possess,  I  intrust  it  to  the  public,  conscious  that  an  effort 
to  clear  up  a  field  made  obscure  by  visionary  theories  and 
endless  speculation  can  not  but  contain  some  ground  to 
which  exception  may  be  taken.  To  what  extent  it  will 
supply  the  place  of  a  guide  in  this — the  labyrinth  of  medi- 
cal science — experience  alone  must  decide." 

Finally,  the  acknowledgments  of  the  author  to  the  pro- 
fession (who  have  decided  in  his  favor  by  giving  the  first 
edition  of  this  work  their  support  in  spite  of  its  many  im- 
perfections) are  now  in  place.  It  will  be  his  aim  to  make 
subsequent  editions,  if  called  for,  more  complete  than  the 
present  one. 

Ambrose  L.  Ranney. 

156  Madison  Avenfe,  New  York  City, 
March,  1888. 


TABLE   OF   OONTEISTTS. 


PAOBS 

GENERAL  INTRODUCTION    .....  1-21 

The  NEEV0U8  system  oonsideeed  as  a  whole. 
Its  component  parts. 
The  general  axioms  of  nerve  distribution. 


PART  I. 

THE  BRAIN    .......       21-327 

The  cerebro-spinal  axis. 

Histological  elements  of  nervous  steuotubes. 

Varieties  of  nerve  currents: 

Centripetal  or  sensory. 

Centrifugal  or  motor. 
Functions  of  nerve  cells  and  nerve  fibers: 

Isolated  conduction  of  impulses. 

Generation  and  storage  of  nerve  force. 

Discharge  of  nerve  force. 

Storage  of  various  forms  of  memories. 

Consciousness  and  mental  processes. 
Gray  matter  of  brain: 

The  cortex  cerebri. 

The  basal  ganglia  of  cerebrum. 

The  cortex  cerebelli. 

The  tubular  gray  matter. 

The  corpora  quadrigemina. 

The  gray  matter  of  pons  and  medulla. 

The  various  smaller  ganglia. 
The  cerebrum  .  .  .  .  \  .      27-122 

White  matter  of  cerebrum: 

The  commissural  fibers. 

The  peduncular  fibers. 

The  associating  fibers. 

The  fornix  fibers. 
The  projection  systems  of  Meynert  and  Spitzka: 

Reasons  for  such  an  arrangement. 


TABLE  OF  CONTENTS. 


General  formation  of  projection  systems. 

Cranial  nerve  tracts. 
The  cerebral  cortex: 

Its  general  construction,  color,  thickness,  etc. 

Its  connective  tissue  (neuroglia). 

Its  layers  and  their  special  peculiarities. 

Modifications  of,  in  different  regions. 

The  seat  of  all  mental  processes  and  volition. 
Topography  of  cerebral  cortex: 

Arrangement  of  its  lobes,  lobules,  fissures,  and  sulci. 

The  classification  of  its  convolutions  (Ecker). 
Functions  of  cerebral  cortex: 

The  centers  of  motion. 

Motor  center  of  speech  (Broca). 

Centers  of  hearing,  sight,  smell,  taste,  touch,  etc. 

Aphasia,  as  a  symptom. 

The  motor  area,  and  its  subdivisions. 

Cortical  motor  paralysis. 

Sensory  areas  of  the  cortex  and  their  functions. 
Occipital  lobes. 

Parietal  lobes  (posterior  to  motor  area). 
Temporo-sphenoidal  lobes. 
Symptoms  referable  to  cortical  lesions: 

Monoplegia;  early  rigidity;  localized  pain;  Jacksonian  epi- 
lepsy; hemianopsia;  word-blindness;  word-deafness;  motor 
aphasia;  paraphasia;  mono- anaesthesia;  monospasm;  abo- 
lition of  memories  of  various  kinds ;  hallucinations  of  vision ; 
vomiting;  choked-disk,  etc. 
Summary  of  the  physiology  of  the  cerebral  cortex: 

Its  excitable  regions. 

Its  physiological  centers. 

Views  respecting  cerebral  localization. 

Classification  of  the  various  monoplegias. 

Discrimination  between  destructive  and  irritative  lesions  of 
the  cortex. 

The  storage  of  various  forms  of  memories. 

Results  of  widely  diffused  lesions  of  the  cerebral  cortex. 
Weight  and  growth  of  the  brain: 

Relative  development  of  component  parts. 

Rapidity  of  growth  during  different  periods  of  life. 
Intra- cerebral  lesions  : 

General  statements  respecting  them. 
Surgical  bearings  of  cerebral  topography: 

Guides  to  the  more  important  cortical  centers  of  cerebrum. 

Late  observations  of   Horsley  respecting    the    motor   cen- 
ters. 

Thane's  method  of  locating  Rolando's  fissure. 

Guides  to  the  fissure  of  Sylvius. 

Indications  and  contra-indications  for  trephining. 


TABLE  OF  CONTENTS.  xi 


Diagnostic  symptoms  of  intea-oerebeal  lesions: 

Profound  coma;  hemiplegia;  heraianaesthesia;  late  post-para- 
lytic rigidity ;  tremor ;  hemichorea ;  athetosis ;  general  con- 
vulsions ;  impairment  of  special  senses ;  choked-disk,  etc. 
The  corpus  striatum         .....     122-132 
Nuclei  of  coepus  striatum. 
Theie  clinical  and  physiological  impoetance. 
Fusion  of  the  caudate  and  lenticulae  nuclei. 
Cells  of  each  nucleus. 
Lenticular  nucleus: 

Its  shape,  situation,  and  relations. 
Its  fibers. 

Its  three  members  (Glieder). 
Caudate  nucleus: 

Its  shape  and  relations.  . 
Its  cell  groups. 

Its  afferent  and  efferent  fibers. 
Peobable  functions  of  the  C0EPU8  striatum. 
The  optic  thalamus  .....     132-151 

The  ganglia  associated  with  the  thalamus. 
The  shape  and  eelative  development  of  the  thalamus. 
Its  anterior  and  posterior  tubercles. 
Its  surfaces  and  their  relations  to  adjacent  parts. 
The  fibers  associated  with  the  thalamus. 
Probable  functions  of  the  thalamus: 

Ferrier's  views;  Luys's  thalamic  centers;    Ritti's  views  re- 
specting hallucinations;  the  relations  of  the  thalamus  to  the 
optic  fibers  and  the  main  sensory  conducting  paths,  etc. 
The  gray  lining  of  the  third  ventricle: 

Inferior  optic  ganglion ;   substantia  innominata  of  Reil ;  an- 
terior pillar  of  fornix;  bundle  of  Vicq  d'Azyr,  etc. 
The  interj^al  capsule       .....     151-172 
Relations   of    the   capsule   to    the    basal    ganglia   of    the 

cerebrum. 
Subdivisions  of  the  component  bundles  of  the  capsule  : 
Caudo-lenticular  fibers;  facial  bundle;  general  motor  tract; 
general  sensory  tract;  speech  tract;  optic  fibers,  etc. 
Methods  of  research  of  Turck,  Waller,  Flechsig,  and  Gudden. 
Origin,    course,    and   terminations   of   the   more   important 

bundles  of  the  internal  capsule. 
Diagnostic  symptoms  of  lesions  of  the  internal  capsule: 
Varieties  of  lesions  encountered;  hemiplegia;  heraianaesthesia; 
choked-disk;    tremor;    athetosis;    impairment  of    special 
senses;  conjugate  deviation  of  the  eyes;  choreiform  move- 
ments, etc. 
The  corpora  quadrigemina  ....     172-200 

The  anterior  and  posterior  pair. 
The  brachia  and  their  eelations. 


xu 


TABLE  OF  CONTENTS. 


Functions  of  antkbior  paib. 

Relations  of  these  bodies  to  the  visual  sense: 

Hemianopsia ;  probable  ganglia  of  the  visual  apparatus ;  intra- 
cranial lesions  which  may  affect  sight ;  tests  for  hemianopsia ; 
varieties  of  hemianopsia;  paralysis,  coexisting  with  hemia- 
nopsia ;  psychical  blindness ;  cortical  area  of  vision ;  crossed 
paralysis  coexisting  with  hemianopsia. 
The  crura  cerebri  ..... 

The  cbusta  obubis  ob  motob  pobtion. 
The  tegmentum  obubis  ob  sensoby  pobtion. 
The  substantia  nigba. 

The  ganglia  of  obigin  of  the  tegmental  fibebs. 
The  postebiob  longitudinal  fasciculus. 
The  lemniscus  tbact. 
The  fobmatio  beticulabis. 
Fibebs  of  the  supebiob  cebebellab  peduncle. 
Fibebs  fbom  the  post-optic  ganglion. 
The  geniculate  bodies. 
The  bed  nuclei  of  Stilling. 
The  mamillaey  tubebcle. 
The  pineal  gland. 
The  cerebellum      ...... 

Geneeal  anatomy  and  belations  of  the  cebebellum. 
Cobtex  of  the  cebebellum. 
White  substance  of  the  cerebellum. 
Pbojection  systems  of  cerebellum. 

Gray  masses  indibectly  connected  with  the  cebebellum: 
Red  nuclei  of  Stilling  in  the  tegmentum. 
Olivary  bodies  of  the  medulla. 
Ganglia  of  the  pons  Varolii. 
Peduncles  of  the  cerebellum: 
Processus  ad  cerebrum. 
Processus  ad  pontem. 
Processus  ad  medullum  (restiform  body). 
Relations  of  cerebellum  to  cranial  nerves. 
Pbobable  functions  of  the  cebebellum: 

An  organ  of  coordination ;  relations  to  visual  perceptions ;  re- 
lations to  tonic  muscular  contractions;  views  of  Mitchell, 
Spencer,  Spitzka,  and  others. 
Diagnostic  symptoms  of  cebebellab  lesions: 

Cerebellar  ataxia;  vertigo;  titubating  gait;  staggering;  gas- 
tric crises;  anarthria;  occipital  pain;  nystagmus;  ambly- 
opia; choked-disk;  amaurosis;  rotary  movements,  etc. 
The  pituitary  body  .  .  .  .  . 

Its  general  appearance  and  construction. 
The  medulla  oblongata  and  pons  Varolii     . 
FoBM  and  fissubes  of  medulla. 
Subdivisions  of  medulla  (Krause). 


200-216 


216-243 


243,  244 
244-307 


TABLE  OF  CONTENTS.  xiii 


Changes  in  gray  matter  from  that  of  spinal  cobd,  due  to 

formation  of  fourth  ventricle. 
The  gray  matter  of  the  medulla  and  pons: 
Cranial  nerve  nuclei. 
Accessory  nerve  nuclei. 
Superadded  gray  matter. 
Reticular  ganglion  (Spitzka). 
Upward  continuation  of  the  anterior  horns  of  the  spinal 
cord: 

Nucleus  of  the  pyramid ;  nuclei  of  lateral  column ;  hypoglossal 
nucleus ;  abducens  nucleus ;  motor-oculi  nucleus. 
Upward  continuation  of  the  posterior  horns  of  the  spinal 
cord: 
Substantia  gelatinosa ;  reticular  ganglion. 
Upward  continuation  of  the  central  gray  of  the  spinal 
cord: 

Posterior  spinal  accessory  nucleus ;  nuclei  of  ninth,  tenth,  and 
eleventh  cranial  nerves ;  lining  of  fourth  ventricle ;  aqueduct 
of  Sylvius. 
Accessory  nuclei  of  the  medulla: 

Inferior  facial  nucleus;  accessory  nuclei  of  the  spinal  acces- 
sory and  hypoglossal  nerves;  the  acoustic  nuclei. 
Superadded  gray   matter   of   the  medulla   and  pons  Va- 
rolii : 

Triangular  nuclei ;  clavate  nuclei;  olivary  bodies ;  parolivary 
bodies;  nuclei  of  the  pyramids;  middle  sensory  nucleus  of 
the  trigeminus;  red  nuclei  of  Stilling;  geniculate  bodies, 
etc. 
The  white  substance  of  the  medulla  and  pons: 

General  classification  of  the  fibers. 
The  pyramidal  tracts: 
Their  accessory  fibers. 
Their  course  and  function. 
Upward  continuation  of  the  anterioe  root  zones  of  the 
spinal  cord  : 

Fibers  of  the  formatio  reticularis;  posterior  longitudinal  bun- 
dles ;  portion  of  the  fillet  or  lemniscus  tract  (?). 
The  fillet  or  lemniscus  tracts  : 

Its  two  bundles — motor  (?)  and  sensory. 
Its  relation  to  motor-oculi  nerve. 
Its  relations  to  the  triangular  and  clavate  nuclei. 
Its  probable  function. 
The  direct  cerebellar  tracts: 

Association  with  the  vesicular  column  of  Clarke. 
The  probable  termination  of  these  fibers. 
Probable  function  of  these  fibers. 
Continuation  upward  of  Burdach's  and  Goll's  columns: 
The  nuclei  of  these  columns;  ascending  root  of  fifth  nerve; 
round  bundle  or  the  "  respiratory  bundle  "  (Krause). 


XIV 


TABLE  OF  CONTENTS. 


The  8EN80RT  TRACT8  TO  THE  CEREBRUM: 

Researches  of  Flechsig,  Voq  Monakow,  Starr,  etc. 

Reticular  formation. 

The  fillet  tract. 

Paths  for  sensations  of  pain,  touch,  and  temperature. 

Path  for  the  muscular  sense. 

Relations  of  these  paths  to  the  cerebellum. 

The  sensory  or  "  pinniform  "  decussation. 

The   SUPERADDED   FIBERS    OF   THE    PONS   AND   MEDULLA ! 

The  fibers  of  the   superior,  middle,  and  inferior  cerebellar 
pedungles. 

DlA-GNOSTIO   symptoms    of    LESIONS    OF   THE   PONS: 

Crossed  facial  paralysis ;  crossed  hemianaesthesia ;  anarthria ; 
convulsions;  conjugate  deviation  of  the  eyes;  contraction 
of  the  pupil ;  deafness ;  disturbances  of  respiration  and  cir- 
culation ;  unilateral  ataxia,  etc. 
Functions  of  the  medulla: 

A  great  reflex  ganglion ;  the  special  physiological  centers  situ- 
ated within  it ;  nervous  circle  of  deglutition ;  nervous  mech- 
anism of  respiration;  nervous  mechanism  of  circulation; 
vasomotor  center  of  the  medulla,  etc. 
Diagnostic  symptoms  of  lesions  of  the  medulla: 

Impairment  of  speech,  deglutition,  and  circulation;  diabetes; 
albuminuria;  loss  of  power  of  protrusion  of  tongue;  Du- 
chenne's  disease ;  bilateral  paralysis  of  arms  and  legs ;  uni- 
lateral ataxia;  vaso-motor  disturbances,  etc. 
The  ventkicles  of  the  brain     .... 

Their  general  situation,  shape,  formation,  and  ependyma. 
The  chief  commissures  of  the  brain^    . 
Corpus  callosum. 
The  fornix. 

Commissures  of  the  third  ventricle. 
The  membranes  of  the  brain     .... 
The  dura  mater. 
The  arachnoid. 
The  pia  mater. 
Blood-vessels  of  the  brIin         .... 
The  carotid  system  and  its  branches. 
The  vertebral  system  and  its  branches. 


307-31' 


314-316 


316-321 


321-327 


PART    II. 

THE   CRANIAL   NERVES        ..... 

Enumeration  of  the  nerves  from  before  backward. 

The  deep  origin  and  nuclei  of  the  twelve  separate  nerves. 
The  olfactory  nerve        ..... 

Its  origin  and  construction. 

The  peculiarities  of  its  filaments. 


329-533 


341-349 


TABLE  OF  CONTENTS. 


XV 


The  limits  of  its  disteibution. 

The  physiology  of  olfaction. 

The  act  of  sneezing. 

Reflex  acts  dependent  upon  the  olfactory  nerve. 

Functions  of  olfactory  nerve  in  animals. 

Relations  of  the  sense  of  smell  to  that  of  taste. 

Clinical  points  afforded  by  the  olfactory  nerve. 

"Hyperosmia,"  its  tests  and  causes;  "anosmia,"  its  tests  and 
causes. 
The  optic  nerve      ......    349-373 

The  optic  tracts,  their  origin  and  attachments. 
The  optic  chiasm,  its  construction  and  physiology. 
Distribution  of  optic  nerve. 
Reflex  acts  excited  by  optic  nerve 
Decussation  of  optic  fibers  and  its  physiology. 
Relations  of  the  optic  nerve  in  the  orbit.  , 

Anatomical  defects  of  vision  and  their  consequences. 
"Hyperopia,"  its  tests,  causes,  and  results;    "myopia,"  its 
tests,  causes,  and  results ;  "  astigmatism,"  its  tests,  causes, 
and  results. 
Changes  observed  in  the  pupil. 

Dilatation,  its  causes  and  physiology ;  contraction,  its  causes 
and  physiology. 
Visual  sensations  and  their  modifications. 

Muscse  volitantes ;  the  "  blind  spot "  of  the  retina ;  insensibil- 
ity of  the  retina  after  firm  pressure. 
The  perception  of  color. 

Visual  purple  and  its  probable  functions ;  rods  and  cones  of 
the  retina ;  Young-Helmholtz  theory  of  color  vision ;  limits 
of  different  color  perceptions ;  color  blindness. 
Apparent  vision  of  objects  not  really  seen. 

Its  causes. 
Effects  of  optic  nerve  on  coordination. 

Goltz's  experiments. 
Effects  of  optic  nerve  on  the  lachrymal  apparatus. 

The  act  of  winking  the  eyelid ;  effect  of  closure  of  eyelid  upon 
the  lachrymal  canals. 
Clinical  points  afforded  by  the  optic  nerve. 

Hemianopsia,   temporal,  its  causes;    hemianopsia,  nasal,  its 
causes ;  hemianopsia,  bi-nasal,  its  causes ;  hemianopsia,  bi- 
temporal, its  causes ;  amaurosis  ;  hyperaesthesia  of  the  optic 
nerve ;  amblyopia ;  atrophy  of  optic  nerve. 
The  motor-oculi  kerve      .  .  .  .  .    373-395 

Its  origin,  course,  and  distribution. 

The  physiology  of  contraction  of  the  pupil. 

Physiological  reasons  for   the   distribution   of  the  third 

NERVE. 

Mechanism  of  the  dilatation  of  the  pupil. 


xn 


TABLE  OF  CONTENTS. 


Movements  of  the  eyeball. 

Diagnostic  attitudes  of  the  head  in  ocular  paresis. 

Clinical  points  pertaining  to  the  third  nerve. 

Megalopsia  or  raacropsia;  micropsia;  ptosis;  motor-oculi  pa- 
ralysis ;  strabismus.    Diseases  of  the  ocular  muscles :  nystag- 
mus; iritic  spasm;  contracture;   paralysis;  tabetic  condi- 
tions; diplopia;  strabismus. 
The  trochlear  or  pathetic  nerve        .  .  .     395-397 

Its  superficial  and  deep  points  of  origin. 
Its  course  and  relations  within  the  cranium. 

Its  points  of  clinical  interest.  J 

The  trigeminus  nerve      .....     397-421 

Its  superficial  and  deep  points  of  origin. 

Course  of  its  sensory  and  motor  roots  within  the  cranium. 

Its  afferent  and  efferent  fibers. 

The  effects  of  section  of  the  nerve. 

On  sensation ;  on  mastication ;  on  taste;  on  hearing;  on  sight; 
on  smell. 
Clinical  points  pertaining  to  the  trigeminus  nerve. 

Neuralgia  (tic-douloureux) ;  spasm  of  the  trigeminus ;  paraly- 
sis of  its  individual  branches. 
Diagnostic  value  of  the  trigeminus  nerve. 

Bleaching  of  the  hair;  immobility  of  temporo-maxillary  joint; 
furring  of  the  tongue ;  ulceration  of  the  cornea ;  ulceration 
of  the  auditory  canal ;  earache ;  pain  in  the  scalp ;  conjunc- 
tival distribution. 
Surgical  anatomy  of  its  main  branches. 

Section  of  the  supra-orbital  nerve ;  section  of  the  supra-maxil- 
lary nerve ;  section  of  the  inferior-dental  nerve. 
The  ganglia  connected  with  the  trigeminus  nerve. 

Ophthalmic,  lenticular,  or  ciliary ;  spheno-palatine  or  Meckel's ; 
otic;  sub-maxillary. 
The  abducens  nerve  (motor-oculi  externus)  .  .     421-423 

Its  superficial  and  deep  points  of  origin. 
Its  relation  with  the  ophthalmic  ganglion. 
Its  clinical  relations. 
The  facial  nerve  ......     423-444 

Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
Physiology  of  its  main  branches. 

The  petrosal  nerves;  the  chorda  tympani  nerve;  the  "pars 
intermedia "  of  Wrisberg ;  the  tympanic  branch;  the  facial 
branches;  the  muscular  branches. 
Its  communications  with  other  parts. 

Branches  joining  the  fifth  nerve ;  branch  to  the  otic  ganglion ; 
branch  to  Meckel's  ganglion  ;  sympathetic  fibers ;  its  rela- 
tion to  deglutition  and  speech;  its  relation  to  smell;  its  re- 
lation to  hearing ;  its  relation  to  respiration. 


TABLE  OF  CON-TENTS. 


xvii 


Its  filaments  of  disteibutio]^. 

Physiological  relation  to  deglutition ;  physiological  relation  to 
facial  expression ;  physiological  relation  to  mastication. 
Clinical  points  peetaining  to  the  neeve. 

Spasm  of  the  facial  muscles.    Bell's  paralysis :  intra-cranial  va- 
riety ;  auditory  variety ;  rlieumatic  variety ;  traumatic  vari- 
ety; syphilitic  variety ;  diphtheritic  variety  ;  facial  diplegia. 
The  auditory  nerve  .....     444-466 

Its  supeeficial  and  deep  points  of  oeigin. 
Anatomical  steuctuee  and  peculiaeities  of  its  filaments. 
Its  couese  and  disteibution. 
Functions  of  its  vaeious  beanches. 
The  mechanism  of  audition. 

External  ear,  its  construction  and  functions ;  middle  ear,  its  con- 
struction and  functions.     Internal  ear,  its  construction  and 
functions :  the  semicircular  canals ;  the  vestibule.    The  coch- 
lea :  its  scalae ;  organ  of  Corti ;  membranes  and  ligaments. 
Clinical  points  peetaining  to  the  neeve. 

Auditory  vertigo — "  Meniere's  disease  " ;  injuries  to  the  semi- 
circular canals.     Neuroses  of  the  auditory  nerve :  acoustic 
hypersesthesia ;  acoustic  anaesthesia. 
The  GLOSSO-PHARYl^^GEAL  NERVE     ....      466-482 
Its  supeeficial  and  deep  points  of  oeigin. 
Its  ganglionic  enlaegements. 
Its  couese  and  eelations. 
Its  effeeent  oe  motoe  fibees. 
Its  affeeent  oe  sensoey  fibees. 
Its  fibees  of  taste. 
Effects  of  section  of  the  neeve. 

On  special  sense  of  taste ;  on  deglutition. 
Mechanism  of  the  act  of  deglutition. 

First  period ;  second  period ;  third  period ;  nerves  involved ; 
importance  of  soft  palate ;  the  nerve  center  for  the  act. 
Clinical  points  peetaining  to  the  neeve. 

Glosso-labio-laryngeal  paralysis — Duchenne's  disease ;  hyper- 
geusia ;  ageusia. 
The  pneumogastric  nerve.  ....    482-505 

Its  supeeficial  and  deep  points  of  oeigin. 
Its  intimate  affiliation  with  the  glosso-phaetngeal  neeve. 
Its  ganglionic  enlaegements. 
The  inheeent  fibees  of  its  teunk. 
Its  beanches  of  disteibution  and  theie  functions. 

The  pharyngeal  branches :  effects  on  deglutition ;  effects  on 
voice.  The  laryngeal  branches:  their  relation  to  phona- 
tion ;  their  relation  to  respiration ;  their  relation  to  spinal 
accessory  nerve.  The  branches  to  alimentary  canal:  their 
relation  to  peristaltic  action  ;  their  relation  to  secretion. 
The  cardiac  branches:  depressor  nerve  of  heart's  action; 


XVlll 


TABLE  OF  CONTENTS. 


effects  of  galvanism.     Vaso-raotor  fibers :  effects  on  blood- 
vessels.    The  pulmonary  branches:  their  relation  to  respi- 
ration— acceleratory  fibers;  inhibitory  fibers. 
The  ooubse   and  eelations  of   the  nerve  on  each  side  of 

THE   BODY — 

With  carotid  artery ;  with  jugular  vein  ;  with  oesophagus;  with 
the  lungs;  with  the  abdominal  viscera. 
Effects  of  section  of  the  pneumogastrio  trunk. 

Upon  the  larynx;  upon  the  lungs;  upon  the  heart.    Upon  the 
digestive  tract :  stomach  ;  liver ;  intestinal  canal. 
Clinical  points  pertaining  to  the  nerve. 

Pharyngeal  anaesthesia ;  pharyngeal  spasm;  pharyngeal  paraly- 
sis;  laryngeal  spasm  (Kopp's  asthma);   whooping  cough; 
aneurysmal  cough  ;  pulmonary  asthma ;  pulmonary  vaso-mo- 
tor  paralysis ;  angina  pectoris ;  cardiac  neuralgia ;  gastrodyn- 
ia;  boulimia;  polydipsia;  dyspeptic  vomiting ;  polyphagia. 
The  spinal  accessory  nerve       .... 
Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
Its  filaments  of  communication. 
Its  relations  to  the  production  of  toiOE. 
The  effects  of  section  of  the  nerve. 

On  phonation;  on  respiration;  on  deglutition;  on  the  action 
of  the  heart ;  on  singing. 
Clinical  points  pertaining  to  the  nerve. 

Tonic  spasm  of  sterno-mastoid  muscle ;  tonic  spasm  of  trape- 
zius; clonic  spasm  of  sterno-mastoid  and  trapezius  mus- 
cles ;  salaam  convulsion  of  Newnham ;  unilateral  paralysis 
of  sterno-mastoid  and  trapezius  muscles ;  bilateral  paralysis 
of  sterno-mastoid  and  trapezius  muscles. 
The  hypoglossal  nerve  (sub-lingual  nerve)  . 
Its  superficial  and  deep  points  of  origin. 
Its  course  and  distribution. 
The  desoedens  noni  branch. 

Functions  of  the  nerve:  on  deglutition ;  on  articulation. 
Clinical  points  pertaining  to  the  nerve. 

Duchenne's  disease:  abnormalities  of  speech  ;  abnormalities  of 
voice ;  impairment  of  deglutition ;  facial  deformity ;  lingual 
tremor.    Lingual  spasm :  lingual  paralysis. 


505-518 


618-532 


PART    Til. 


THE  SPINAL  COPvD  ...... 

Its  anatomical  construction,  functions,  and  clinical  bear- 
ings. 
Its  cervical  and  lumbar  enlargements. 
Its  fissures  and  columns. 


533-638 


TABLE  OF  CONTENTS.  xix 


Its  nerves  (theie  eoots  and  general  construction). 
Its  membranes  and  the  cerebro-spinal  fluid. 

Their  functions  and  situation. 
Blood-vessels  of  the  cord. 
vertebrji:  as  guides  to  spinal  segments. 
Histological  elements  of  the  coed. 
Appearance  of  a  transverse  section  of  the  cord. 

Its  gray  matter;  its  white  matter;  its  central  canal;  its 
commissures.  Pathological  subdivisions  of  the  cord :  col- 
umns of  Goll;  columns  of  Burdach;  columns  of  Turck; 
fundamental  columns;  direct  pyramidal  columns;  anterior 
root  zones;  posterior  root  zones;  crossed  pyramidal  col- 
umns; direct  cerebellar  columns. 
Functions  of  the  spinal  cord. 
{!)  Organ  of  conduction. 

Paths  of  motor  impulses ;   paths  of  sensory  impulses ; 
commissural  fibers.    Fibers  of  the  spinal  cord  :  motor 
fibers  and  their   function;    sensory  fibers  and  their 
function  ;  commissural  fibers  and  their  function. 
(2)  Spinal  cord  as  a  nerve  center. 

Reflex  action  of  the  cord  ;  automatic  action  of  the  cord ; 
vaso-motor  centers ;  cilio  spinal  center ;  genito-uri- 
nary  center  ;  tonic  action  on  muscles  ;  center  of  defe- 
cation; center  of  parturition;  center  of  micturition; 
center  of  erection. 
{3)  Organ  of  coordination  of  muscular  movements. 
Clinical  points  pertaining  to  the  spinal  cord. 

The  kinesodic  system  ;  tlie  sesthesodic  system ;  diseases  of  its 
substance. 
Systematic  lesions  of  ^sthesodic  system. 
(i)  Sclerosis  of  columns  of  Goll. 

{2)  Sclerosis  of  columns  of  Burdach  (locomotor  ataxia). 
Systematic  lesions  of  kinesodic  system. 
(i)  Sclerosis  of  columns  of  TurcTc. 

(2)  Sclerosis  of  lateral  columns  (spasmodic  tabes,  tetanoid  pa- 
ralysis, spastic  spinal  paralysis). 
{3)  Amyotrophic  lateral  sclerosis  of  the  cord. 

(4)  Myelitis  of  the  anterior  horns  of  the  gray  matter  (atrophic 

spinal  paralysis). 

(5)  Polio-myelitis. 

Acute  variety ;    infantile  spinal   paralysis ;    non-febrile 
variety ;  chronic  variety. 
{6)  Progressive  muscular  atrophy. 
(7)  Central  myelitis. 
Kon-systematio  or  "focal"  lesions  of  the  cord. 
-     Distinctions  between  systematic  and  focal  lesions;  their  physi- 
ological effects  at  different  heights, 
(i)  Focal  lesions  of  the  upper  cervical  region. 

Symptoms  referable  to  the  phrenic  nerve ;  to  the  respira- 


XX 


TABLE  OF  CONTENTS. 


tory  center;  to  the  acceleratory  center  of  the  heart; 
to  the  pneumogastric  nerve. 

{2)  Focal  lesions  of  the  cervical  enlargement. 

Symptoms  referable  to  cilio-spinal  center;  to  the  ulnar 
nerve ;  to  the  acceleratory  center  of  the  heart ;  to  the 
vaso-motor  centers. 

{3)  Focal  lesions  of  the  mid-dorsal  region. 

Symptoms  referable  to  the  lower  limbs;  to  the  genito- 
urinary organs;  to  the  reflex  excitability  of  the  spinal 
cord;  to  the  lateral  columns  of  the  spinal  cord;  to 
the  rectum. 

(4)  Focal  lesions  above  the  lumbar  enlargement. 

Symptoms  referable  to  reflex  excitability  of  the  spi- 
nal cord ;  to  the  genito-urinary  organs ;  to  the  rec- 
tum. 

(5)  Focal  lesions  of  the  lumbar  enlargement  of  the  spinal  cord. 

Symptoms  referable  to  the  sciatic  nerve;  to  the  rec- 
tum. 

(6)  Focal  lesions  of  one  lateral  half  of  the  spinal  cord. 

(a)  Spinal  hemiplegia — symptoms  referable  to  the  inter- 
costal nerves ;  to  the  upper  extremity ;  to  the  lower 
extremity ;  to  the  cilio-spinal  center ;  to  the  vaso- 
motor centers. 

(5)  Ilemi-paraplegia — symptoms  referable  to  the  trunk; 
to  "trophic"  centers;  to  increased  excitability  of  the 
spinal  cord ;  to  the  lower  limbs. 


I 


PART    lY. 

THE  SPINAL  NERVES  .....     639-772 

Their  sijbdivisioxs  and  points  of  escape. 
The  construction  and  relative  size  of  their  roots. 
The  length  and  inclination  of  their  roots. 
General  axioms  of  nerve  distribution. 
The  upper  cervical  nerves         ....     648-663 
Table  of  their  branches  of  distribution  ;  the  cervical  plexus — 
its  situation,  formation,  superficial  branches,  deep  bnmches, 
and  communications  with  other  nerves.     The  communicans 
noni  nerve:  its  origin  and  distribution.     The  phrenic  nerve: 
its    origin,   course,    surgical    relations,   and    physiological 
function.     Clinical  points  pertaining  to  the  upper  cervical 
nerves:  cervico-occipital  neuralgia;  diaphragmatic  neural- 
gia;   clonic  diaphragmatic   spasm   (hiccough)  ;    tonic  dia- 
phragmatic spasm  (diaphragmatic  tetanus) ;   and  diaphrag- 
matic paralysis. 
The  lower  cervical  nerves        ....     663-705 
Table  of  their  branches  of  distribution.     The  brachial  plexus: 
its  situation;  its  formation  and  abnormalities;  its  supra- 


TABLE  OF  CONTENTS.  xxi 


clavicular  branches ;  its  infra-clavicular  branches;  its  surgi- 
cal relations ;  its  communications  with  other  nerves.  Nerves 
of  the  upper  extremity;  table  of  the  branches  of  the  outer 
cord  of  the  brachial  plexus ;  table  of  the  branches  of  the  in- 
ner cord  of  the  brachial  plexus ;  table  of  the  branches  of  the 
posterior  cord  of  the  brachial  plexus.  The  anterior  thoracic 
nerves:  their  distribution;  their  clinical  aspects.  The  exter- 
nal or  musculo-cutaneous  nerve :  its  course  and  distribution 
to  muscles ;  its  cutaneous  distribution ;  its  relation  to  the 
"  bent  arm  "  after  venesection.  Clinical  points  afforded  by 
it :  paralysis  and  its  symptoms ;  anaesthesia  of  forearm. 
The  median  nerve:  its  origin,  course,  and  distribution;  its 
surgical  relations;  its  cutaneous  distribution.  Clinical 
points  afforded  by  it:  median  paralysis  and  its  symptoms; 
anaesthesia  and  its  variations.  The  internal  and  lesser  in- 
ternal cutaneous  nerves:  their  origin,  course,  and  distribu- 
tion; relations  to  the  intercosto-humeral  nerve.  The  ulnar 
nerve :  its  origin,  course,  and  distribution ;  its  surgical  rela- 
tions ;  its  cutaneous  distribution.  Clinical  points  afforded 
by  it :  ulnar  paralysis,  its  causes  and  symptoms;  its  Relation 
to  the  surgery  of  the  elbow-joint.  The  sub-scapular  nerves : 
their  origin,  course,  and  distribution ;  their  surgical  relations ; 
their  cutaneous  distribution.  Clinical  points  afforded  by 
them  :  scapular  paralysis.  The  circumflex  nerve :  its  origin, 
course,  and  distribution;  its  surgical  relations;  its  cutaneous 
and  articular  branches.  Clinical  points  afforded  by  it :  cir- 
cumflex paralysis;  deltoid  atrophy.  The  mu^culo-spiral 
nerve:  its  origin,  course,  and  distribution.  Its  terminal 
branches  (the  radial  and  interosseous  nerves) :  their  distri- 
bution to  muscles;  their  cutaneous  distribution.  Clinical 
points  afforded  by  it :  surgical  importnnce  of  its  peculiar 
course  ;  its  relation  to  traumatic  paralysis;  rheumatic  affec- 
tions of  the  nerve.  Lead-paralysis :  theories  as  to  its  etiol- 
ogy; its  symptoms;  its  differential  diagnosis;  its  duration. 
The  dorsal  nerves  .....     705-723 

The  thoracic  intercostal  nerves;  the  thoracico-ahdominal  in- 
tercostal nerves:  their  origin,  course,  and  distribution;  their 
relation  to  the  pleura.  Clinical  points  afforded  by  them : 
significance  and  diagnostic  value  of  thoracic  pain ;  signifi- 
cance of  pain  in  the  pit  of  the  stomach;  significance  of  pec- 
toral pain ;  significance  and  course  of  pain  due  to  the  liver 
and  other  viscera.  Intercostal  neuralgia:  its  causes;  its 
symptoms ;  its  differential  diagnosis.  Neuralgia  of  the  mam- 
mary gland  (raastodynia) :  its  causes  and  symptoms;  its 
"puncta  dolorosa."  Paralysis  of  the  dorsal  nerves :  its  re- 
lations to  kyphosis ;  its  relations  to  scoliosis.  Paralysis  of 
the  extensor  mnscles  of  the  lumbar  region:  its  diagnostic 
attitude ;  its  differential  diagnosis. 


xxii  TABLE  OF  CONTENTS. 

PAGES 

The  lumbar  nerves  .  .  .  .  .     722-743 

The  lumbar  plexus:  its  situation  and  formation;  its  chief 
brandies  and  their  general  distribution.  The  ilio-hypo- 
gastric  nerve:  its  origin,  course,  and  distribution;  neuralgia 
of  the  nerve.  The  ilio- inguinal  nerve:  its  origin,  course, 
and  distribution  ;  neuralgia  of  th§  nerve  ;  its  relation  to  the 
peritonaeum.  The  external  cutaneous  nerve :  its  origin,  course, 
and  distribution ;  its  relation  to  pains  referred  to  the  thigh. 
The  genito-crural  nerve:  its  origin,  course,  and  distribution. 
Clinical  points  afforded  by  it.  The  anterior  crural  nerve: 
its  origin,  course,  and  distribution ;  its  physiological  func- 
tions; its  distribution  to  joints:  its  cutaneous  branches. 
Clinical  points  afforded  hj  it :  its  surgical  relations ;  its  rela- 
tion to  pain  in  the  region  of  the  knee.  Spasm  of  the  quad- 
riceps extensor  muscle.  Crural  pai-alysis:  its  causes  and 
Symptoms.  Atrophy  of  muscles  supplied  by  this  nerve. 
Crural  neuralgia:  its  causes;  its"puncta  dolorosa";  the 
"  spasmodic  contracture  of  Stromeyer.*'  The  obturator 
nerve :  its  origin,  course,  and  distribution ;  its  distribution 
to  joints ;  its  relation  to  pain  in  the  vicinity  of  tiie  knee ;  its 
physiological  functions.  Clinical  points  afforded  by  it : 
obturator  neuralgia:  obturator  paralysis.  The  accessory 
obturator  nerve:  its  origin,  course,  and  distribution ;  its  ab- 
normalities. 

The  sacral  nerves  .....     743-772 

Their  anatomical  peculiarities.  The  sacral  plexus:  its  shape 
and  formation ;  its  situation ;  its  branches  of  distribution. 
The  superior  gluteal  nerve:  its  origin,  course,  and  distribu- 
tion ;  its  physiological  function.  Clinical  points  afforded  by 
it:  peculiarities  of  its  cutaneous  distribution;  its  surgical 
relations ;  gluteal  spasm  ;  gluteal  paralysis.  The  muscular 
branches  of  the  sacral  plexus:  their  distribution;  their 
physiological  functions.  The  small  sciatic  nerve :  its  origin, 
course,  and  distribution;  its  physiological  functions;  rela- 
tion of  its  perineal  branch  to  the  genital  organs.  The  pudic 
nerve:  its  origin,  course,  and  distribution;  the  inferior 
hsemorrhoidal  nerve  ;  the  perineal  nerve ;  the  dorsal  nerve 
of  the  penis.  Clinical  points  afforded  by  the  pudic  nerve : 
its  relations  to  coitus ;  its  relations  to  micturition  ;  its  rela- 
tions to  defecation  ;  neuralgic  affection  of  its  branches. 
The  great  sciatic  nerve :  its  origin,  course,  and  distribution  ; 
its  distribution  to  joints.  The  external  popliteal  nerve  :  its 
course  and  branches  of  distribution.  Distribution  of  nerves 
to  the  fascia  of  the  leg.  The  internal  popliteal  nerve  :  ita 
course  and  branches  of  distribution.  Clinical  points  afforded 
by  the  great  sciatic  nerve  and  its  branches.  Sciatic  neuralgia 
(malum  Cotunnii) ;  its  causes;  modifications  of  its  seat ;  its 
characteristic  symptoms ;  its  "  puncta  dolorosa" ;  its  motor 


TABLE  OF  CONTENTS.  xxiii 


manifestations;  its  vaso-motor  effects.  Spasms  of  the  lower 
limb :  spasmodic  contraction  of  the  hip  ;  tonic  and  clonic 
spasms  of  extensor  and  adductor  groups  of  muscles  ;  spasm 
of  the  anterior  muscles  of  the  leg.  Paralysis  of  the  great 
sciatic  nerve  or  its  branches :  sciatic  paralysis ;  peroneal 
paralysis;  tibial  paralysis;  their  sensory  manifestations ; 
their  trophic  disturbances. 
INDEX  ........     772-791 


I 


LIST    OF    ILLUSTEATIONS. 


1.  Nerye  fibers  from  the  human  subject    . 

2.  Cervical  and   thoracic   portion  of   the 

sympathetic  ..... 

3.  Lumbar  and  sacral  portions  of  the  sym- 

pathetic    ..... 

4.  Fibers  of  Remak       .... 

5.  Mode    of    termination    of     the     motor 

nerves         ..... 

6.  Plan   in   outline   of   the   brain  in   pro- 

file ..... 

7.  A  diagram  of  the  chief  component  parts 

OF   THE   HUMAN   BRAIN 

8.  A   DIAGRAM    OF   THE   GENERAL    ARRANGEMENT 

OF    THE    FIBERS    OF     THE     CEREBRO-SPINAL 
SYSTEM  ..... 

9.  Diagram  of   the  commissural   fibers   of 

THE   anterior   REGION    OF    THE   BRAIN 

10.  Diagram   of  the   commissural   fibers   on 

the  level  of  the  corpus  striatum 

11.  Diagram  to  illustrate  the  general  out- 

line   OF  THE    CORPUS    CALLOSUM    AND   THE 
FORNIX  ..... 

12.  Schematic  representation   of   Meynert's 

THREE      projection      SYSTEMS      OF     NERVE 
FIBERS  ..... 

13.  Diagrammatic     representation     of     the 

fibers  in  the  cerebrum  . 

14.  Diagram  of  the  course  of  sensory  and 

motor  tracts  in  the  mesocephalon  and 
hemispheres  .... 

15.  a  diagram  of  the  brain  in  transverse 

vertical  section  .... 

16.  Structure  of  the  convolutions     . 


Kollilcer  . 

PAGE 

5 

Sappey 

6 

Rolin  . 

8 
11 

Rouget . 

12 

Quain  . 

23 

Ranney 

24 

Ranney 
(modified  from 

Landois)     25 

Lvys     . 

27 

(( 

29 

Allen  (modified  from)  80 


Ranney 
Le  Bon 

Seguin  . 

Dalton 
Baillarger 


82 
36 

38 

89 
44 


XXVI 


LIST  OF  ILLUSTRATION'S. 


17.  Cortical  cell  of  the  deeper  zones  .     Luys     . 

18.  Half  diagrammatic  figcre  of  the  cere- 

bral   cortex,   giving    a    view   of    the 

arrangement  of  the  different  Z0NE8 
OF  CELLS,  AND  TIIEIR  RELATIONS  TO  ONE 
ANOTHER,  AND  TO  THE  SURROUNDING  NEU- 
ROGLIA .  .  .  .  .  "  . 

19.  A   TRANSPARENT   SECTION   FROM   A    SULCUS  OF 

THE   THIRD   FRONTAL   CONVOLUTION   OF  THE 

HUMAN  BRAIN         ....     Meyuevt 

20.  Lateral  view  of  the  human  beain,  show- 

ing ITS  lobes  AND  FISSURES  .  .     FevHer 

21.  A    diagram     of    THE     CEREBRUM     IN     LONGI- 

TUDINAL  MEDIAN    SECTION  .  .  .      DaltOTl  . 

22.  A    diagrammatic    figure,    showing    the 

cerebral  convolutions    .  .  .         "      . 

23.  Orbital  surface  of  the  frontal  lobe  and 

island  of  Reil     ....     Turner 

24.  A   diagram  of  the  fibers  of  a  lateral 

half  of  the  cerebrum     .  .  .     Reichart 

25.  Side    view   of    the    brain    of    man    and 

the  areas  of  the  cerebral  convolu- 
tions .....     Ferrier 

26.  Upper  view   of   the   brain  of  man   and 

THE  situation  OF  AREAS  OF  THE  CERE- 
BRAL convolutions  .  .  .  '* 

27.  A   diagram   illustrating   the   course   of 

NEKVE   impulses   IN   THE   CEREBRUM  .      Dodds    . 

28.  Superior  aspect  of  the  encephalon         .     Hirschfeld 

29.  Convolutions  on  the  internal  aspect  of 

the   CEREBRAL   HEMISPHERES  .  .      Sappey 

30.  Outline   of   skull  resting  upon  the  al- 

VEOLO- CONDYLOID   PLANE   OF   BeOOA  .       SegUlTl  . 

31.  AnTERO-POSTERIOR  vertical  SECTION  OF   THE 

RIGHT   HEMISPHERE.  .  .  .      DaltOU  . 

32.  A  diagram  of  the  afferent  and  efferent 

FIBERS  OF  THE  CORPUS  STRIATUM  .  .     Ranuey 

33.  View  from   above  of  the  third  ventri- 

cle AND  A  PART  OF  THE  LATERAL  VEN- 
TRICLES        .....     Henle    . 

34.  Section   across  the  optic  thalamus  and 

CORPUS  striatum  in  the  region  of  the 

MIDDLE    COMMISSURE  .  .  .      Sckofer 

35.  Right  half  of  the  encephalic  peduncle 

AND  cerebellum,  AS  SEEN  FROM  THE  IN- 
SIDE  OF   A    MEDIAN   SECTION  .  .      Reichavt 

36.  A    DIAGRAM    OF    THE    NUCLEI    OF    THE    OPTIC 

THALAMUS  AND  THE  CONVERGING  FIBERS 
ASSOCIATING   WITH   THEM      .  .  .      LuyS      . 


PAGE 

46 


LIST  OF  ILLUSTRATION'S. 


XX  vu 


FIO. 

37.  a  diagram  of  the  inner  surface  of  the 

optic  thalamus,  with  the  tubular  gray 
matter  removed  ;  showing  the  third 
ventricle,  and  the  arrangement  of 
neighboring  parts 

38.  a  diagram  of  the  relations  of  the  in- 

ternal capsule  of  the  cerebrum  to  ad- 
jacent structures  viewed  from  above  . 

39.  a    diagram  of   the   subdivisions  of    the 

internal  capsule  .... 

40.  a  diagram  of  the  afferent  and   effer- 

ent fibers  of  the  corpus  striatum 

41.  Miliary  aneurysms  .... 

42.  a  diagram  of  the  relations  of  the  optic 

and  olfactory  nerve  fibers  to  sur- 
rounding parts    .... 

43.  a  diagram  to  illustrate  the  latest  views 

in  reference  to  the  course  of  the  op- 
tic fibers  ..... 

44.  a    diagram    of    the    general  course  of 

fibers  in  the  "  sensory  "  and  "motor 
tracts,"  and  their  relation  to  cer- 
tain fasciculi  of  the  optic  tracts 

45.  a   diagrammatic  representation   of   the 

parts  seen  in  a  horizontal  cross-sec- 
tion on  a  level  with  the  superior 
quadrigeminal  body 

46.  a  diagram  of  the  course  of  the  fibers  of 

THE  CRUSTA  CEREBRI  (MOTOR)  AFTER  THEY 

leave  the  pyramids  of  the  medulla   . 

47.  Cerebellum  and  medulla  oblongata 

48.  a  diagram  of  the  various  sets  of  fibers 

comprised   within    the    cerebro-spinal 

SYSTEM  ..... 

49.  k  crude  diagram  illustrating  the  three 

pairs  of  peduncles  of  the  cerebellum 

50.  Anterior  view  of  the  medulla  oblongata 

51.  Anterior  view  of  the  medulla  and  pons, 

designed  to  show  some  of  the  rela- 
tions of  surrounding  parts  and  the 
apparent  origin  of  the  cranial  nerves 

52.  a  diagram  to  show  the  more  important 

subdivisions  of  the  spinal  cord 

53.  a  diagram  of  a  section  of  the  medulla 

at  the  middle  of  the  motor  decussa- 
TION ..... 

54.  A    DIAGRAM    OF    A    SECTION    OF    THE    MEDULLA 

AT  A  SLIGHTLY  HIGHER  LEVEL  THAN  IN 
THE   PRECEDING   FIGURE 


Ranney 


Hammond 


Ranney 


Eanney 

(modified  from  Seguin) 


Eanney 


149 

152 

154 

160 
164 

185 

189 

193 

201 


44 

nirschfeld 

203 

217 

Ranney 

(modified  from  Ross)   . 

224 

Ranney 
Sappey 

227 
245 

Ranney 
Fleehaig 


248 
250 


Ranney  (after  Quain)       251 


252 


xxvni 


LIST  OF  ILLUSTRATIONS. 


FIO. 

55. 


56. 
57. 

58. 

59. 

60. 
61. 

62. 

63. 

64. 

65. 
66. 
67. 


68. 
69. 

70, 

72. 


Teaxsparent  lateral  view  of  the  medui^ 
la,  showing  the  relative  positions  op 
most  important  nuclei ;  right  half  of 
the  medulla,  seen  from  the  surface  of 

section;    the    parts   that   lie    closer   TO 

this  surface  are  deeper  shaded 

Diagram  of  the  chief  tracts  in  the  me- 
dulla ..... 

A  cross-section  of  the  medulla  oblon- 
gata ON  A  level  with  THE  SUPERFICIAL 
ORIGIN    OF   THE   AUDITORY   NERVE    . 

A  TRANSVERSE  SECTION  THROUGH  THE  PONS, 
ON  A  LEVEL  WITH  THE  ROOTS  OF  THE 
SIXTH  AND  SEVENTH  CRANIAL  NERVES 
FROM   A   NINE   MONTHS'    EMBRYO 

A  TRANSVERSE  SECTION  OF  THE  MEDULLA 
(partly  schematic)  MADE  THROUGH  THE 
MIDDLE   OF   THE   OLIVARY   BODY 

The  PATHS  OF  the  motor  fibers  of  the 

CORD  ..... 

a  diagram  of  the  two  subdivisions,  or 
tracts,  of  the  anterior  root  zones  of 
the  spinal  cord    .... 

a  diagram  of  the  right  lateral  half 
of  a  transverse  section  of  the  pons 
Varolii  on  a  level  with  the  origin 
of  the  fifth  cranial  nerve 

a  diagram  of  the  course  of  certain 
special  nerve  tracts  within  the  cere- 
brum, orus  cerebri,  pons  varolii,  me- 
dulla oblongata,  and  spinal  cord 

a  diagram  of  the  relative  situation  and 
functional  association  of  the  direct 
cerebellar  column  of  the  spinal  cord, 

AND   THE   VESICULAR   COLUMN   OF   ClARKE 

a  diagram  to  illustrate  the  method  of 
production  of  crossed  paralysis 

View  from  above  of  the  third  ventricle 
and  a  part  of  the  lateral  ventricles 

a  diagram  of  the  inner  surface  of  the 
OPTIC  thalamus,  with  the  tubular  gray 
matter  removed,  showing  the  third 
ventricle,  and  the  arrangement  of 
neighboring  parts 

The  base  of  the  skull  and  cranial  nerves 

a  diagram  of  the  probable  decussation 
of  the  fibers  of  the  olfactory  tracts 

71.  The  visual  tracts 

The  normal  visual  field 


Erl 


FlecTisig 


254 
255 

258 


Ranney  (modified  from 

Erh  and  Ross)  .       260 

Ranney 

(modified  from  SpitzJca)    262 
Ranney  (modified  from 
Bramwell)        .  .273 


Ranney  .  .274 


(modified  from  Erh)    .      276 


Ranney  (modified  from 
Flechsig)  .  .      280 


.      281 

Hammond        .  .      292 

Eenle  .  .  .309 


Ranney  .  .      812 

'*  .  .       330 

"  .  .       332 

Munh  .  .  .333 

Ro88     .  .  .335 


LIST  OF  ILLUSTRATIONS. 


XXIX 


73.  Horizontal  section  of  a  monkey's  brain 

74.  a  diagram  of  the  origin  and  course  of 

thr  fourth  cranial  nerve 

75.  Section  of  the  medulla  at  its  upper  part 

76.  Roots  of  the  cranial  nerves 

77.  Olfactory  ganglion  and  nerves 

78.  Terminal    filaments   of  the    olfactory 

nerve        ..... 

79.  Internal    branches    of    the    olfactory 

nerve        ..... 

80.  Optic  tracts,  commissure,  and  nerves    . 

81.  A  diagram  of  the  decussation  of  the 

OPTIC   fibers  .  .  . 

82.  A  diagram  of  the  optic  fibers  in   the 

RETINA  ..... 

83.  Relation  of  the  optic  nerve  and  oph- 

thalmic artery    .... 

84.  Relation   of    the   optic  nerve    to    the 

blood-vessels,  in  the  orbit 

85.  A  diagram  of  the  defective  diameters 

of  the  eye  .... 

86.  Anterior  view  of  the  crystalline  lens 

87.  Two   cuts   of  the    retina   and  its  ele- 

ments ..... 

88.  a  diagram  to  show  the  limits  of  color 

VISION  ..... 

89.  Lachrymal  and  Meibomian  glands 

90.  Lachrymal  apparatus 

91.  a  diagram  to  show  the  effects  of  press- 

ure on  the  optic  nerve 

92.  Distribution  of  the  third  cranial  nerve 

93.  The  ciliary  muscle,  lens,  iris,  and  cornea 

94.  The  ciliary  nerves  and  choroid  coat  of 

eye  ..... 

95.  The  nerves  of  the  iris 

96.  The  ciliary  nerves 

97.  a  diagram   showing  the  mechanism  of 

the  accommodation  of  vision  . 

98.  Muscles  of  the  eyeball    . 

99.  a  diagram  showing  the  axes  of  rota- 

TION  of   THE   EYEBALL 

100.  Two    DIAGRAMS    OF    THE    ELEMENTS    OF    THE 

RETINA         ..... 

101.  Distribution     of     the     fourth    cranial 

NERVE  ..... 

102.  The   ophthalmic   division   of   the    fifth 

cranial  nerve     .... 

103.  a  diagram  of   the  distribution  of  the 

fifth   cranial   NERVE 


Werniclce 

Ranney 
Quain  . 
Hirschfeld 


KolUher 

Sappey 
Hirsclifeld 

Flint  . 

Weher  . 

Ranney 


BabucJiin 

Muller  and  Sappey 


PAGE 

337 


HirscKberg 
Sappey 


Ranney 

Hirschfeld 

Sappey 


Fich     . 
Sappey 


Fich     . 

Mailer  and  Sappey 

Hirschfeld 

a 

Floicer  (modified  from) 


XXX 


LIST  OF  ILLUSTRATIONS. 


FIO. 

104.  The  inferior  maxillary  division  of  the 

FIFTH    CRANIAL    NERVE         .  .  .      Hirschfeld 

105.  The  superior  maxillary  division  of  the 

FIFTH   cranial   NERVE         .  .  .  " 

106.  Superficial  branches  of  the  fifth  and 

facial  nerves      .  .  .  .  " 

107.  Cutaneous    nerve    distribution    of   the 

head  .....     Flower 

108.  Distribution  of  the  sixth  cranial  nerve     Hirschfeld 

109.  The  superficial  branches  of  the  facial 

NERVE  ....." 

110.  A     diagram     of     THE     BRANCHES     OF     THE 

FACIAL  NERVE        ....     Ranncy 

111.  Expression  of  the  face  in  "Bell's  pa- 

ralysis" .....     Corfe   . 

112.  A    diagram    of    the    communications    BE- 

TWEEN    the     facial    and     trigeminus 

NERVES      .....     Ranney 

113.  The  chorda  tympani  nerve  .  .     Hirschfeld 

114.  A  diagram  of  the  course  of  the  vidian 

AND  PETROSAL  NERVES         .  .  .      Railliey 

115.  A   diagram    of   THE    AUDITORY    NERVE     AND 

ITS   BRANCHES  .  .  .  .  " 

116.  Distribution  of  the  cochleae  nerve      .     Sappey 

117.  General  view  of  the  organ  of  hearing  " 

118.  A   DIAGRAM   to  ILLUSTRATE    THE   MECHANISM 

OF  HEARING  ....  Raniiey 

119.  The  ossicles  of  the  tympanum     .  .  Arnold 

120.  The  bony  labyrinth  of  a  new-born  child  Rudringer 

121.  A  diagram  of  the  labyrinth,  vestibule, 

AND  semicircular  CANALS  .  .  " 

122.  A  DIAGRAM  OF  THE  COCHLEA  ON  TRANSVERSE 

SECTION     .....     Ranney 

123.  A    VERTICAL    SECTION    OF    THE     "  ORGAN    OF 

CoRTi"      .....     Waldeyer 

124.  The    two    fillars    of    the    "  organ    of 

CoRTi"      .....  Sappey 

125.  Distribution  of  the  cochlear  nerves     .         " 

126.  Membrana  tympani,  seen  from  within    .  Rudringer 

127.  Section  of  the  cochlea  of  the  cat  and 

human  fcetus       .  .  .  .  " 

128.  The  glosso-pharyngeal  nerve      .  .     Sappey 

129.  A    diagram   of    the    glosso-pharyngeal 

NERVE        .....  Ranney 

130.  The  papilla  of  the  tongue         .  .  Sappey 

131.  A  oircumvallate  papilla  .  .  .         " 

132.  The  fungiform  and  filiform  papillae     .         " 

133.  The  taste-buds        ....  Engelmann 

134.  The  cavities  of  the  mouth  and  pharynx  Sappey 


LIST  OF  ILLUSTRATIONS. 


XXXI 


Hirschfeld 
Sappey 

44 

.  487 
.  488 
.  490 
.      490 

Bernard 
Hirschfeld 

.  491 
.       506 

Sappey 

.      507 

44 

.      507 

Ranney 

.      508 

Le  Bon 
Sappey 

44 

.  509 
.  511 
.      519 

135.  The  muscles  of  the  pharynx       .  .     Sappey 

136.  Anastomoses  of  the  pneumogasteio  nerve    Hirschfeld 

137.  a  diagram  of  the  cervical  portion  of 

the  pneumogasteic  nerve 

138.  a  diagram  of  the  thoracic  and  abdomi- 

nal portions    of   the  pneumogastric 

NERVE  ..... 

139.  Distribution  of  the  pneumogastric  nerve 

140.  Nerves  of  the  larynx,  posterior  view  . 

141.  Nerves  of  the  larynx,  lateral  view  . 

142.  Branches  of  the  pneumogastric  nerve 

to  the  heart   .... 

143.  The  spinal  accessory  nerve 

144.  Posterior  view   of  the  muscles  of  the 

larynx      ..... 

145.  Lateral  view   of   the  muscles    of    the 

LARYNX        ..... 

146.  A      DIAGRAM     OF     THE      SPINAL     ACCESSORY 

NERVE  ..... 

147.  The  glottis,  as  seen  with  the  laryngo- 

scope DURING  the  emission  OF  HIGH- 
pitched  sounds   .... 

148.  The  spinal  accessory  nerve 

149.  Distribution  of  the  hypoglossal  nerve 

150.  Anastomotic    loop    formed   by  the   de- 

scending branch  of  the  hypoglossal 
nerve  and  the  internal  descending 
branch  of  the  cervical  plexus 

151.  a  diagram  of   the  hypoglossal    nerve 

and  its  branches 

152.  Glosso-labio-laryngeal  paralysis 

153.  Glosso-labio-laryngeal  paralysis 

154.  A   DIAGRAM   of   THE    MOTOR   POINTS    OF   THE 

face,  showing  the  position  of  the 
electrodes  during  electrization  of 
special  muscles  and  nerves 

155.  Cervical  portion  of  the  spinal  cord     . 

156.  Dorsal  portion  of  the  spinal  cord         .  " 

157.  Inferior    portion    of    the    spinal   cord 

and  cauda  equina  ..." 

158.  Transverse  section  of  the  cervical  en- 

largement OF  THE  spinal  CORD   AT  THE 

ORIGIN    OF    THE    FIFTH    PAIR    OF    NERVES     .       Stilling 

159.  Transverse  section  of  the  spinal  cord 

OF  A  child  six  MONTHS  OLD       .  .     Gcrlach 

160.  Diagram   of    the    arrangement   of    the 

different  membranes  and  spaces  as 
they  are  believed  to  exist  in  the 
SPINAL  column     ....     Hilton 


PAGK 

476 

483 

484 


Hirschfeld 

Ranney 
Hammond 


Ziemssen  (modified 
from)    . 
Hirschfeld 


520 

521 
524 

525 


528 
534 
534 

534 


536 
538 

540 


XXXll 


LIST  OF  ILLUSTRATIONS. 


FIG. 

161.  A   DIAGEAM    DESIGNED    TO    SHOW    THE    RELA- 

TIONS OF  THE  VERTEBK^  TO  THE  SPINAL 
SEGMENTS,  AND  OF  THE  SPINAL  NERVES  TO 
THE  MOTOR,  SENSORY,  AND  REFLEX  FUNC- 
TIONS  OF    THE    SPINAL   CORD  .  .       Gowei'S 

162.  SeMI-DIAGRAMMATIC  TRANSVERSE  SECTION  OF 

THE  GRAY  SUBSTANCE  OF  THE  CERVICAL 
AND  LUMBAR  ENLARGEMENTS  OF  THE  SPI- 
NAL CORD  .....     Erb 

163.  A    PIECE    OF    THE   WHITE    SUBSTANCE    OF   THE 

SPINAL  COED,  AS   SEEN  ON  A   TRANSVERSE 

SECTION        .  .  .  .  .  "  . 

164.  Section  of  the  cord  below  the  medulla 

OBLONGATA       ....  Sappcy 

165.  Section  of  the  cervical  enlargement 

of  the  coed    .     .     .     .    " 

166.  Section  from  the  dorsal  region  of  the 

CORD  ....." 

167.  Section  of  the  lumbar  enlargement  of 

the  cord  ....." 

168.  Diagram  illustrating  the  relations  of 

the  nerve-fiber  tracts  in  the  spinal 
cord  ..... 

169.  A  diagram  of  the  areas  of  the  direct 

and  crossed   pyramidal  tracts    in  a 

SECTION    OF    the    SPINAL   CORD,    AND    THE 

FIBERS   THAT   COMPOSE    EACH  .  .       RaUUey 

170.  A  DIAGRAM  ILLUSTRATING  THE  DEVELOPMENT 

OF  THE    DIFFERENT   SYSTEMS    OF  FIBERS    IN 

THE   SPINAL   COED  ....       Flcchdg 

171.  Diagram   of    a   transverse    section    of 

spinal  cord  in  upper  half  of  dorsal 

REGION  ....." 

172.  Diagram  of  a  spinal  segment  to  show 

ITS  component  parts      .  .  .     Ranney 

173.  A     DIAGEAM     to      ILLUSTRATE     THE      CIRCLE 

OF  REFLEX  ACTION  IN  A  SPINAL  SEG- 
MENT ..... 

174.  A    DIAGRAM    OF    THE    PATHS    OF    MOTOE    AND 

8ENS0EY  CONDUCTION  IN  THE  SPINAL 
COED  ..... 

175.  A    DIAGEAM    OF    THE    CONNECTIONS    OF    THE 

MOTOE  AND  SENSORY  CONDUCTING  TRACTS 
WITH   THE    SPINAL  NERVES 

176.  A    DIAGRAM  OF  THE  VARIOUS    PATHS    OF  SEN- 

SORY CONDUCTION  IN  THE  CORD  .  .     RauTiey 

177.  Multipolar  nerve  cell  from  the  ante- 

eioe    coenu    of    the    spinal  cord   of 

THE  OX      .  .  .  .  .     Deiters 


,      546 

.   553 

.   554 
555 

.   555 
.   556 


"        .     .   556 

Ranney  (modified  from 
Flechsig)  .  .   Plate 


559 

564 

565 
567 


Ranney  (modified  from 
Bramwell)        .  .       567 

Ranney  (modified  from 
Bramwell)        .  .      509 

Ranney  (modified  from 
Bramwell)        .  .      571 


.      572 


581 


I 


LIST  OF  ILLUSTRATIONS, 


XXXlll 


FIG. 

178.  Teansveese    section    of    the    geay   sub- 

stance   OF    THE     ANTEEIOE     COENUA     OF 

the  spinal  coed  of  the  ox,  teeated 
with  niteate  of  silver  . 

179.  a  diageam  of  the  couese  of  the  fibees 

which  compose  the  spinal  coed 

180.  Nerve   cell  feom  the  feeeuginous  sub- 

stance WHICH   FOEMS  THE   FLOOE   OF  THE 
EHOMBOIDAL   SINUS   IN   MAN 

181.  A    DIAGEAM    TO    SHOW    THE    DECUSSATION    OF 

MOTOE     NEEVE    FIBEES    IN    THE     MEDULLA 
OBLONGATA  .... 

182.  AtEOPHIC     SPINAL     PAEALYSIS      WITH      CON- 

teactuee  ..... 

183.  Peogeessive  muscular  ateophy  of  the 

UPPEE   EXTEEMITY  .... 

184.  Peogeessive  musculae  ateophy.     Age  of 

patient,  foety-five  yeaes 

185.  a  diageam  showing  the  eelation  of  the 

spinous  peooesses  of  the  veetebe^  to 
the  spinal  neeves  and  spinal  coed    . 

186.  a  diageam  to  show  the  couese  of  the 

motoe  and  sensoey  paths  in  the  spi- 
NAL   COED  ..... 

187.  a  diageam  to  show  the  eelation  of  the 

spinous  peocesses  of  the  veetebeie  to 
spinal  neeves      .... 

188.  The  cervical  portion  of  the  spinal  coed 

189.  The  doesal  poetion  of  the  spinal  coed 

190.  The  infeeioe  poetion  of  the  spinal  coed 

and  cauda  equina 

191.  posteeioe  beanch  of  the  second  ceevi- 

oal  neeve 

192.  supeeficial  beanches    of    the  ceevical 

PLEXUS  ..... 

193.  The  neeve  supply  of  the  posteeioe  paet 

OF  THE  head     .... 

194.  The  neeve  supply  of  the  posteeioe  poe- 

tion OF  THE  HEAD  AND  NECK 

195.  A    DIAGEAM    OF    THE   BEACHIAL    PLEXUS    AND 

ITS    BEANCHES  .... 

196.  AnTEEIOE     BEANCHES     OF     THE     FOUE    LAST 

CEEVICAL    AND   FIEST    DOESAL   NEEVES 

197.  COLLATEEAL    BEANCHES     OF     THE     BEACHIAL 

PLEXUS         ..... 

198.  BbACHIAL   PORTION    OF    TOE    MU8CUL0-CUTA- 

neous,  median,  and  ulnae  neeves 

199.  Cutaneous  neeves  of  the  anterioe  sue- 

FACE   OF    the   FOEEAEM   AND   HAND 
3 


Grandry 
Ranney 

Kolliher 

Flechsig  and  Seguin 
Hammond 

Friedreich 


Brown- Sequa/rd 


Malgaigne  and  Seguin 
Eirschfeld 


Arnold 
Hirschfeld 
Hilton  . 
Flower 
Gray  . 
Hirschfeld 


Hirschfeld 


583 
585 

586 

618 
619 
621 
622 


Malgaigne  and  Seguin       626 


635 

636 
642 
642 

642 

649 

651 

652 

653 

665 

666 

667 

672 

675 


XXXIV 


LIST  OF  ILLUSTRATIONS. 


FIG. 

200.  Cutaneous  neeves  of  the  shouldee  and 

POSTEEIOE   surface   OF  THE   ARM. 

201.  Cutaneous  nerves  of  the  posterior  sur- 

face  OF  THE  forearm   AND  HAND 

202.  BeAOHIAL   PORTION   OF    THE    MUSCULO-OUTA- 

neous,  median,  and  ulnar  neeves 

203.  Terminal  poriion  of  the  median  and 

ulnae  neeves   .... 

204.  Diagram  of  the  regions  of  the  cutane- 

ous NERVE  distribution  ON  THE  ANTE- 
rior surface  of  the  uppee  extremity 
and  teunk    .... 

205.  The  cutaneous  nerves  of  the  shoulder 

and  anterior  surface  of  the  arm 

206.  The  cutaneous  neeves  of  the  anterior 

surface  of  the  forearm  and  hand  . 

207.  Brachial  portion  of  the  musculo-cuta- 

neous,  median,  and  ulnar  nerves 

208.  Terminal  portion  of  the  median  and 

ulnae  nerves   .... 

209.  The  circumflex  and  subscapular  nerves 

210.  The  musculo-spiral  nerve 

211.  The  tebminal  branches  of  the  musoulo- 

spieal  nerve   .... 

212.  A  diagram  of  the  regions  of  cutaneous 

NERVE  distribution  ON  THE  POSTERIOR 
SURFACE  OF  THE  UPPER  EXTREMITY  AND 
TRUNK  ..... 

213.  The  motor  points  on  the  outer  aspect 

of  the  arm  .... 

214.  The  motor  points  on  the  inner  side  of 

THE   ARM     ..... 

215.  The  motor  points  on  the  extensor  (pos- 

terior)  ASPECT  OF  THE  FOREARM 

216.  The  motor  points  on  the  flexor  (ante- 

rior)  ASPECT  of  the  FOEEABM    . 

217.  The  intercostal  neeves     . 

218.  The  nerves   situated  on  the  posteriob 

part  of  the  trunk 

219.  a  diagram  of  the  regions  of  cutaneous 

nerve  distribution  in  the  anterior 
surface  of  the  upper  extremity  and 

TEUNK  ..... 

220.  A    DIAGRAM   OF  THE   REGIONS   OF  CUTANEOUS 

NERVE  DISTRIBUTION  ON  THE  POSTERIOR 
SURFACE  OF  THE  UPPER  EXTREMITY  AND 
TRUNK  .  . 

221.  The  lumbar  plexus 

222.  The  ou-daneous  nerves  on  the  thigh 


Sappey 


Flower 
Hirschfeld 


677 
678 
Gsd 
680 

682 

685 

685 

687 

687 
698 
695 

695 


Flower  (modified  from)     697 
Ziemssen       ''  "  701 

702 
703 


it  (.1  u 


((  a 


((  (( 


Masse ' . 


704 

707 

709 


Flower  (modified  from)     71 1 


'15 


HirHchfeld 


LIST  OF  ILLUSTRATIONS. 


XXXV 


FIG. 

223.  The  musoulae  branches  of  the  anterior 

and  internal  portions  of  the  thigh  . 

224.  a  diagram  of  the  cutaneous  supply 

of  the  anterior  aspect  of  the  lower 
extremity      .... 

225.  Cutaneous  nerves  of  the  anterior  part 

of  the  thigh   .... 

226.  Diagram  of    the    cutaneous   supply   of 

the    posterior   aspect   of   the    lower 
extremities  .... 

227.  Muscular  branches  of  the  anterior  and 

internal  portions  of  the  thigh 

228.  The  small  sciatic  nerve  with  its  branch- 

es OF  distribution  and  termination    . 

229.  The  great  sciatic  nerve  with  its  branch- 

es of  distribution  and  termination 

230.  The  external  popliteal  nerve     . 

231.  The  internal  popliteal  nerve     . 

232.  The  external  saphenous  nerve  and  its 

accessory,  the  communicans  peronei  . 

233.  The  plantar  nerves,  their  course,  anas- 

tomoses, and  distribution 

234.  The  deep  branch  of  the  external  plan- 

tar NERVE  .... 

235.  The  motor  points  on  the  posterior  as- 

pect OF  THE  THIGH 

236.  The  motor  points  on  the  anterior  as- 

pect OF  the  thigh 

237.  The  motor  points  on  the  inner  aspect 

OF   the   leg  .... 

238.  The  motor  points  on  the  outer  aspect 

of  the  leg  .  .  . 


PAGB 

Sappey 

731 

Flower  (modified  from) 

732 

Sappey 

735 

Flower  (modified  from) 

737 

Sappey 

739 

u 

751 

a 

756 

a 

757 

11 

759 

IC 

761 

a 

762 

t( 

763 

Ziemssen  (mod.  from) 

766 

1.1                 a           ii 

768 

U                           ((                 (( 

770 

u                u           u 

772 

GEI^ERAL  INTRODUCTION^. 

THE  NERVOUS  SYSTEM  CONSIDERED  AS  A  WHOLE,  AND 
THE  AXIOMS  OF  NERVE  DISTRIBUTION 


GENEEAL    INTEODUCTIOK 


Gentlemen  :  The  subject  of  the  nervous  system,  which 
has  been  chosen  as  the  theme  of  my  winter's  course  of  lect- 
ures, is  one  which  probably  comprises  more  points  of  prac- 
tical interest  than  any  other  portion  of  anatomy.  I  say  of 
practical  interest,  because  there  is  hardly  a  field  of  medicine 
or  of  surgery  where  the  nervous  system  does  not  help  to 
explain  many  of  the  symptoms  which  might  otherwise  tend 
to  possibly  mislead  the  practitioner,  and  where  it  does  not 
also  afford  invaluable  aid  in  the  diagnosis  of  obscure  affec- 
tions which  might  remain  unrecognized,  without  a  knowledge 
of  the  nerves  and  of  their  distribution  and  function,  till  the 
opportunity  of  relief  to  the  patient  has  passed. 

The  distribution  of  those  small  nerve-filaments  which  sup- 
ply the  skin  of  the  body  with  sensation,  and  thus  allow  of  the 
perception  of  external  impressions,  such  as  those  of  heat,  cold, 
pain,  and  touch,  possesses  to-day  an  importance  which  is  not 
confined  to  the  researches  of  the  physiologist,  but  which  the 
advanced  physician  and  surgeon  are  both  keenly  alive  to 
grasp  in  all  its  practical  detail. 

In  every  work  now  published  upon  diseases  of  the  nervous 
system,  you  will  find  cuts,  which,  in  less  modern  treatises, 
have  no  analogue.  These  are  designed  to  show  the  situation 
of  certain  motor  points  on  the  cutaneous  surface  of  the  dif- 
ferent anatomical  regions  of  the  body,  where  the  electric 
current  can  be  best  applied  to  accomplish  certain  desired 
effects,  and  also  the  area  of  cutaneous  distribution  of  each  of 
the  sensory  nerves. 


4  GENERAL  INTRODUCTION. 

The  important  relationship  which  exists  between  the 
nerves  of  the  skin,  the  muscles  underneath  it,  and  the  joints 
which  those  muscles  move,  is  affording  the  enlightened  physi- 
cian a  means  of  tracing  the  seat  of  obscure  affections,  by  the 
use  of  certain  general  rules  governing  the  nerve-supply  of 
tie  body,  with  a  degree  of  accuracy  and  ease  which  strikes 
those  not  familiar  with  the  method  as  remarkable. 

The  investigations  of  Meynert,'  Turck,'  Charcot,"  Ferrier,* 
Brown-Sequard,'  Clarke,"  Flechsig,'  Luys,'  Broca,"  Bouillaud,'" 
Andral,"  and  a  host  of  others,  have  awakened  the  profession 
to  the  fact  that  many  of  the  old  ideas  of  the  anatomy  and 
physiology  of  the  brain  and  the  spinal  cord  were  radically 
wrong.  By  symptoms  referable  to  certain  anatomical  regions, 
the  existence  of  disease  in  certain  corresponding  parts  of  the 
brain  or  spinal  cord  may  now  be  positively  localized  during 
life.  To  what  extent  this  new  guide  to  diagnosis,  given  us 
by  means  of  investigations  calculated  to  determine  the  pre- 
cise distribution  of  the  nervous  system,  may  be  developed  in 
the  future,  time  alone  will  show.  We  have,  however,  ample 
proof  that  some  positive  information  of  a  practical  character 
has  been  gained,  and  that  a  great  advance  has  been  made 
toward  accurate  knowledge  of  the  anatomy  of  the  nervous 
centers. 

When  we  consider  that  every  act  which  distinguishes  the 
animated  being  from  the  corpse  is  dependent  upon  the  influ- 
ence of  the  nerves,  and  that,  without  these  electric  wires,  the 
heart  would  cease  to  throb,  the  lungs  no  longer  perform  their 

*  "  The  Brain  of  Mammals,"  "  Strieker's  Histology,"  New  York,  1872. 
'  A  paper  originally  read  before  the  Academy  of  Vienna  in  1851. 

*  "  Localizations  dans  les  maladies  c6rebrales." 

*  "  Functions  of  the  Brain  "  ;  *'  Localization  of  Cerebral  Disease." 

•>  "  Lectures  on  the  Physiological  Pathology  of  the  Brain,"  "  Lancet,"  1876-"77. 

*  "  Researches  on  the  Intimate  Structure  of  the  Brain,"  "  Phil.  Trans.,"  London, 
1868  and  1868. 

'  "  Die  Leitungsbahnen  im  Gehim  und  RUckenmark  des  Menschen." 

8  "  Functions  of  the  Brain,"  New  York,  1882. 

»  »  Bull,  de  la  Soc.  Anat.,"  1861. 

'*•  "  Recherches  exp^rimentales  sur  les  fonctions  du  cerveau."     "Jour,  de  Physiolo 
gie,"  Paris,  1830.     "Trait6  de  I'Encdphalite,"  Paris,  1825. 
»  "  CUnique  M6dicale." 


GENERAL  INTRODUCTION.  5 

function,  the  eye-  no  longer  be  capable  of  vision,  the  ear  no 
longer  perceive  sound,  and  that  smell,  taste,  expression,  and 
movement  would  cease  to  exist,  we  can  then  understand  how 
much  of  physiological  interest  must  center  around  this  special 
study,  and  how  necessary  is  the  thorough  understanding  of 
the  distribution  and  function  of  the  individual  nerves,  if  we 
ever  hope  to  attain  a  comprehensive  grasp  of  the  general  plan 
of  our  construction. 

During  the  last  session,  I  closed  my  course  of  lectures  with 
a  description  of  the  general  construction  of  nerves  and  the 
anatomy  of  the  human  brain.  It  will  assist  us,  in  our  study 
of  the  distribution  and  practical  utility  of  the  separate  nerves 
of  the  body,  to  hastily  review  the  main  classifications  of 
nerves  and  the  general  plan  upon  which  the  nervous  system 
is  formed. 

The  nervous  system  of  the  human  race  consists  of  the  fol- 
lowing component  parts : 

(  The  cerebro-spinal  axis,  . 
1st.  Cerebro-spinal  system.  •<  The  motor  nerves. 

(  The  sensory  nerves. 
2d.  The  sympathetic  nerve  and  its  vaso-motor  connections. 
3d.  Various  ganglia,  connected  with  special  nerves. 


Fig.  1. — Nerve  fibers  from  the  human  subject ;  magnified  Z^O  diameters.     (Kolliker.) 

Four  small  fibers,  of  which  two  are  varicose,  one  medium-sized  fiber  with  borders  of  single 
contour,  and  four  large  fibers  ;  of  the  latter,  two  have  a  double  contour  and  two  con- 
tain granular  matter. 


GENERAL  INTRODUCTION. 


Fio.  2. — Cervical  and  thoracic  portion  of  the  sympathetic.     (Sappey.) 

1,  1,  1,  right  pneumogastric ;  2,  glosso-pharyngeal ;  3,  spinal  accessory;  4,  divided  trunk 
of  the  sublingual ;  5,  5,  5,  chain  of  ganglia  of  the  sympathetic  ;  6,  superior  cervical 
ganglion  ;  7,  branches  from  this  ganglion  to  the  carotid ;  8,  nerve  of  Jacobson ;  9, 
two  filaments  from  the  facial,  one  to  the  spheno -palatine  and  the  other  to  the  otic  gan- 
glion ;  10,  motor  oculi  externus ;  11,  ophthalmic  ganglion,  receiving  a  motor  filament 
from  the  motor  oculi  communis  and  a  sensory  filament  from  the  nasal  branch  of  the 


GENERAL  INTRODUCTION.  7 

fifth  ;  12,  spheno-palatine  ganglion  ;  13,  otic  ganglion  ;  14,  lingual  branch  of  the  fifth 
nerve;  15,  mhmaxillary  ganglion;  16,  17,  superior  laryngeal  nerve;  18,  external 
laryngeal  nerve;  19,  20,  recurrent  laryngeal  nerve;  21,  22,  23,  anterior  branches  of 
the  upper  four  cervical  nerves^  sending  filaments  to  the  superior  cervical  sympathetic 
ganglion  ;  24,  anterior  branches  of  the  fifth  and  sixth  cervical  nerve  sending  filaments 
to  the  middle  cervical  ganglion  ;  25,  26,  anterior  branches  of  the  seventh  and  eighth 
cervical  and  the  first  dorsal  nerves^  sending  filaments  to  the  inferior  cervical  ganglion  ; 
2*7,  middle  cervical  ganglion  ;  28,  cord  connecting  the  two  ganglia  ;  29,  inferior  cervi- 
cal ganglion  ;  30,  SI  ^filaments  connecting  this  loith  the  middle  ganglion  ;  32,  superior 
cardiac  nerve  ;  33,  middle  cardiac  nerve  ;  34,  inferior  cardiac  nerve  ;  35,  35,  cardiac 
plexus  ;  36,  ganglion  of  the  cardiac  plexus  ;  37,  nerve  following  the  right  coronary 
artery  ;  38,  38,  intercostal  nerves  with  their  tivo  filaments  of  communication  with  the 
thoracic  ganglia;  39,  40,  41,  great  splanchnic  nerve;  42,  lesser  splanchnic  nerve; 
43,  43,  solar  plexus  ;  44,  left  pneumogastric ;  45,  right  pneumogastric ;  46,  lower  end 
of  the  phrenic  nerve  ;  47,  section  of  the  right  bronchus  ;  48,  arch  of  the  aorta ;  49, 
right  auricle;  50,  right  ventricle;  51,  52,  pulmonary  artery;  53,  right  half  of  the 
stomach  ;  54,  section  of  the  diaphragm. 

The  CEEEBRO-spiNAL  SYSTEM  includes,  as  its  first  com- 
ponent part,  those  nerve- centers  inclosed  within  the  cavities 
of  the  cranium  and  spinal  column,  viz.,  the  cerebrum,  cerebel- 
lum, crus,  pons  Varolii,  medulla  oblongata,  and  spinal  cord. 

The  second  component  part  of  the  system,  viz.,  the  motor 
nerves,  are  efferent  nerves^  which  carry  the  impulses  of  the 
nerve-centers  to  the  muscles. 

The  third  component  part,  the  sensory  nerves,  are  afferent 
nerves^  which  carry  only  sensory  impressions  from  the  pe- 
riphery of  the  body  to  the  nerve-centers,  viz.,  to  the  brain  or 
spinal  cord. 

The  cerebro-spinal  nerves  are  usually  found  in  company 
with  the  larger  blood-vessels.  They  are  protected  from  injury 
either  by  investing  muscular  layers,  or,  when  near  the  sur- 
face, by  the  lines  of  flexion  of  the  joints. 

It  is  worthy  of  remark  that  the  foramina  of  exit  of  the 
cranial  nerves  from  the  base  of  the  skull  are  less  liable  to 
variation  than  those  for  the  transmission  of  blood-vessels. 

The  SYMPATHETIC  NERVE '  comprises  a  continuous  chain  of 
nerve-fibers  and  ganglionic  enlargements,  which  extends  from 
the  head  to  the  coccyx,  on  both  sides  of  the  spinal  column, 
and  which  is  in  constant  communication  along  its  course 
with  branches  of  the  cerebro-spinal  system  of  nerves.  It  sup- 
plies branches  to  various  ganglia  of  the  thorax  and  abdomen, 
and  helps  to  form  plexuses  of  nerves  which  ramify  upon 

*  See  Fig.  2  and  Fig.  3. 


8 


GENERAL  INTRODUCTION. 


kLVtULidil. 

Fio.  3. — Lumbar  and  sacral  poi 


E.  SALLE  10. 

>j  the  sympathetic. 


(Sappey.) 


1,  section  of  the  diaphragm ;  2,  lower  end  of  the  oesophagus ;  3,  left  half  of  the  stomach ; 
4,  small  intestine ;  6,  sigmoid  flexure  of  the  colon ;  6,  rectum ;  7,  bladder ;  8,  pros- 
tate ;  9,  lower  end  of  the  left  pncumogastric ;  10,  lower  end  of  the  right  pneumogas- 
tric;  11,  solar  jAexits  ;  12,  longer  end  of  the  great  splamhnic  nerve  ;  13,  lower  end  of 
the  letter  splanchnic  nerve  ;  14,  14,  last  two  thoracic  ganglia  ;  15,  16,  the  four  lumbar 
ganglia;  16,  16,  17,  17,  branches  from  the  lumbar  ganglia  ;  18,  f.upanor  mesenteric 
plexus  ;  19,  21,  22,  23,  aortic  lumbar  plcrus  ;  20,  inferior  mesenteHc  pfcxvs  ;  24,  24, 
sacral  portion  of  the  symjMthctic  ;  26,  26,  26,  26,  27,  27,  h/ftogastric  plexus  ;  28,  29, 
30,  tenth,  eleventh,  and  twelfth  dorsal  nerves  ;  81,  82,  83,  34,  35,  36,  37,  38,  39,  lum- 
bar and  sacral  nerves. 


•  X 


?  'i 


GENERAL  INTRODUCTION.  9 

the  coats  of  all  the  principal  blood-vessels,  and  which  accom- 
pany them  throughont  the  length  of  their  course.  It  is  by 
means  of  these  plexuses  upon  the  blood-vessels  that  the  sym- 
pathetic nerve  is  enabled  to  control  the  involuntary  muscular 
fibers  within  the  coats  of  the  blood-vessels,  and  thus  to  regu- 
late the  vascular  supply  of  the  various  tissues  and  organs  of 
the  body.  The  nerve-fibers  of  the  sympathetic  are  therefore 
often  called  the  ''nerves  of  organic  life,"  since  they  regulate 
the  life  of  tissues  by  controlling  their  blood  supply ;  while 
the  cerebro  -  spinal  nerves  are  contradistinguished  as  the 
''nerves  of  animal  life,"  since  they  control  those  acts  which 
are  essential  to  the  life  of  the  individual,  such  as  muscular 
movement,  respiration,  etc.  The  frequent  communication  be- 
tween the  sympathetic  nerves  and  those  of  the  cerebro-spinal 
system  renders  the  actions  of  the  two  systems  in  perfect  ac- 
cord, and  thus  supports  the  universal  law  of  harmony  which 
is  so  beautifully  illustrated  in  all  the  works  of  Nature. 

Interspersed  along  the  paths  of  the  motor  and  sensory 
nerve- tracts,  within  the  substance  of  the  brain  and  spinal 
cord,  special  centers  connected  with  sympathetic  nerve-fibers 
have  been  demonstrated — the  so-called  vaso-motor  centers. 

The  exact  situation  and  limits  of  these  centers  are  still  a 
matter  for  future  investigation.  We  know,  however,  that 
the  brain  and  spinal  cord  is  capable  of  transforming  afferent 
or  sensory  impulses  into  efferent  vaso-motor  impulses,  which 
create  either  constriction  or  dilatation  of  blood-vessels.  Some 
of  the  vaso-motor  fibers  run  in  the  larger  nerves  of  the  cere- 
bro-spinal system.  As  an  illustration  of  this  fact,  erection  of 
the  penis  may  be  artificially  produced  by  stimulation  of  sen- 
sory surfaces,  the  blood-vessels  of  that  organ  becoming  dilated 
to  an  enormous  extent  as  a  result  of  the  sensory  impulses 
transmitted  to  the  spinal  cord.  Experiments  of  a  similar 
character  made  upon  the  trunks  of  cerebro-spinal  nerves 
have  manifested  the  effects  of  stimulation  in  dilatation  of 
blood-vessels  of  the  limbs. 

We  know,  also,  that  the  brain  and  spinal  cord  exercise  a 
so-called  '''trophic  action''^  upon  the  joints,  skeletal  muscles, 


10  GENERAL  INTRODUCTION. 


I 


and  other  tissues,  governing  their  nutrition  and  growth,  and 
causing  them  to  respond  in  the  proper  way  to  the  demands 
made  upon  them  by  the  strains  and  shocks  of  daily  life. 

We  are  compelled,  therefore,  to  divide  the  vasomotor 
nerves  into  two  classes,  the  vaso-dilator  and  vaso-constrictor. 
The  former  allow  of  vascular  dilatation,  and  excess  of  blood 
to  the  part  supplied  by  the  nerve  affected  or  called  into  action 
is  the  result  of  impulses  transmitted  by  these  fibers.  The 
latter  have  an  opposite  action,  the  vessels  being  diminished 
in  caliber  and  the  blood  supply  to  the  part  being  proportion- 
ately decreased.  These  nerves  will  be  considered  in  detail 
later  in  the  course. 

The  CEREBRO-SPiNAL  NERVES  Comprise  (1)  those  which 
escape  from  the  foramina  of  the  cranium,  called  the  cranial 
nerves ;  and  (2)  those  which  are  given  off  from  the  spinal 
cord.  The  latter  escape  from  the  spinal  canal  by  means  of 
foramina  between  the  laminae  of  the  vertebrae,  called  the 
*4nter- vertebral  foramina."  These  are  called  spinal  nerves^ 
in  contradistinction  to  the  cranial  nerves. 

All  of  the  spinal  nerves  arise  by  two  roots.,  thus  indicating 
that  they  are  provided  with  both  motor  and  sensory  fila- 
ments. The  former  constitute  the  anterior  and  the  latter  the 
posterior  root. 

The  cranial  nerves  are,  in  some  instances,  similarly  con- 
structed ;  having  two  distinct  roots.  Others  have  only  one. 
The  reason  of  this  anatomical  variation  is  explained  by  the 
fact  that  some  of  the  cranial  nerves  are  destitute  of  motor 
fibers,  some  of  sensory  fibers,  while  others  are  endowed  with 
a  special  function,  such  as  sight,  smell,  hearing,  and  taste. 

Motor-nerve  fibers  differ  from  sensory -nerve  fibers  in  re- 
spect to  their  method  of  origin  and  termination.  It  may  be 
stated  that  motor  fibers  begin  and  end  in  masses  of  proto- 
plasm (nerve-cells  or  nerve-plates).  Sensory  nerves  appear  to 
arise  within  the  spinal  cord  from  a  net-worJc  of  fibers^  whose 
connections  with  the  sensory  cells  of  the  cord  are  not  as  yet 
positively  determined.  They  terminate  either  in  a  plexus  of 
nerve-endings,  loops,   tactile  corpuscles,  or  in  some  of  the 


GENERAL  INTRODUCTION, 


11 


apparatuses  connected  with  tlie  special  senses  of  smell,  hear- 
ing, or  sight. 

In  the  course  of  lectures  which  I  propose  to  deliver  before 
you  this  winter,  it  is  my  intention  not  only  to  give  the  ana- 
tomical origin,  course,  and  distribution  of  the  various  nerves, 
but  also  such  points  of  practical  value  as 
may  be  suggested  in  connection  with  each ; 
these  will  aid  in  remembering  the  peculiari- 
ties which  each  presents,  and  possibly  guide 
you  often  in  your  practice  at  the  bedside  of 
the  sick. 

The  study  of  the  practical  bearing  of  the 
distribution  of  the  nerves  is  to-day  assum- 
ing an  importance  in  diagnosis  which  can 
not  be  over-estimated  ;  since  the  physiologi- 
cal phenomena  produced  by  them  have  a 
direct  influence  upon  the  proper  perform- 
ance of  all  those  functions  of  the  body 
which  may  be  considered  as  vital  to  it. 

It  is  claimed  by  John  Hilton'  that,  if 
we  trace  the  distribution  of  the  motor  nerve 
filaments  from  any  special  nerve  trunk  to 
the  muscles,  we  shall  find  that  only  those 
muscles  are  supplied  by  each  of  the  indi- 
vidual nerves  which  are  required  to  render 
the  performance  of  the  functions^  for  which 
that  nerve  was  designed,  complete  ;  and  that, 
if  muscles  were  classified  on  a  basis  of  their 
nerve  supply,  instead  of  in -groups  of  mere  relationship  as 
to  locality,  a  self-evident  physiological  relation  would  be 
shown  which  would  tend  greatly  to  simplify  a  knowledge  of 
the  muscular  system  in  its  practical  bearings,  and  to  prove 
a  design  on  the  part  of  the  Creator. 

Thus,  he  says,  we  frequently  find  muscles  close  together 
and  still  supplied  by  separate  nerves,  one  of  which  has  possi- 
bly to  go  a  long  way  out  of  a  direct  course  to  reach  it,  which 


Fig.  4, — Fibers  of 
Remak  ;  magni- 
fied 300  diame- 
ters.    (Robin.) 

With  the  gelatinous 
fibers  are  seen 
two  of  the  ordina- 
ry, dark-bordered 
nerve-fibers. 


"  Rest  and  Pain,"  London.     (New  York,  1879.) 


12 


GENERAL   INTRODUCTION. 


is  contrary  to  the  usual  method  of  Nature,  who  always  em- 
ploys the  simplest  means  to  accomplish  her  designs ;  but,  if 
we  examine  the  action  of  these  two  muscles,  we  shall  find 
that  each  one  acts  in  unison  with  the  other  muscles  supplied 
hy  the  same  nerve,  and  that  to  produce  this  perfect  accord 
Nature  takes  what,  to  a  hasty  glance,  would  seem  to  be  a 
needless  step. 


Fig.  6. — Mode  of  termination  of  the  motor  nej-ves.     (Rouget.) 

A,  primitive  fasciculus  of  the  thyro-hyoid  muscle  of  the  human  subject  and  its  nerve 

tube:  1,  1,  primitive  muscular  fasciculus;  2,  nerve  tube;  3,  medullary  substance  of 
the  tube,  which  is  seen  extending  to  the  terminal  plate,  where  it  disappears ;  4,  ter- 
minal plate  situated  beneath  the  sarcolcmma,  that  is  to  say,  between  it  and  the  ele- 
mentary fibrillae ;  5,  5,  sarcolemma. 

B,  primitive  fasciculus  of  the  intercostal  muscle  of  the  lizard,  in  which  a  nerve  tube  ter- 

minates: 1,  1,  sheath  of  the  nerve  tube;  2,  nucleus  of  the  sheath ;  3,  3,  sarcolemma 
becoming  continuous  with  the  sheath  ;  4,  medullary  substance  of  the  nerve  tube  ceas- 
ing abruptly  at  the  site  of  the  terminal  plate ;  5,  5,  terminal  plate ;  6,  6,  nuclei  of 
the  plate ;  7,  7,  granular  substance  which  forms  the  principal  element  of  the  terminal 
plate,  and  which  is  continuous  with  the  axis  cylinder;  8,  8,  undulations  of  the  sarco- 
lemma reproducing  those  of  the  fibrillae ;  9,  9,  nuclei  of  the  sarcolemma. 

He  also  lays  down  certain  axioms,  pertaining  to  the  distri- 
bution of  nerves  and  the  diagnostic  value  of  pain,  which  will 
be  often  repeated  in  these  lectures,  and  can  not  but  be  most 
profitable  to  those  who  use  them  as  a  guide.  They  are  as 
follows : 

^^Superficial  pains  on  both  sides  of  the  body,  which  are 
symmetrical,  imply  an  origin  or  cause,  the  seat  of  which  is 
central  or  bilateral;  while  unilateral  pain  implies  a  seat  of 
origin  which  is  one-sided,  and,  as  a  rule,  exists  on  the  same 
side  of  the  body  as  thepainP 

The  bearings  of  this  first  axiom  will  be  rendered  far  more 
apparent  when  the  regions  of  the  neck  and  trunk  are  con- 


GENERAL  INTRODUCTION.  13 

sidered,  since  the  symptom  of  local  pain  is  of  the  greatest 
value  in  connection  with  diseases  affecting  the  bones  of  the 
spinal  column  and  the  spinal  cord  which  they  invest ;  but  the 
same  rule  may  be  applied  to  any  of  the  cranial  nerves,  with  a 
degree  of  certainty  which  seldom  admits  of  error. 

Thus  Hilton  reports  a  case  where  a  fracture  of  the  base  of 
the  skull,  involving  the  orbit,  produced  amaurosis  and  tension 
of  that  region,  with  extreme  local  pain.  A  grooved  probe, 
passed  along  the  root  of  the  orbit,  revealed  pus,  as  was  sus- 
pected to  exist.  This  was  evacuated  by  the  separation  of  the 
blades  of  an  ordinary  dressing  forceps. 

As  further  examples  of  this  axiom,  a  toothache  may  ac- 
company an  inflamed  condition  of  the  temporo-maxillary 
articulation,  or  it  may  create  it.  Again,  opium  introduced 
into  the  auditory  canal  will  often  instantaneously  relieve 
toothache  and  stiffness  of  the  jaws,  by  having  a  narcotic 
effect  upon  the  peripheral  filaments  of  the  same  nerves,  whose 
main  trunks  are  distributed  to  the  regions  mentioned  as  re- 
lieved. 

Severe  earache  may  result  directly  from  the  nervous  irri- 
tation of  a  diseased  tooth,  since  the  filaments  of  the  fifth 
nerve  are  distributed  to  both  the  ear  and  the  teeth,  and  thus 
pain  may  be  felt  at  a  point  apparently  disconnected  from  the 
seat  of  irritation. 

Earache  is  frequently  the  result  of  malignant  ulceration 
of  the  tongue,  since  both  regions  receive  a  portion  of  their 
nervous  supply  from  the  fifth  cranial  nerve. 

The  second  axiom  is  as  follows  : 

''The  same  trunlcs  of  nerms,  whose  branches  supply  the 
groups  of  muscles  moving  a  joints  furnish  also  a  distribution 
of  nerves  to  the  sMn  over  the  insertions  of  the  same  muscles  ; 
and  the  interior  of  the  joint  moved  by  these  muscles  receives 
a  nerve  supply  from  the  same  source?'' 

By  this  axiom,  a  physiological  harmony  is  created  between 
these  various  cooperating  structures.  Thus  any  Joint,  when 
inflamed,  may,  by  a  reflex  act  through  motor  branches  de- 
rived from  the  same  trunk  by  which  it  is  itself  supplied,  con- 


14  GENERAL  INTRODUCTION. 

trol  the  muscles  which  move  it,  and  thus  insure  the  rest  and 
quiet  necessary  to  its  own  repair. 

Spots  of  local  tenderness  in  the  cutaneous  surface  may, 
for  this  reason,  likewise  be  often  considered  as  a  guide  to  a 
source  of  irritation  of  some  of  the  structures  supplied  by  the 
same  nerve,  viz.,  the  muscles  underneath  it,  or  the  joints 
which  are  moved  by  them  ;  and  thus  even  remote  affections 
can  be  accurately  determined,  which,  were  this  axiom  not 
used  as  a  guide,  might  escape  recognition  till  an  advanced 
stage  of  the  disease  had  been  reached. 

The  distribution  of  nerves  to  the  under  surface  of  muscles 
seems  to  be  a  rule,  as  Hilton  points  out,  with  comparatively 
few  exceptions  It  is  stated  by  Allen  that  the  external 
oblique  muscle  of  the  abdomen  and  the  abductor  pollicis  are 
exceptions. 

The  shape  of  muscles  seems  to  determine  the  method  of 
nerve- endings,  as  was  first  pointed  out  by  Schwalbe.  Those 
muscles  whose  width  exhibits  little  variation  and  whose  fibers 
run  parallel  with  one  another  receive  only  one  nerve,  which 
enters  at  its  middle  point.  Those  muscles  that  are  of  a  tri- 
angular form,  and  whose  fibers  converge  toward  a  tendon  at 
its  apex,  receive  the  nerve  near  to  the  attachment  of  the 
tendon.  Hilton's  axioms  of  nerve  distribution  relate  to  the 
physiological  distribution  of  nerves  to  muscles  and  the  adja- 
cent skin. 

It  is  well,  however,  to  quote  one  other  axiom,  laid  down 
by  the  same  author,  before  leaving  the  subject  of  the  diag- 
nostic value  of  the  cutaneous  nerves  as  indicators  of  existing 
disease  of  other  organs,  viz. : 

''^ Every  fascia  of  the  body  has  a  muscle  or  muscles  at- 
tached to  it^  and  every  fascia  must  he  considered  as  one  of^^ 
the  points  of  insertion  of  the  muscles  connected  to  it,  in  folH 
lowing  the  previous  axiom  as  to  the  cutaneous  distribution 
of  nerves." 

This  guide  is  especially  important  in  case  the  rule  should 
be  applied  to  the  extremities  (arms  and  legs)  where  these 
fasciae  extend  over  large  surfaces,  more  or  less  remote  from. 


GENERAL  INTRODUCTION,  15 

and  apparently  unconnected  with,  the  muscles  attached  to 
them ;  but  it  is  mentioned  in  this  connection,  for  the  special 
object  of  calling  your  attention  to  those  general  rules  which 
govern  the  distribution  of  the  nerves  in  their  entirety,  before 
proceeding  to  apply  them  in  all  their  individual  bearings. 

Without  this  nervous  association  between  the  muscular 
structures  and  those  composing  the  joints,  there  could  be  no 
intimation  given  by  the  internal  parts  of  their  exhaustion  or 
fatigue.  Again,  through  the  medium  of  this  same  association 
between  the  skin  and  the  muscles,  great  security  is  given  to 
the  joints,  by  the  muscles  being  made  aware  of  the  point  of 
contact  of  any  extraneous  force  or  violence.  Their  involun- 
tary contraction  instinctively  makes  the  tissues  surrounding 
the  joints  tense  and  rigid,  and  this  brings  about  an  improved 
defense  for  the  subjacent  joint  structures. 

From  the  conclusion  of  his  great  work,  in  which  Hil- 
ton '  endeavors  to  prove  that  mechanical  rest  may  be  used 
as  a  cure  for  most  of  the  surgical  disorders,  the  follow- 
ing sentences  are  quoted,  since  they  can  not  be  too  often 
repeated : 

''I  have  endeavored  to  impress  upon  you  the  fact  tliat 
every  pain  has  its  distinct  and  pregnant  signification  if  we 
will  hut  carefully  search  for  it. 

"  From  the  pain  which  follows  the  intrusion  of  a  jjarticle 
of  dust  on  to  the  conjunctiva,  and  the  closure  of  the  eyelid 
for  the  security  of  rest,  up  to  the  most  formidable  diseases 
which  we  have  to  treat,  pain  the  monitor,  and  rest  the  cure, 
are  starting-points  for  contemplation,  which  should  ever  be 
present  to  the  mind  of  the  surgeon." 

In  studying  the  nervous  system  of  man,  the  special  consid- 
eration of  the  brain  should  first  engage  our  attention,  because 
it  is  by  far  the  most  difficult  to  thoroughly  comprehend. 
Subsequently  each  of  the  twelve  nerves  of  the  cranium  which 
arise  from  the  brain-substance  should  be  reviewed,  and  the 
more  important  facts  presented  by  each,  which  may  tend  to 
elucidate  its   function  or  explain   many  direct   and   reflex 

1  op.  cit. 


16  GENERAL  INTRODUCTION. 


phenomena,  should  be  understood.     These  are  often  of  great 
value  in  the  diagnosis  of  obscure  affections. 

Later  in  the  course,  the  anatomy  of  the  spinal  cord  and 
the  nerves  which  arise  from  it  should  be  investigated ;  noting, 
in  each  instance,  such  points  as  tend  to  elucidate  the  function  5« 
of  the  part  under  consideration,  and  also  such  clinical  facts  \ 
as  can  be  constantly  applied  in  your  daily  association  with  \ 
the  sick,  when  difficult  questions  of  diagnosis  arise,  or  when  ^ 
valuable  suggestions,  as  to  the  methods  of  treatment  employed,  ] 
seem  to  be  the  direct  outgrowth  of  your  anatomical  study.         ^ 

It  has  become  rather  an  established  custom  with  late    ^ 
authors  to  reverse  this  order  of  study,  as  they  commonly      j 
direct  the  attention  of  their  readers  first  to  the  construction      ] 
of  the  spinal  cord,  which  is  much  simpler  than  that  of  the     k 
brain.     They  then  trace  the  nerve-strands  which  compose  it      , 
upward  to  their  connections  with  the  various  parts  of  the      j 
brain.     It  must  be  acknowledged  that  this  system  has  some 
advantages  over  the  one  which  I  shall  adopt ;  but  it  has  also, 
to  my  mind,  certain  disadvantages  which  have  caused  me  to 
vary  from  the  more  common  method  of  description.    In  order      \ 
to  avoid  any  possibility  of  confusion,  however,  I  shall  begin 
my  course  with  a  general  description  of  cerebral  and  spinal      i 
architecture.     The  diagrams  which  I  shall  employ  to  ill  us-      ; 
trate  this  portion  of  the  course  will,  I  trust,  prove  of  great     ^ 
service  (Figs.  7,  8,  9,  and  10).  '/I 

Some  years  since,  my  friend  Prof.  E.  C.  Seguin  ad-  ■  J 
dressed  a  class,  in  beginning  a  course '  upon  a  somewhat 
similar  subject,  with  words  of  counsel  and  earnest  pleading 
for  higher  professional  attainments,  which  are  well  worthy  of 
repetition.  I  therefore  quote  them  to  you  in  the  same  spirit, 
trusting  that  they  will  kindle  in  you  a  renewed  vigor  and 
enthusiasm  in  this  special  department  of  science : 

*'  In  practice,  when  we  have  completed  the  examination  of 
a  patient,  several  questions  are  put  to  us  by  the  patient,  by 
his  friends,  or  by  ourselves.     These  are,   in  chronological 

1  Delivered  before  the  students  of  the  College  of  Physicians  and  Surgeons  of  New 
York  City,  1878. 


GENERAL  INTRODUCTION.  17 

order :  Is  there  disease  ?  Where  is  the  disease  ^  What  is 
the  disease  ?  What  are  we  to  do  for  the  cure  of  the  disease 
or  for  the  relief  of  the  patient?  Will  the  patient  die  or 
recover  ? 

''Of  these  questions,  the  one  which  our  client  and  the 
world  at  large  consider  the  most  important  is  the  fourth — that 
relating  to  treatment  and  cure.  This  preference  is  natural, 
but  highly  unscientific ;  it  is  a  manifestation  of  that  untrained 
mental  action  which  demands  results  and  scorns  methods, 
which  welcomes  empirical  achievements  (provided  they  be 
agreeable),  and  which  conduces  to  the  perpetuation  of  quack- 
ery of  all  kinds.  But  to  the  physician  who  is  not  a  mere  pre- 
scription writer,  who  aims  at  infusing  as  much  science  into 
his  practice  as  possible,  and  who  believes  that  he  is  not  in 
the  world  for  the  purpose  of  gratifying  his  patients  at  so 
much  per  visit,  but  that  he  owes  himself  a  debt  of  training 
and  self- culture,  and  who  has  a  sincere  regard  for  science — to 
such  a  physician  the  first  three  questions  assume  a  justly 
great  importance.  Pray  observe  that  I  do  not  say  paramount 
importance,  but  great  importance.  And  the  superiority  of 
the  humanitarian  over  the  scientific  duty  becomes  less  glaring 
if  we  bear  in  mind  the  truth — and  I  firmly  believe  it  to  be 
such  —  that  success  in  treatment  now  depends,  and  in  the 
future  will  still  more  closely  depend,  upon  the  scientific  study 
of  the  human  subject  in  health  and  disease.  In  other  words, 
I  would  impress  you  with  my  own  conviction  that  the  best- 
trained  and  most  scientific  physician,  if  he  be  not  a  closet 
student  and  theorizer,  is  the  best  practitioner. 

"  We  occasionally  hear  of  an  over-fine  diagnosis,  of  ex- 
treme caution  in  the  treatment  of  disease,  and  of  the  sweep- 
ing application  of  physiological  laws  to  practice  by  men  who 
are  said  to  be  *  too  scientific ' ;  but  who  can  number  the  errors, 
nay,  the  sacrifices  of  life,  which  must  be  laid  at  the  door  of 
the  falsely  so-called  'practical  men,'  who  despise  learning 
and  scientific  methods  ?  Those  of  us  who  see  something  of 
the  rarer  and  more  formidable  kinds  of  disease  fully  realize 
that  in  medicine,  as  probably  in  other  applicable  sciences, 


18  GENERAL  INTRODUCTION. 

ignorance  leads  to  rashness  and  crudity  in  practice,  while  ripe 
knowledge  conduces  to  success,  or,  at  any  rate,  to  caution  in 
prognosis  and  expectancy  in  treatment. 

"Of  the  three  diagnostic  questions  — Is  there  disease? 
Where  is  the  disease  ?  What  is  the  disease  ? — the  second  is 
the  one  which  forms  the  key  note  of  these  lectures.  Where 
is  the  lesion  producing  the  disordered  actions  or  symptoms  \ 
The  method  to  be  followed  in  arriving  at  the  solution  of  this 
question  varies  somewhat  in  different  departments  of  medi- 
cine. Some  lesions  can  be  seen  by  the  trained  unaided  eye, 
or  felt  by  the  skilled  hand  ;  the  seat  of  others  can  be  deter- 
mined by  auscultation  and  percussion,  by  the  aid  of  instru- 
ments, such  as  the  ophthalmoscope,  laryngoscope,  speculum, 
etc.  But,  in  the  study  of  the  nervous  system,  greater  diflScul- 
ties  are  met  with  ;  we  are,  to  a  great  extent,  deprived  of  these 
physical  aids ;  we  can  not  appreciate  the  condition  of  the 
brain  and  spinal  cord  directly  by  our  special  senses,  but  only 
by  a  proper  interpretation  of  the  way  in  which  the  functions 
of  these  parts  are  performed.  In  other  words,  the  diagnosis 
must  be  made  chiefly  by  reasoning." 

To  the  words  above  quoted,  I  can  add  nothing,  save  an 
earnest  endeavor  to  so  place  the  subject-matter  before  you  as 
to  render  it  within  the  grasp  of  your  full  comprehension,  pro- 
vided you,  in  turn,  earnestly  seek  to  master  it. 


THE  BRAIK  i 

ITS  ANATOMY,  FUNCTIONS,  AND  CLINICAL  ASPECTS  ] 


THE    BEAI]^ 


In  man  and  the  vertebrates,  the  cerebro-spinal  axis  may 
be  divided  into  three  separate  portions,  each  perfectly  inde- 
pendent of  one  another,  and  yet  very  intimately  connected. 
These  are  enumerated  by  Meynert  as  follows  : 

1.  The  cerebrum. 

2.  The  cerebellum,  and  the  apparatuses  of  cere- 
bellar INNERVATION   CONNECTED  WITH  IT. 

3.  The  medullary  portion  of  the  spinal  cord,  and 
ITS    expansions  to   the  different   parts    of   the   en- 

CEPHALON. 

The  nervous  system  of  all  animals  may  be  subdivided 
into  two  distinct  histological  elements,  nerve-cells  and  nerve- 
fibers.  The  former  may  be  compared  to  the  battery-cells  of 
an  electric  circuit ;  the  latter  to  the  wires  which  conduct  the 
current  generated  in  the  batteries. 

The  nerve- cells  are  the  chief  histological  elements  of  the 
so-called  ''gray  matter"  of  the  brain  and  spinal  cord,  and  of 
ganglia  found  in  other  parts ;  while  the  white  substance  of 
the  cerebro-spinal  axis  may  be  subdivided  by  the  microscope 
into  distinct  fibers,  which  serve  to  connect  the  nerve-cells  of 
some  particular  region  with  other  nerve- cells  or  with  the 
muscular  apparatus. 

Nervous  impulses  may  be  divided  into  two  classes :  cen- 
tripetal or  sensory^  and  centrifugal  or  motor. 

The  former  travel  from  the  peripheral  portions  of  the 
body  toward  the  nerve-centers ;  while  the  latter  cause  the 


22  THE  BRAIN. 

muscular  apparatus  of  the  body  to  act,  either  in  direct  re- 
sponse to  a  sensory  impression  received  from  without  {reflex 
movements)^  or  as  the  result  of  volition.  Microscopical  re- 
search enables  us  to  state  positively  that  both  of  these  two 
forms  of  nervous  impulses  are  conducted  partly  through 
direct  tracts  of  nerve-fibers,  and  partly  by  the  intercommuni- 
cation established  between  nerve-fibers  and  nerve-cells,  and 
nerve-cells  with  each  other. 

We  may  infer,  therefore,  that  nerve-cells  as  well  as  nerve- 
fibers  serve  to  maintain  isolated  conduction  of  nerve  impulses ; 
and  that  the  former  also  generate  and  in  some  instances  record 
them  (cells  of  memory).  We  find  the  morphological  expres- 
sion of  the  first  statement  in  the  fact  that  the  nerve- cells  lie 
with  their  long  axis  stretched  in  the  direction  of  the  nerve- 
fibers  with  which  they  are  connected ;  while  the  second  and 
third  propositions  are  established  by  physiological  research 
respecting  the  functions  of  different  regions  of  the  cerebral 
cortex,  as  well  as  by  the  general  arrangement  of  the  cell  ele- 
ments. We  are  forced,  moreover,  to  accord  to  the  nerve-cell 
the  functional  attribute  of  sensibility,  as  well  as  the  power 
of  generation  and  storage  of  nerve-force,  and  the  discharge 
of  this  unknown  power  in  the  form  of  motor  impulses. 

There  is  sufficient  ground  at  present  to  warrant  the  belief 
that  all  centripetal-  and  centrifugal- conducting  nerve-tracts 
are  prolonged  (in  spite  of  apparent  dismemberments  and 
reduplications  to  which  the  white  substance  of  the  cerebro- 
spinal system  is  subjected  in  passing  through  different  col- 
lections of  gray  matter  scattered  along  their  course)  to  the 
most  distant  centers  of  the  nervous  mechanism,  and  find  a 
direct  and  intimate  connection  with  the  nerve-cells  of  the 
gray  substance  of  the  cerebral  convolutions. 

It  seems  but  rational  to  assume  that  the  phenomena  of 
consciousness,  which  spring  purely  from  the  confluence  and 
union  of  the  various  processes  of  perception,  have  their  seat 
in  the  activity  of  the  cerebral  lobes;  to  which  all  the  cen- 
tripetal or  sensory  tracts  converge  and  from  which  all  the 
centrifugal  or  motor  tracts  arise. 


GRAY  MATTER   OF  THE  BRAIN.  23 

If  we  study  transparent  sections  of  the  brains  of  small 
mammals,  where  the  different  portions  are  more  clearly  de- 
fined than  in  animals  of  a  higher  type,  and  where  a  low 


Fig.  6. — Plan  in  outline  of  the  brain  in  profile.     (Quain.) 

The  cerebrum  is  represented  in  this  diagram  as  separated  from  the  cerebellum  more  than 
it  naturally  should  be,  in  order  to  show  certain  important  parts.  A,  the  cerebrum ; 
B,  the  cerebellum ;  C,  the  pons  Varolii ;  D,  the  medulla  oblongata ;  E,  the  crus 
cerebri ;  F,  the  olivary  body ;  G,  the  tubercula  quadrigemina ;  S,  the  fissure  of  Syl- 
vius ;  R,  the  fissure  of  Rolando ;  a,  peduncles  of  the  cerebrum ;  6,  superior  pedun- 
cles of  the  cerebellum  ;  c,  middle  peduncle  of  the  cerebellum ;  </,  inferior  peduncles 
of  the  cerebellum ;  6,  E,  a,  form  the  isthmus  encephali.  The  convolutions  of  the 
cerebrum  are  not  correctly  drawn  in  this  cut. 

magnifying  power  reveals  the  general  course  of  the  nerve- 
fibers  as  well  as  the  arrangement  of  the  masses  of  gray  mat- 
ter, we  are  enabled  to  grasp  some  general  features  of  con- 
struction which  are  applicable  to  the  brain  of  man. 

THE  GRAY  MATTER  OF  THE  BRAIN. 

We  find,  in  the  first  place,  that  the  nerve-cells  occur  in 
large  and  distinctly  isolated  masses,  which  may  be  thus 
enumerated : 

1.  The  gray  matter  of  the  exterior  of  the  cerebrum  (the 
cortex  cerebri)  that  invests  the  convolutions.  This  collection 
of  cells,  as  an  undulating  layer  folded  constantly  upon  itself, 
forms  a  layer,  marked  by  eminences  and  depressions  whose 
sole  object  is  to  obtain  an  increase  of  the  brain's  surface  over 
that  of  the  interior  of  the  cranium. 


24 


THE  BRAIN. 


I 


2.  Buried  within  the  substance  of  each  hemisphere  of  the 
cerebrum  may  be  found  two  nodal  masses  of  cells,  which  rest 
nearly  upon  the  level  of  the  floor  of  the  cerebrum,  and  which 
are  named,  from  their  contiguity  to  this  plane,  the  ''^ basal 
ganglia^ 


CORTEX 


°f^^fsrA 


Fig.  T. — A  diagram  designed  hy  the  author  to  elucidate  the  chief  component  parts  of 

the  human  brain. 

The  lettering  upon  the  figure  will  be  explained  in  the  text.  C.  Q.,  the  corpora  qiiadra- 
gemina,  or  "  optic  lobes."  The  lines  within  the  white  substance  of  the  cerebrum  or 
in  the  "  crus  "  arc  not  intended  to  convey  any  impression  to  the  reader  of  the  actual 
arrangement  of  the  fibers. 

Each  anterior  mass  is  called  the  ^^  corpus  striatum^'^^  from 
the  striated  appearance  of  a  section  made  through  its  sub- 
stance.* 

Each  posterior  mass  is  called  the  ''optic  thalamus ^^''  from 
a  supposed  association  with  vision  attributed  to  it  by  early 
investigators. 

'  This  ganglion  has  two  parts  (as  shown  in  Fig.  8) — the  caudate  nucleus,  and  lenticular 
nucleus.  These  parts  are  separated  by  a  bundle  of  nerve-fibers,  the  so-called  "  internal 
capsule  "  of  the  cerebrum. 


FIBERS  OF  TEE  CEREBROSPINAL  SYSTEM, 


25 


Fig.  8. — A  diagram  designed  hy  the  author  to  show  the  general  arrangement  of  the 
fibers  of  the  cerebrospinal  system.     (Modified  from  Landois.) 

The  shaded  portions  represent  the  collections  of  gray  matter.  On  the  left  side  of  the 
diagram,  the  sciisory  fibers  of  the  crus  are  traced  upward  from  the  spinal  cord  to 
different  portions  of  the  cerebrum ;  on  the  right  side,  the  motor  fiber's  are  similarly 
represented.  Numerals  are  used  in  designating  the  sensory  and  commissural  fibers  ; 
the  motor  fibers  are  lettered  in  small  type.  The  cortical  layer  is  shown  at  the 
periphery  of  the  cerebral  section,  with  commissural  fibers  (1)  connecting  homologous 
regions  of  the  hemispheres,  and  associating  fibers  {a.  s.)  connecting  different  convo- 
lutions of  each  hemisphere.  CS.,  caudate  nucleus  oi  the  coupus  striatum;  L.  N.,  len- 
ticular nucleus  of  the  same ;  0.  T.,  optic  thalamus  of  each  hemisphere,  united  to  its 
fellow  in  the  median  line ;  c.  9.,  corpora  quadrigemina  ;  c.  /.,  claustrum,  lying  to 
the  right  of  the  letters  ;  c.  c,  corpus  callosum,  with  its  commissural  fibers ;  S,  fis- 


26  ^  T'iTE'  BRAIK  ^^H^ 

SURE  OF  Sylvius  ;   F,  lateral  ventricle,  the  fifth  ventricle  being  shown  between  i 

the  two  layers  of  the  septum  lucidum  ;   C,  the  motor  tract  of  the  crus  cerebri  {basis  j 

oniris — crustd) ;   T,  the  seiisory  tract  of  the  CRUS  cerebri  {tegmentum  cruris) ;   C/",  j 

the  cei-ehellar  fasciculus,  which  is  turned  to  the  right  for  perspicuity,  but  which  in  i 

reality  decussates  ;  e,  the  point  of  decussation  of  the  motor  fibers  of  the  spinal  , 

cord;  /,  the  course  of  the  motor  Jihcrs  of  the  spinal  cord  below  the  medulla,  showing  I 

their  connection  with  the  cells  of  the  anterior  horns  of  the  gray  matter,  and  their  | 

continuation  into  the  anterior  roots  of  the  spinal  nerves  {g) ;  a,  fibers  which  radiate  ; 

through  the  caudate  nucleus ;  6,  fibers  of  the  "  internal  capsule " ;  c,  fibers  which  \ 
radiate  through  the  lenticular  nucleus  ;  J,  fibers  of  the  "  external  capsule  "  ;  2,  3,  4, 

5,  6,  7,  8,  9,  sensory  fibers  radiating  from  the  tegmentum  cruris  to  the  cortex  by  \ 
means  of  various  nodal  masses  of  gray  matter;  11,  course  of  the  sensory  fibers  of 

the  spinal  cord  (shown  by  dotted  lines),  intimately  connected  with  the  posterior  root  ' 

of  the  spinal  nerve  (12),  and  decussating  at  or  near  the  point  of  entrance  into  the  i 

spinal  cord.     This  diagram  may  be  studied  in  connection  with  Figs.  7,  9,  10,  11,  ; 

and  1 3,  with  possible  benefit  to  the  general  reader.  ! 

3.  The   cerebellum   presents   collections   of   gray  matter  ^ 
which  occur  partly  in  layers  {cerebellar  cortex)  and  partly  as 
scattered  masses  within  its  substance.  ^ 

4.  The  so-called  "tubular  gray  matter '^^  (which  may  be'^i? 
traced  as  a  lining  to  the  inner  portions  of  the  cerebro- spinal  ! 
axis '  from  the  tuber  cinereum  to  the  conus  meduUaris  of  the  . 
spinal  cord)  must  be  recognized  as  the  "  permanent  expression 

of  the  primitive  and  generic  type  of  brain." 

5.  Distinct  groups  of  cells  are  found  within  the  substance 

of  the  crus  cerebri,  the  pons  "Varolii,  and  the  medulla.    These  -^^ : 

will  be  discussed  later.  I 

The  diagram  (Fig.  8)  will  make  some  of  these  subdivisions  ■ 
of  the  gray  matter  of  the  cerebrum,  as  well  as  the  fibers 

which  connect  them,  more  apparent  than  a  long  verbal  de-  .^ 

scription.  .*;; 

It  will  be  seen  that  the  gray  matter  of  the   cortex  is^;' 

arranged  like  a  cap  to  the  brain,  and  embraces  the  '' basal  -'i^ 
ganglia,"  the  "claustrum,"  and  "corpora  quadrigemina"— iwl' 
intermediate  portions  being  left  which  in  the  brain  itself 

appear  as  a  white,  cheesy  mass.  These  are  filled  in  with  lines  \ 
in  the  diagram.     They  indicate  the  different  sets  or  "sy8-3B| 

tems"  of  nerve-fibers,  as  the  microscope  in  the  hands  of  late  j 

observers  has  shown  them  to  exist,  and  of  which  this  so-  1 

called  "white  substance''^  of  the  brain  is  chiefly  composed.  j 
[A  careful  study  of  the  text  accompanying  Figs.  8,  9,  and  10^ 


'  The  *'  ccrcbro-spinal  axis  "  is  a  term  used  to  include  the  brain  and  the  spinal  cord 
collectively. 


f 


J 


WHITE  MATTER   OF  THE  CEREBRUM. 


27 


will  enable  the  reader  to  grasp   tlie  general   direction  and 
terminations  of  the  sets  of  fibers  described.] 


Fig.  9. — Diagram  of  the  commissural  fibers  of  the  anterior  region  of  the  brain. 

(After  Luys.) 

These  form  a  series  of  curves  one  within  another,  the  extremities  of  each  of  which  plunge 
into  the  homologous  regions  of  each  cerebral  lobe,  1,  1',  2,  2',  3  and  3'.  They  pass 
through  the  middle  line,  and  at  4  and  4'  give  rise  to  the  various  appearances  which 
the  "  corpus  callosum "  presents.  5,  Commissural  fibers  of  the  inferior  regions. 
These  are  curved  in  an  inverse  direction  as  regards  the  former,  the  convexity  of 
each  set  being  presented  toward  that  of  the  other. 


THE   WHITE   MATTER   OF  THE   CEREBRUM. 

The  FIRST  SET  OF  FiBEES  (1  in  Fig.  8)  will  be  seen  to 
spring  from  the  cortex,  and,  after  taking  a  direction  which 
tends  to  bring  them  to  the  level  of  the  superior  point  of  nnion 
of  the  two  cerebral  hemispheres,  to  cross  over  to  the  side 
opposite  to  that  from  which  they  arise.  After  crossing,  they 
can  be  traced  to  homologous  regions  of  the  cortex  of  the 
opposite  hemisphere.  These  are  commonly  called  "commis- 
sural fiber s.^^  They  are  supposed  to  be  the  connecting  wires 
between  corresponding  portions  of  the  cortex  of  the  cerebral 
lobes,  by  the  aid  of  which  the  right  and  left  hemispheres  can 
act  in  unison  with  each  other  when  circumstances  chance  to 
demand  it. 

These  fibers  have  a  direction  which  corresponds  as  a  rule 
to  the  form  of  the  letter  U,  aiid  they  constitute  the  transverse 
fibers  of  the  "corpus  callosum^'' — the  connecting  band  of 
white  matter  between  the  hemispheres,  seen  at  the  bottom 


THE  BRAm. 


of  the  median  fissure  of  the  cerebrum  when  the  hemispheres 
are  separated.  Commissural  fibers  can  be  traced  also  between 
the  hemispheres  (in  certain  sections  of  the  brain)  as  an  infe- 
rior band '  which  lies  below  the  level  of  the  "basal  ganglia" 
(Fig.  10). 

There  is  reason  to  believe  that  these  connecting  fibers 
(which  form  nearly  if  not  quite  one  half  of  the  white  sub- 
stance of  the  cerebrum)  are  sufficient,  in  point  of  number,  to 
allow  of  an  anastomosis  of  the  gray  matter  of  the  cortex  of 
the  two  cerebral  lohes^  cell  to  cell.  In  infinite  numbers  they 
seem  to  spring  from  every  region  of  the  cortex — either  directly 
from  the  protoplasmic  structure  of  the  cell  elements,  or  as 
delicate  fibrils  which  can  be  traced  no  farther  than  the  inter- 
cellular structure,  where  their  delicate  sheaths  become  lost.^ 
(Luys.) 

The  SECOND  SET  OF  FIBERS  (Fig.  8)  to  which  I  would  now 
direct  attention  are  of  equal  importance  from  a  physiological 
point  of  view.  Originating  from  the  midst  of  a  plexus  of 
cells  in  the  cortex,  they  accompany  the  commissural  fibers 
to  the  point  where  the  former  diverge  to  the  opposite  hemi- 
sphere, after  which  a  separation  takes  place.  These  fibers 
do  not  pass  to  the  opposite  hemisphere^  but  concentrate  them- 
selves, in  the  region  of  the  superior  angle  of  the  ventricle, 
into  bundles  placed  in  close  juxtaposition.  Some  of  these 
fibers  are  inserted,  as  a  late  author  expresses  it,  like  "pins  in 
a  pin-cushion,"  into  the  basal  ganglia  of  the  hemisphere  from 
whose  periphery  they  take  their  origin.  Others  seem  to 
have  no  anatomical  relationship  with  the  basal  ganglia.  They 
are  known  as  the  "  capsular  fibers  "  ;  because  they  constitute 
a  capsule,  as  it  were,  for  the  lenticular  nucleus  (Fig.  8).  r 

The  second  set  of  fibers  (if  taken  collectively)  are  com^ 
monly  called  ''''radiating  fibers^''''  from  an  analogy  between 
the  direction  which  they  take  and  the  rays  of  light  reflected 
from  the  surface  of  a  hollow  sphere.     By  some  authors  they 


4«.l 


*  This  may  help  to  explain  the  fact  that  the  absence  of  the  corpus  callosum  has  in' 
exceptional  cases  been  observed  to  exist  without  any  apparent  abnormality  in  the  peft- 
formance  of  psychical  or  motor  phenomena  during  life.  f. 


RADIATING  FIBERS, 


29 


are  designated  as  ''  converging  fibers,''  because  they  tend  to 
become  focused  about  the  basal  ganglia.  By  others  the  term 
'' peduncular  fiber s  "  is  employed,  because  they  are  destined 
to  pass  into  the  crus  cerebri. 


)> 


y 


Fig.  10. — Diagram  of  the  commissural  fibers  on  the  levdofthe  corpus  striatum.   (Luys.) 

1,  1',  groups  of  transverse  fibers,  one  within  another,  continuous  with  those  in  the  pre- 
vious figure;  2,  2',  gray  substance  of  corpus  striatum;  3',  groups  of  inferior  com- 
missural fibers ;  4,  4',  these  curve  into  the  shape  of  an  8  to  accommodate  the  corpus 
striatum,  which  they  help  to  limit  externally. 

By  directing  our  attention  for  a  moment  to  the  fact  that 
fibers  which  are  distributed  to  all  portions  of  the  cortex  are 
forced  to  make  their  passage  from  and  into  the  spinal  cord 
through  the  foramen  magnum,  in  case  they  are  distributed 
to  parts  below  the  head,  we  shall  be  led  to  understand  why 
the  peduncular  set  are  properly  converging  fibers  before  they 
become  collected  into  the  circumscribed  limits  necessary  for 
their  transmission,  through  this  foramen  of  the  cranium,  to 
reach  the  spinal  cord. 

It  is  important  to  bear  in  mind  that  this  set  of  fibers  has 
nothing  in  common  with  the  opposite  hemisphere.  The  phys- 
iological function  of  the  peduncular  fibers  of  the  cerebrum 
consists  simj)ly  in  the  transmission  of  impulses  of  a  centripetal 
and  centrifugal  variety  to  and  from  the  cortex  cerebri.  It  is 
by  means  of  these  nerves  that  sensory  impressions  received 


30 


THE  BRAIK 


from  without  are  recorded  upon  tlie  sensory  portions  of  the  ; 
cortex,  and  motor  impulses  are  transmitted  from  the  motop^j 
regions  of  the  cortex  to  the  muscles  of  the  trunk  and  ex-Jt^^l 
tremities.  As  Meynert  aptly  puts  it,  ''the  sensory  nerve-  | 
fibers  constitute  the  feelers  of  the  cortical  cells,  the  motor  \ 
nerves,  the  tentacles,  as  it  were."  j 

A  THIRD  SET  OF  FIBERS  (Figs.  8  and  13)  exist  within  the  j 
white  substance  of  the  cerebral  lobes.  They  are  called  ''as-  | 
sociating  fibers'''*  {''fibres  arcuatce''^ — "  collateral  fibers  ^^).     \ 

c.c  ..  1 


Fio.  11. — A  diagram  to  Uhistrate  the  general  outline  of  the  corpus  callomm  and  the 
fornix.     (Modified  from  Allen.) 

?,  fornix,  extending  from  tip  of  temporal  lobe  to  the  base  of  the  brain,  anteriorly.  The 
cavity  of  the  third  ventricle  lies  below  its  middle  third.  C,  corpus  callosum,  form- 
ing the  roof  of  the  lateral  ventricles  and  merging  posteriorly  with  the  fornix ;  C.  C, 
cerebral  cortex ;  f.  M.,  foramen  of  Monro,  joining  the  lateral  ventricle  with  the  third 
ventricle ;  p.  f.,  anterior  pillar  of  the  fornix,  doubling  upon  itself  and  returning  to 
the  thalamus.     All  of  these  parts  will  be  described  in  detail  later  in  this  volume. 


These,  as  was  the  case  with  the  preceding  set,  are  confined 
exclusively  to  the  hemisphere  in  which  they  are  found.  They 
are  supposed  to  be  so  distributed  to  the  different  portions  of 
the  cortex  of  each  hemisphere  as  to  act  as  commissural  fibers 
for  the  different  cortical  centers.  Whether  they  are  always 
distinct  fibers,  or  simply  thread-like  anastomoses  of  the  ^yo- 
cesses  arising  from  the  cells  of  the  cortex,  is  not  as  yet  fully 
determined.  By  some  authors  these  fibers  are  described  as 
dipping  downward  for  some  distance  into  the  white  substance 
of  the  hemispheres  and  then  returning  to  the  cortex,  while 
others  describe  them  as  bundles  of  distinct  fibers  of  varying 
lengths  which  invest  the  inner  surface  of  the  cortex. 


THE  PROJECTION  SYSTEM.  31 

Finally,  attention  should  be  called  to  a  fourth  set  of 
FIBERS  tliat  apparently  serve  to  connect  the  cortex  of  the 
temporo-sphenoidal  lobes  with  the  optic  thalamus  by  taking 
an  arched  direction  over  that  ganglion,  and  then  dipping 
downward  to  the  base  of  the  brain  where  they  turn  upon 
themselves  and  pass  to  the  substance  of  the  thalamus.  Why 
these  so-called  '^ fornix  fiber s^^  should  take  this  circuitous 
route  in  order  to  establish  communication  between  the  basal 
ganglia  and  the  temporal  cortex  is  not,  as  yet,  understood. 
The  fornix  will  be  discussed  more  in  detail  in  subsequent 
pages.     It  is  shown  diagrammatically  in  Fig.  11. 

The  Projectioi^  Systems. — The  cerebral  cortex  or  the 
gray  matter  covering  the  convolutions  serves  as  a  receptacle 
for  the  various  impressions  of  the  external  world,  as  por- 
trayed to  it  by  means  of  the  nerves  of  sensation  and  the 
special  senses.  It  has  been  considered,  therefore,  by  Meynert 
as  analogous  to  a  projection  plane,  the  outer  world  being 
the  projected  object ;  and  the  nervous  system  has  been  sub- 
divided by  the  same  author  into  three  distinct  members  of  a 
so-called  '•'projection  system,^^  comprising  nerve-fibers  and 
various  ganglia  interposed  along  the  course  of  the  centripetal 
and  centrifugal  nerve-tracts.  The  views  of  this  author  may 
be  stated  as  follows  : 

The  first  merriber  of  the  projection  system  (Fig.  12)  con- 
sists of  the  fibers  which  are  connected  with  the  cortex  and 
which  terminate  chiefly  in  the  interrupting  gray  matter  of  the 
basal  ganglia. 

The  second  merriber  of  the  system  comprises  those  fibers 
of  the  crus  cerebri,  which  spring  from  the  basal  ganglia  and 
end  in  the  tubular  gray  substance.  These  fibers  terminate 
in  the  tubular  gray  substance  at  different  levels  in  order  to 
become  functionally  associated  with  different  parts  of  the 
body.  It  must  be  evident,  therefore,  that  the  length  of  these 
fibers  depends  entirely  upon  the  portion  of  the  periphery 
with  which  they  are  associated.  Most  of  these  fibers  are 
supposed  to  cross  the  median  line  to  reach  the  opposite  side 
of  the  spinal  cord. 


32 


THE  BRAIN. 


The  third  member  of  the  system  embraces  the  nerves  which 
arise  from  the  tubular  gray  matter ;  from  the  point  of  origin 
of  the  third  cranial  nerves  to  the  termination  of  the  spinal 

cord- 


Fiber  of 
superior  projec- 
tion sygbem.^'' 


Fiber  of 
Tniddle  projec- 
tion system.'''' 


Fiber  of 
inferior  projec- 
tion system.'''' 


Fio.  12. — A  schematic  representation  of  Meynerfs  three  projection  systems  of  n^rve-fbers. 


Spitzka's  classification  of  the  systems  of  projection  tracts 
and  the  ganglia  associated  with  them'  differs  from  that  of 
Meynert  (1)  in  that  he  numbers  them  in  accordance  with 
their  priority  of  development,  classing  the  central  tubular 
gray  and  the  spinal  nerves  as  the  first  projection  system  ; 
(2)  in  that  he  considers  the  gray  masses  of  the  reticular  for- 
mation of  the  medulla  (the  reticular  ganglion  of  this  author) 
as  belonging  to  a  special  category  ;  (3)  in  that  the  cerebellar 
system  is  incorporated  by  this  author  and  excluded  from  the 
plan  of  Meynert ;  and  (4)  that  the  number  of  the  projection 
systems  is  increased. 

*  "Jour,  of  Nervous  and  Mental  Diseases,"  Oct.,  18Y9. 


•    i 


SPITZKA'S  CLASSIFICATION. 


33 


There  is  much  to  be  said  in  favor  of  the  classification  of 
Spitzka,  although  it  is  perhaps  more  difficult  of  comprehen- 
sion to  the  minds  of  beginners  in  neuro-anatomy  because 
more  complete.  The  following  scheme  is  employed  by  that 
author  to  interpret  his  views  respecting  the  incorporation  of 
the  reticular  ganglion  in  the  projection  plan : 


RETICULAR  GANGLION 

OF  THE 

MEDULLA  OBLONGATA 


STRAND  UNITING  THE  RETICULAR  GANGLION 
WITH  THE  CENTRAL  TUBULAR  GRAY 


CENTRAL 
TUBULAR  GRAY 


<   PERIPHERAL  NERVE 


PERIPHERY. 

Space  will  not  allow  of  the  incorporation  of  all  the  ex- 
cellent diagrams  devised  by  this  author  to  illustrate  his 
views.    They  can  be  referred  to  in  the  article  from  which 


34 


THE  BRAIK 


the  above  is  taken.  One  other  will,  however,  be  intro- 
duced to  show  that  author's  views  respecting  the  com- 
munications between  the  ''reticular  ganglion"  and  J^he  nu- 
clei of  the  cranial  nerve-roots: 


2nd  Category 


RETICULAR  GANGLION 

OF  THE 

MEDULLA  OBLONGATA 


1st 
Category 


SECONDARY 

PROJECTION 

TRACTS 


NUCLEI 

OF  THE 

MEDULLA  OBLONGATA 


GRAY  SUBSTANCE 

OF  THE 

SPINAL  CORD 


PRIMARY   PROJECTION 
TRACTS 


PERIPHERY. 


NERVE-CELLS.  35 

The  schematic  representation  of  nerve-tracts  thus  ex- 
hibited (if  extended  cephalad)  would  include,  according  to 
Spitzka,  the  thalamus  as  the  4th  category,  the  corpus  striatum 
as  the  5th  category,  and  the  cortex  of  the  cerebrum  as  the 
6th  category.  The  corpus  striatum  is  placed  above  the 
thalamus  because  certain  fibers  pass  through  the  latter  to 
reach  the  former. 

It  will  be  perceived  that  the  superior  member  of  the  system 
properly  embraces  the  fibers  of  the  cerebral  lobes — the  com- 
missural, radiating,  and  associating  systems  of  fibers  (Fig.  8). 
It  is  probable,  moreover,  that  the  gray  matter  of  the  cere- 
bellum (chiefly  that  of  the  cerebellar  cortex)  is  intimately  con- 
nected with  the  cortex  of  the  cerebrum  by  still  another  set  of 
fibers,  which  constitute  a  distinct  formation,  but  the  ramifi- 
cations of  which  can  not  be  so  described  in  this  general  intro- 
duction as  to  be  easily  comprehended  in  all  of  their  anatomical 
relations. 

It  may  be  asked,  *' Why  is  there  a  necessity  for  the  break- 
ing of  the  nerve-fibers  and  the  introduction  of  cell- elements  in 
the  course  of  a  tract  which  might  be  continuous?"  "  What  is 
the  object  of  so  disturbing  the  simplest  form  of  arrangement?" 
'*  What  is  the  function  of  the  nerve-cells  so  interposed?" 

It  is  not  possible,  with  our  present  knowledge,  to  answer 
all  of  these  inquiries  to  our  complete  satisfaction.  We  have, 
however,  sufficient  data  for  the  conclusion,  at  least,  that  these 
interruptions  in  the  course  of  nerve-fibers  are  not  solely  for 
the  purpose  of  effecting  a  simple  interchange  of  excitations 
between  different  groups  of  ganglion- cells,  placed  one  above 
the  other,  as  buckets  are  passed  up  and  down  a  ladder  from 
hand  to  hand  (using  an  illustration  borrowed  on  account  of 
its  aptness).  There  is  a  morphological  significance,  not  to  be 
overlooked,  in  these  interruptions,  which  can  often  be  demon- 
strated. These  interposed  cells  possess  the  power  of  deflecting 
the  current  passing  along  the  nerves  to  which  they  are  at- 
tached, as  the  switch  is  used  in  telegraphy  and  on  railroads. 
By  the  use  of  this  simple  device,  centripetal  and  centrifugal 
currents  may  be  allowed  to  pass  without  interruption  when 


36 


THE  BRAIN. 


necessity  demands  it ;  or,  again,  the  direction  of  the  current 
may  be  changed,  and  transmitted  (through  some  other  con- 
nection which  the  cell  possesses  by  means  of  libers  attached 
to  some  other  of  its  processes)  to  a  point  not  situated  upon 
the  direct  line  of  the  paths  of  the  projection  system. 


Fig.  13. — Diagrammatic  representation  of  the  fibers  in  the  cerebrum.     (Le  Bon.) 

We  have  reason,  also,  to  believe  that  each  nodal  mass  of 
gray  matter  has  an  automatism  of  its  own,  by  which  it  can 
influence  the  nerve- fibers  in  intimate  association  with  it  with- 
out the  intervention  of  the  larger  ganglia  above,  which  are  in 
some  instances  capable  of  controlling  it  when  necessary. 

GENERAL  ARRANGEMENT  OF  THE  FIBERS  OF  THE  PROJECTION  SYSTEMS. 

The  systems  of  nerve-fibers  found  in  the  cerebral  lobes 
have  already  been  discussed  at  some  length,  but  certain  addi- 
tional facts  pertaining  to  the   *' radiating  system"  (Fig. 


I 


;■  8)  a 


GENERAL  AERANQEMENT  OF  FIBERS.  37 

remain  untold.  Sections  of  the  cerebrum  are  of  aid  in  map- 
ping out  various  bundles  into  which  the  radiating  fibers  are 
grouped.  We  are  enabled  to  determine  with  ease  a  group 
connected  with  the  ''caudate  nucleus"  and  one  also  with  the 
"lenticular  nucleus"  of  each  hemisphere  (the  two  masses  of 
gray  matter  which  together  form  the  "corpus  striatum"); 
again,  one  connected  with  the  "optic  thalamus"  and  the  ad- 
jacent "corpus  quadrigeminum " ;  and,  finally,  a  bundle  of 
fibers  whose  course  differs  from  that  of  the  others— those  of 
the  "fornix."  The  latter  appear  to  connect  certain  regions  of 
the  cortex  with  the  anterior  tubercle  of  the  optic  thalamus, 
and  a  mass  of  gray  matter  at  the  base  of  the  brain,  called  the 
^^ mammillary  tubercle^'  or  "'corpus  candicans''^  (Fig.  11). 

It  is  now  believed  that  some  of  the  radiating  fibers  (those 
of  the  internal  and  external  capsule  of  the  cerebrum)  are  con- 
tinued directly  from  the  cortex  to  the  cms  without  the  inter- 
vention of  ganglion-cells.'  The  diagram  now  introduced  (Fig. 
14)  will  aid  in  following  these  details. 

In  the  second  member  of  the  projection  system — the  "  cms 
cerehrV — marked  alterations  maybe  observed,  in  regard  to 
the  number,  course,  and  arrangement  of  the  nerve-fibers,  from 
those  of  the  cerebrum. 

The  actual  number  of  fibers  seems  to  be  markedly  reduced 
by  passage  from  the  white  substance  of  the  cerebral  hemi- 
spheres through  the  substance  of  the  basal  ganglia.  The  fibers 
are,  moreover,  gathered  into  two  bundles  in  the  cms  ;  whereas, 
in  the  cerebrum,  they  form  several  bundles  before  the  inter- 
ruption of  these  ganglia. 

The  two  bundles  of  the  crus  have  been  named  by  Meynert 
the  "-basis  cruris^''  (the  "cmsta")  and  the  "tegmentum 
cruris^''''  from  their  relative  position  to  each  other  (Fig.  14). 
The  fibers  of  the  former  are  connected  chiefly  with  the  nuclei 
of  the  corpus  striatum  (as  can  be  seen  in  the  diagram),  which 
constitute  its  crown,  as  it  were.     Those  of  the  latter  (the  teg- 

'  The  latest  investigations  of  Fleehsig  seem  to  prove  conclusively  that  this  statement 
is  true  of  the  pyramidal  tracts.  He  locates  the  situation  of  these  fibers  in  the  middle 
third  of  the  internal  capsule,  slightly  posterior  to  its  knee. 


38 


THE  BRAIK 


men  turn  cruris)  are  connected  chiefly  with  the  optic  thalamus 
or  the  corpus  quadrigeminum. 

Physiologically,  the  basis  cruris  or  crusta  (Fig.  14)  may  be 
regarded  as  a  centrifugal  or  motor  tract,  and  the  tegmentum 
cruris  (Fig.  14)  as  a  centripetal  or  sensory  tract.  This  state- 
ment is  not  absolutely  correct,  but  it  is  practically  advisable 
to  so  regard  it.  * 


MEDULLA 

Fio.  14. — Diagram  of  the  course  of  sensory  and  motor  tracts  in  the  mesocephalon  and 

Iieniisphercs.     (Seguin.) 

S,  sensory  tract  in  posterior  region  of  mesocephalon,  extending  to  0  and  T,  occipital  and 
temporal  lobes  of  hemispheres ;  M,  motor  tract  in  basis  cruris,  extending  to  P  and 
F,  parietal  and  (part  of)  frontal  lobes  of  hemispheres ;  C.  Q.,  corpus  quadrigeminum ; 
0.  T.,  optic  thalamus ;  N.  L.,  nucleus  lenticularis ;  N.  C,  nucleus  caudatus ;  1,  the 
fibers  forming  the  "  tegmentum  cruris  "  (Meyncrt) ;  2,  the  fibers  forming  the  "  basis 
cruris"  (Mcynert). 


In  studying  the  brains  of  mammals,  these  two  bundles  of 
fibers  and  the  ganglia  connected  with  them  give  evidence  of 
an  independence  of  one  another  which  governs  the  develop- 
ment of  each.  Where  the  frontal  and  parietal  lobes  are  large, 
we  find  the  "basis  cruris"  and  the  two  nuclei  of  the  ''  corpus 
striatum "  (Figs.  8  and  14)  highly  developed  ;  on  the  other 
hand,  when  these  lobes  are  at  their  minimum  we  find  the 
'* tegmentum  cruris"  and  its  ganglia  developed  in  excess. 


PROJECTION-  TRACTS  OF  CEREBRUM. 


39 


There  is  also  physiological  evidence  to  sustain  the  opinion 
that  the  basal  ganglia  and  the  two  bundles  of  the  cms  are 
capable  in  themselves  of  executing,  in  response  to  excitation 
from  without,  all  varieties  of  movements  in  an  animal  deprived 
of  its  cerebral  lobes  (above  the  level  of  the  basal  ganglia)  with 
a  nicety  and  exactness  which  are  astonishing. 

The  " crus  cerebri"  suffers  a  diminution  in  the  fibers  of  its 
motor  bundle  (basis  cruris)  after  its  entrance  into  the  sub- 
stance of  the  pons  Varolii.  This  is  very  apparent  when  the 
large  size  of  the  tract,  before  its  entrance  into  the  pons,  is 
contrasted  with  the  small  anterior  pyramid  of  the  medulla 
oblongata,  which  is  its  direct  continuation  after  its  exit 
(Fig.  6).   The  explanation  of  this  fact  is  as  follows :  All  of  the 


Fig.  15. — A  diagram  of  the  brain  in  transverse  vertical  section.     (Dalton.) 

1,  crus  cerebri ;  2,  internal  capsule ;  3,  optic  thalamus ;  4,  caudate  nucleus  of  corpus 
striatum ;  C.  C,  corpus  callosum ;  L.  N.,  lenticular  nucleus  of  corpus  striatum ;  S, 
fissure  of  Sylvius;  Fo,  gyrus  fornicatus;  F',  first  frontal  convolution;  F",  second 
frontal  convolution;  F'",  third  frontal  convolution;  T',  first  temporal  convolution; 
T",  second  temporal  convolution;  T'",  third  temporal  convolution;  H,  gyrus  hip- 
pocampi. 

peduncular  fibers  of  the  cerebrum,  which  become  intermingled 
with  the  gray  matter  of  the  corpus  striatum  (the  caudate  and 
lenticular  nuclei),  and  which  escape  from  that  ganglion  as 
fibers  of  the  basis  cruris  (Figs.  6  and  14),  are  not  destined  to 
form  parts  of  the  projection  system. 


40 


THE  BRAIN. 


The  ganglion-cells  of  the  pons  Varolii  exercise,  in  the  case 
of  some  special  cerebral  fibers,'  the  switch-like  action  previ- 
ously referred  to,  and  deflect  the  impulses,  which  they  carry, 
to  the  opposite  hemisphere  of  the  cerebellum  ;  hence,  in  the 
pons,  quite  a  large  bundle  of  distinct  fibers  appear  to  leave 
the  direct  tract  of  the  basis  cruris  (Fig.  14)  and  pass  to  the 
cerebellum  (through  the  processus  e  cerehello  ad  pontem). 
We  have  come  to  learn  that  a  communication  between  the 
cerebral  cortex  and  that  ganglion  is  thus  established,  but  its 
physiological  function  is  not  yet  ascertained  with  scientific 
exactness.  This  fact,  in  addition  to  others  which  will  be 
brought  forward  later,  leads  to  the  conclusion  that  the  cere- 
bellum is,  in  some  imperfectly  understood  way,  brought  into  i 
direct  relation  with  the  motor  tract  of  the  projection  system 
of  the  cerebrum,  and  is  endowed  with  some  power  either  of  i 
control  of  or  subtle  influence  over  motor  impulses.'  ^^j 

If  we  examine  cross-sections  of  the  ''pons  Varolii"  and  ] 
"crura,"  we  shall  perceive  that  the  pons  performs  for  the 
cerebellum  an  office  analogous  to  that  which  the  corpus  cal- 
losum  performs  for  the  cerebral  hemispheres — the  transmis- 
sion of  commissural  fibers  which  possibly  connect  homologous 
portions  of  the  two  lobes,  although  they  seem  to  become  united 
with  the  cells  of  the  gray  substance  of  the  pons.  We  may  | 
note,  furthermore,  that  these  commissural  fibers  of  the  pons  j 
subdivide  the  fibers  of  the  basis  cruris  and  tegmentum  cruris  j 
into  smaller  bundles  or  fasciculi.  In  addition,  nodal  masses  ! 
of  gray  matter  may  be  detected  in  both  the  crus  and  pons.      ^\ 

It  is  reasonable,  therefore,  to  conclude  that  the  cells  of     j 
these  nodal  masses  of  gray  substance  establish  some  form  of^jj 

*  These  fibers  are  chiefly  grouped  during  their  passage  through  the  lower  part  of  the  i 

cerebral  hemisphere  within  the  anterior  half  of  the  internal  capsule.     The  fibers  which  j 

arise  from  the  cerebral  cortex  and  apparently  terminate  in  the  gray  matter  of  the  pons,  j 

seem  to  spring  in  part  from  the  frontal  lobe  and  in  part  from  the  parietal  and  tempore-  I 

sphenoidal  lobes.     The  frontal  fibers  pass  through  the  anterior  half  of  the  internal  , 

capsule,  and,  after  their  escape  from  the  cerebrum,  occupy  the  inner  one  third  of  the  | 

basis  cruris.     The  fibers  from  the  parietal  and  temporo-sphenoidal  lobes  pass  through  j 
the  posterior  half  of  the  internal  capsule,  and  occupy  (after  their  escape  from  the  cere-_ 
brum)  the  (yuter  one  third  of  the  basis  cruris. 

'  This  subject  will  be  discussed  in  connection  with  the  architecture  of  the  cerebelli 


m 

ibellumflBl 

J 


PUOJEGTION  TRACTS  OF  CEREBRUM.  41 

communication  between  the  fibers  of  the  cerebral  projection 
tracts  and  the  commissural  fibers  of  the  cerebellum,  indepen- 
dent of  the  fibers  of  the  basis  cruris  which  appear  to  deflect 
themselves  from  the  path  of  the  projection  system  into  its 
substance. 

The  cerebellum,  furthermore,  has  undoubted  association 
with  special  fibers  of  the  cerebrum  (which  are  prolonged,  sub- 
sequently, into  the  basis  and  tegmentum  cruris)  by  means  of 
two  of  its  prolongations,  viz.,  the  processus  e  cerebello  ad 
testes  and  the  valve  of  Vieussens.  The  multiplicity  of  connec- 
tions which  this  ganglion  has  with  fibers  of  the  projection  sys- 
tem leaves  its  probable  functions  a  matter  of  speculation.  The 
theories  advanced  will  merit  consideration  later  in  the  course. 

Finally,  the  ganglia  of  the  brain  have  intimate  relation 
with  certain  nerve-tracts  which  are  independent  of  the  projec- 
tion system  proper — viz.,  the  fibers  of  special  cranial  nerves, 
which  are  more  or  less  independent  of  the  tubular  gray 
matter. 

The  olfactory,  optic,  and  auditory  apparatuses  must  be 
considered,  therefore,  as  modified  types  of  projection  systems, 
which  bear,  however,  striking  analogies  to  the  projection  sys- 
tem extending  to  nerves  of  spinal  origin,  although  possessing 
peculiarities  of  structure  essentially  their  own  (Fig.  12).  In 
these  modifications  of  the  general  arrangement,  the  middle 
projection  fibers  appear,  at  a  first  glance,  to  be  wanting,  as 
there  is  with  some  cranial  nerves,  as  far  as  we  at  present 
know,  no  organ  which  corresponds  exactly  with  the  central 
gray  tube  of  Meynert's  projection  system.  Many  observers, 
*  however,  incline  to  the  view  that  the  peripheral  ganglion- cells 
are  analogous  to  the  tubular  gray  matter.  These  consider, 
for  example,  the  fibers  of  the  optic  tract  as  a  middle  system 
of  projection,  and  the  radiating  fibers  in  the  retina  as  the 
external  system  of  projection. 

The  projection  tracts  of  the  cms  are  prolonged  into  the 
medulla  oblongata  and  spinal  cord  (Fig.  8),  where  they  be- 
come more  or  less  intimately  associated  with  the  tubular  gray 
matter. 


42 


TEE  BRAIN. 


The  third  member  of  the  projection  system  exhibits  an 
augmentation  in  the  actual  number  of  fibers  over  those  found 
in  the  crus ;  as  there  can  be  no  doubt  that  the  total  number  of 
fibers  in  the  spinal  nerves  exceed  greatly  those  comprised  in 
the  basis  and  tegmentum  cruris.  Here,  again,  vre  have  undis- 
pu table  evidence  that  the  gray  matter  of  the  spinal  cord,  by 
means  of  its  cell  elements,  serves  as  a  means  of  conduction  of 
nerve  impulses,  and  also  as  a  point  of  origin  for  additional 
nerves,  whenever  demanded. 

The  motor  tracts  of  the  basis  cruris  become  joined  to  cells 
in  the  gray  matter  of  the  spinal  cord,  which  are  connected 
with  the  anterior  or  motor  roots  of  the  spinal  nerves  (see 
Fig.  8).  The  fibers  of  the  tegmentum  cruris  unite  with  simi- 
lar cells  which  lie  more  posteriorly,  and  are  associated  with 
the  posterior  or  sensory  roots  of  the  cranial  and  spinal  nerves 
(see  Fig.  8).  The  individual  course  of  the  various  bundles 
(that  help  to  form  the  motor  and  sensory  tracts  of  the  crus 
cerebri)  through  the  medulla  and  spinal  cord  will  be  described 
in  subsequent  pages. 

It  may  be  well,  however,  to  state  in  general  terms  that 
each  separate  nerve-fiber  which  properly  belongs  to  the  pro- 
jection tracts  of  the  crus  finds  its  course  interrupted  by  the 
interpolation  of  a  ganglion-cell  before  it  reaches  the  particu- 
lar spinal  nerve,  with  the  action  of  which  it  is  to  become  inti- 
mately associated.  The  nerve-cells  of  the  spinal  cord  help  to 
explain  the  various  phenomena  which  are  comprised  under 
the  head  of  spinal  automatism ;  since,  in  the  beheaded  animal, 
no  other  source  of  reflex  motor  action  can  be  discovered,  al- 
though its  existence  has  been  demonstrated  beyond  a  doubt, 
both  in  animals  (Pfluger)  and  even  in  man  (Robin).  By  the 
interpolation  of  nerve-cells  in  the  course  of  nerve-fibers,  sen^K 
sory  impressions  may  be  carried  to  any  one  of  the  three  main  ^ 
divisions  of  gray  matter,  and  there  excite  a  response  in  the 
form  of  a  motor  impulse,  viz.,  the  tubular  gray  suhstance 
and  its  expansions.,  the  basal  ganglia^  or  the  cortex  of  tJie^^  i 
cerebrum.  These  points  will  be  discussed  in  subsequent 
pages. 


THE  CORTICAL    GRAY  MATTER.  43 

THE   CEREBRAL   CORTEX. 

If  a  section  of  the  cerebral  cortex,  in  a  plane  vertical  to 
that  of  the  surface,  be  pressed  between  two  thin  plates  of 
glass  and  then  inspected  by  transmitted  light,  it  will  appear 
to  the  naked  eye  to  resolve  itself  into  secondary  zones,  or 
strata  of  unequal  transparency. 

It  is  this  peculiar  appearance  that  has  led  some  anatomists 
to  describe  the  cortex  as  consisting  of  regularly  stratified  lay- 
ers of  alternating  gray  and  white  matter — a  statement  which 
is  not  supported  by  microscopical  research. 

The  intimate  structure  of  the  cortical  substance  is  not  the 
same  in  all  parts  of  the  brain.  Many  valuable  suggestions 
are  afforded  by  the  variations  in  this  respect  which  special 
parts  present  from  the  type  most  commonly  met  with  in  the 
convolutions.     These  will  be  considered  later. 

The  convolutions  of  the  brain  apparently  obey  some  fixed 
law  as  regards  their  development,  distribution,  and  the  micro- 
scopical characteristics  of  their  cortical  layer. 

If  the  most  prominent  points  of  the  convolutions  in  any 
given  horizontal  or  vertical  section  of  the  adult  brain  be 
united  by  a  curved  line,  it  will  be  found  that  the  curiie  de- 
scribed is  continuous  if  the  brain  be  in  all  respects  a  typical 
one.  In  old  age,  effects  of  senescence  become  manifest  in  the 
brain,  as  in  the  other  organs.  One  of  these  is  a  retraction  or 
sinking  of  certain  convolutions,  so  that  a  continuous  curve  no 
longer  unites  the  tips  of  all  the  convolutions  over  which  it  is 
described.  In  addition,  the  gray  matter  of  the  cortex  be- 
comes diminished  in  thickness  in  old  age ;  and  its  color  is 
changed  to  a  yellowish  white,  on  account  of  a  transition  of 
the  cell  elements  into  a  granulo-fatty  state.  In  certain  men- 
tal diseases,  also,  which  tend  to  create  a  premature  dotage, 
such  as  alcoholic  poisoning,  paralytic  dementia,  melancholic 
delirium,  etc.,  we  are  apt  to  discover  an  atrophy  of  the  cor- 
tical layer. 

The  convolutions  of  the  brain  present  all  varieties  of  con- 
figuration, not  only  in  animals  of  different  species,  but  even  in 


u 


TEE  BRAm. 


the  same  individual.  Even  in  homologous  regions  of  the 
brain  the  convolutions  are  seldom,  if  ever,  the  same  in  point 
of  outline.  Luys  suggests  that  this  can  be  demonstrated  by 
laying  a  piece  of  transparent  paper  over  a  vertical  section 
of  the  brain,  and  tracing  upon  it  the  outline  of  the  convolu- 


Fio.  16. — Structure  of  the  convolutions.     (After  Baillarger.) 

1,  the  six  alternate  gray  and  white  layers  in  the  cortical  substance  of  the  convolutions ; 
2,  enlarged  section  of  a  convolution — the  left  half  is  seen  by  reflected  light — layers 
arranged  as  in  the  preceding  figure — in  the  right  half,  seen  by  transmitted  light,  the 
medullary  layers  are  rendered  dark  by  their  opacity — the  layers  of  gray  substance,  on 
the  other  hand,  which  are  translucent,  are  represented  in  white ;  3,  section  of  a  con- 
volution showing  the  unequal  thickness  of  the  white  layers — at  first  sight  only  three 
layers  can  be  distinguished,  two  gray  and  an  intervening  white  layer — more  attentive 
examination  shows  six  layers,  the  superficial  and  deep  white  layers  being,  however, 
very  narrow ;  4,  section  of  a  convolution  showing  the  three  layers  of  gray  matter 
observed  by  Vicq  d'Azyr  in  the  occipital  lobe ;  5,  tendency  to  radiation  shown  by 
the  white  fibers  in  the  gray  matter  of  the  convolutions;  6,  section  of  a  cerebral 
convolution  in  a  newly-born  infant,  seen  by  reflected  light— it  presents  a  homogene- 
ous appearance ;  7,  same  section  seen  by  transmitted  light — presents  the  same  strati- 
fication and  tendency  to  radiation  which  are  observed  in  the  adult. 


m 


tions  of  one  side  as  far  as  the  median  line ;  now  double  the 
paper  over  so  as  to  cover  corresponding  regions  of  the  oppo- 
site side,  and  no  two  convolutions  will  be  found  to  present 
an  absolutely  identical  contour.  The  same  observer  states 
that,  in  his  extended  researches,  he  has  never  encountered 
brain  which  was  perfectly  symmetrical  when  tested  in  this; 
way.    This  statement  has  a  medico-legal  value — asymmetry 


THE  CEREBRAL   CORTEX.  45 

having  been  thonght  by  some  neurologists  to  be  conclusive 
evidence  of  existing  disease  or  congenital  defect. 

The  color  of  the  cortex  differs  with  age  and  the  race.  In 
the  dark-skinned  races,  especially  marked  in  the  negro,  it  is 
darker  than  in  the  white  man  ;  in  the  babe,  it  is  uniformly 
grayish,  and  of  a  gelatinous  consistence  ;  in  early  childhood, 
it  assumes  a  somewhat  rosy  tint ;  in  the  adult,  its  vascularity 
is  apparent ;  in  old  age,  it  assumes  a  yellowish  white  color* 
and  loses  its  vascularity.  The  gray  color  of  some  zones  as 
compared  with  others  is  stated  by  Meynert  to  be  due  to  the 
presence  of  pigment  within  the  cell  elements  with  which  the 
cortex  is  so  abundantly  supplied.' 

The  tJiicJcness  of  the  cortical  substance  varies  in  different 
regions  of  the  brain,  being  thicker  in  the  anterior  parts,  as  a 
rule,  than  in  the  posterior.  Its  average  thickness  may  be 
stated  to  vary  from  two  to  three  millimetres.  Gratiolet  has 
called  attention  to  the  curious  fact  that  the  thickness  of  the 
cerebral  cortex  is  much  less  in  races  of  small  stature  than  in 
those  of  greater  average  height. 

If  we  make  thin  sections  of  the  cortex  and  color  them 
with  different  reagents  (each  of  which,  by  its  chemical  affini- 
ty, tends  to  bring  out  some  special  feature  in  its  anatomical 
construction),  and  then  subject  them  to  the  magnifying  power 
of  strong  objectives,  we  are  enabled  to  form  a  clearer  concep- 
tion of  the  actual  construction  of  the  zones  of  unequal  trans- 
parency seen  by  the  naked  eye  (first  brought  to  professional 
notice  by  Baillarger)  (Fig.  16).  By  the  judicious  employment 
of  gradually  increasing  powers  in  the  microscopic  objectives 
used,  the  general  arrangement  of  the  elements  may  be  first 
mastered,  and,  later  on,  the  minute  details  of  each  of  the  com- 
ponent parts  may  be  studied. 

In  such  research  we  are  struck,  at  first,  by  the  immense 
numbers  of  pyramidal- shaped  cells ""  which  are  encountered 

'  We  know  that  the  medullary  substance  of  the  "  island  of  Reil "  and  of  the  "  exter- 
nal capsule  "  is  here  and  there  studded  thickly  with  nerve-cells,  which,  however,  fail  to 
give  it  a  gray  appearance  on  account  of  the  absence  of  pigment. 

2  Meynert  pronounces  the  nerve-cells  of  the  outer  cortical  layer  to  be  distinctly  star- 
shaped,  but  others  disagree  with  him. 


46 


THE  BRAIN. 


within  the  cortical  substance,  each  of  which  seems  to  point 
toward  the  surface  of  the  brain ;  as  if  attracted  toward  it,  like 
needles  ''so  magnetized  as  to  always  point  to  the  pole.' 


Fig.  17. — Cortical  cell  of  the  deeper  zones  at  about  eight  hundred  diameters.     (Luys.) 

A  section  of  the  cell  is  made  through  its  greater  axis,  its  interior  texture  being  thus  laid 
bare.  A  represents  the  superior  prolongation  radiating  from  the  mass  of  the  nu- 
cleus itself ;  B,  lateral  and  posterior  prolongations ;  C,  spongy  areolar  substance, 
into  which  'the  structure  of  the  cell  itself  is  resolved ;  I),  the  nucleus  itself  seems 
only  to  be  a  thickening  of  this  areolar  stroma — it  sometimes  has  a  radiated  arrange- 
ment ;  E,  the  bright  nucleolus  is  itself  decomposable  into  secondary  filaments. 

These  are  the  nerve-cells.  They  are,  furthermore,  disposed  in 
regular  strata,  parallel  with  the  surface  of  the  convolutions, 
and  i)laced  successively  upon  each  other.  It  will  be  noticed, 
in  the  third  place,  that  the  cells  grow  larger  as  you  pass  from 
the  external  strata  inward ; '  and  that  those  of  each  individ- 
ual layer  have  some  distinctive  peculiarities  which  appear  to 
shed  some  light  upon  their  function.     AVhen  we  come  to 

*  They  vary  from  10  /*  to  40  /x  in  height. 


THE  CORTICAL    CELLS. 


47 


study  the  characteristics  of  the  different  layers,  these  points 
will  be  discussed.  Our  attention  is  drawn,  in  the  fourth 
place,  to  the  fact  that  these  cells  gim  off  hrancMng  processes 
which  anastomose  with  each  other,  thus  constituting  what 
may  be  considered  a  continuous  structure  over  the  whole  area 
of  the  convolutions.  By  means  of  these  small,  thread-like 
processes,  the  cells  are  probably  enabled  to  communicate 
vibratory  molecular  movements  from  one  to  the  other,  while 
some  are  the  unquestioned  means  also  of  communication  be- 
tween the  nerve- cells  and  the  nerve-fibers  which  we  have  pre- 
viously discussed.  In  the  fifth  place,  we  encounter  an  inter- 
cellular substance^  which  serves  to  cement  the  cells  and  to 
maintain  a  fixed  position  for  them,  as  well  as  to  furnish  pas- 
sage for  the  vessels  of  nutrition  of  the  cells.  This  is  the 
'"^neuroglia,"  a  connective-tissue  formation. 

We  are  now  enabled  to  appreciate  the  analogy  which  Mal- 
pighi  drew  between  the  arrangement  of  the  cells  of  the  cortex 
and  the  seeds  of  the  pomegranate,  imbedded  in  the  white 
fibrous  tissue  which  incloses  them  on  all  sides. 

The  nerne-fihers  probably  join  the  nerve-cells  in  the  region 
of  their  bases  ;  the  processes  given  off  from  the  apices  of  the 
cells  appear  to  serve  as  a  means  of  communication  between 
the  cells  of  the  different  layers  of  the  cortex. 

The  ner ve- cells ^  when  examined  as  individual  structures, 
are  found  to  present  a  bright  nucleus '  and  a  niicleolus,  and 
to  be  destitute  of  an  investing  membrane  (Luys).  In  fresh 
brains,  they  are  of  an  amber  color.  When  very  high  powers 
are  used,  the  protoplasm  of  the  nerve-cells  becomes  resolved 
into  distinct  fibrillse,  which  interlace  with  each  other  and 
become  agglomerated  in  the  region  of  the  nucleus.  The  ar- 
rangement of  these  delicate  fibrillse  has  been  compared  by  one 
of  the  most  recent  investigators  (Luys)  to  the  "wickerwork 
of  an  osier  basket,"  and  the  same  observer  claims  that  the 

*  In  young  subjects  and  in  normal  adult  brains,  the  nuclei  are  seldom  round  or  oval. 
They  are  usually  pyramidal  or  spi7idle- shaped,  running  out  into  sharp  ends.  Their  angles 
are  often  seen  to  project  into  the  cell-processes,  Arnold  states  that  the  pressure  of  the 
protoplasm  of  the  cell  tends  to  make  the  outline  of  the  nucleus  correspond  to  that  of  the 
cell. 


48  TEE  BR  Am. 

nucleus  and  nucleolus  have  been  resolved  by  him  into  dis- 
tinct secondary  filaments  which  present  a  radiated  appear- 
ance. I  quote  from  him  as  follows:  *' Imagination  is  con- 
founded when  we  penetrate  into  this  world  of  the  infinitely 
little,  where  we  find  the  same  infinite  divisions  of  matter  that 
so  vividly  impress  ns  in  the  study  of  the  sidereal  world  ;  and 
when  we  thus  behold  the  mysterious  details  of  the  organiza- 
tion of  an  anatomical  element,  which  only  reveal  themselves 
when  magnified  from  seven  to  eight  hundred  diameters,  and 
think  that  this  same  anatomical  element  repeats  itself  a 
thousand-fold  throughout  the  whole  thickness  of  the  cere- 
bral cortex,  we  can  not  help  being  seized  with  admiration ; 
especially  when  we  think  that  each  of  these  little  organs 
has  its  anatomy,  its  individuality,  its  minute  organic  sensi- 
bility ;  that  it  is  united  with  its  fellows ;  that  it  partici- 
pates in  the  common  life ;  and  that,  above  all,  it  is  a  silent 
and  indefatigable  worker,  discreetly  elaborating  those  nerv- 
ous forces  of  the  psychic  activity  which  are  incessantly  ex- 
pended in  all  directions  and  in  the  most  varied  manners, 
according  to  the  different  calls  which  are  made  upon  it  and 
set  it  vibrating." 

The  neuroglia^  to  which  we  have  referred  in  a  general  way 
as  serving  as  a  cement  to  fix  the  nerve-cells,  allows  also  of  the 
transmission  of  blood-vessels  into  the  substance  of  the  cortex. 
The  branches  given  off  from  the  vessels  of  the  pia  mater  enter 
the  cortex  upon  its  free  surface,  and  immediately  divide  into 
a  network  of  small  capillary  twigs,  which  invest  the  adjacent 
nerve-cells  in  an  areola  extremely  rich  in  blood-vessels.  In 
addition  to  these  two  functions,  the  most  superficial  layer  of 
the  cortex  is  composed  largely  of  this  connective-tissue  forma- 
tion, as  will  be  seen  by  studying  the  diagrammatic  drawing 
which  I  now  show  you. 

This  stratum  of  the  cortex  has  been  compared  by  Luys 
to  the  epithelial  covering  of  the  mucous  and  cutaneous  sur- 
faces of  the  body,  since  he  believes  that  it  is  designed  to 
protect  the  nerve-cells  from  direct  contact  with  the  capillaries 
of  the  pia  mater. 


GENERAL  STRUCTURE  OF  CORTEX. 


49 


Fig.  18. — Half  diagrammatic  figure  of  the  cerebral  cortex,  magnified  about  ttoo  hundred 
and  eighty  diameters,  giving  a  view  of  the  entire  arrangement  of  the  different  zones  of 
cells,  and  their  relatione  to  one  another,  and  to  the  surrounding  neuroglia.     (Luys.) 

The  region  A  corresponds  to  the  sub-meningeal  network  of  the  neuroglia.  The  region  B 
to  the  sub-meningeal  zones  of  small  cells  (region  of  the  sensorium  commune) ;  the 
region  C  is  intermediate  between  the  sub-meningeal  and  the  deeper  zones  of  cells 
which  are  indicated  at  D.  At  E  we  note  the  dipping  of  the  fasciculi  of  white  sub- 
stance into  the  plexus  of  cortical  cells.  F  represents  a  capillar}'  at  the  moment  when 
it  plunges  into  the  tissues  of  the  cortex. 


50  THE  BRAIK 

While  serving  thus  as  a  source  of  protection  and  isolation, 
it  probably  also  filters,  as  it  were,  the  juices  which  escape 
from  the  meningeal  vessels  for  the  nourishment  of  the  nervous 
elements.  This  view  seems  to  be  supported  by  a  peculiarity 
in  the  arrangement  of  the  smaller  vessels,  which  can  be  traced 
into  the  substance  of  the  cortex.  They  are  found  to  be  sur- 
rounded for  almost  their  entire  circumference  by  an  adventi- 
tious sheath,  which  "invests  them  like  a  muff,"  and  prevents 
the  nerve-cells  from  coming  into  direct  contact  with  any  por- 
tion of  the  vascular  system.  '  We  are  forced,  therefore,  to 
believe  that  the  nerve-cells  derive  their  nutritive  elements 
only  through  the  mediation  of  other  structures.  The  external 
layer  of  the  cortex  will  subsequently  be  considered  in  detail. 

We  are  prepared  now  to  take  up  the  special  types  of 
cortex  which  are  met  with  ;  and  to  study  the  hints  which  are 
thus  afforded  respecting  the  functions  of  various  parts.  By 
the  laws  of  analogy,  we  are  led  to  infer  that  parts  which  have 
a  similarity  of  construction,  and  in  which  the  cell-elements 
are  absolutely  identical,  probably  have  a  similarity  of  func- 
tion. If,  on  the  other  hand,  the  function  of  certain  regions 
has,  by  physiological  experiment,  been  clearly  made  out,  we 
are  led  to  study  closely  the  minute  structure  of  those  special 
regions,  with  the  hope  of  finding  other  localities  where  iden- 
tical formations  exist. 

The  superficial  layer  of  the  cortex  has  been  described  by 
Virchow  as  "the  neuroglia";  by  Kolliker  as  "connective 
tissue";  by  Deiters  as  "spongy  tissue";  by  Rokitansky  as 
"ependyma";  and  by  Wagner  and  Henle  as  "fused  gan- 
glion-cell substance."  Similar  tissue  found  in  the  olfactory 
lobes  and  Ammon's  horn  has  been  named  "gelatinous  sub- 
stance" by  Clarke,  and  "molecular  substance"  by  Kupfer. 
Hence,  we  must  be  prepared  to  meet  descriptions  of  this  layer 
under  the  above-mentioned  headings.  This  stratum  varies 
perceptibly  in  thickness  in  different  mammals,  and,  as  Mey- 
nert  expresses  it,  seems  to  be  overbalanced  and  thrown  in  the 
shade  by  the  deeper  nerve-cell  ladened  strata  in  the  nobler 
types  of  brains.     We  find  it  relatively  thin  in  the  brain  of 


SPECIAL   TYPES  OF  CORTEX.  51 

man  and  the  monkey,  thicker  in  the  dog  and  cat,  and  thickest 
(of  all  the  domestic  animals)  in  the  calf.  The  cells  found  in 
this  layer  are  chiefly  star-shaped  (Meynert)/  have  very  little 
protoplasm,  and  possess  many  finely  divided  processes.  These 
are  probably  non-nervous  in  function.  A  few  nerve-cells  are 
found,  however,  which  are  characterized  by  an  excess  of  pro- 
toplasm (Deiters)  and  forked  processes  ;  and  some  nerve-fibers 
may  be  also  detected  in  this  layer  (Arndt)  in  the  region  of  the 
surface,  which  interlace  in  all  directions.  In  the  ' '  gyrus  un- 
cinatus  "  this  medullary  layer  is  developed  to  a  high  degree. 

In  the  majority  of  the  convolutions  of  the  cerebrum  the 
cortex  may  be  subdivided  into  five  strata.  The  structural 
differences  in  the  four  strata,  underlying  the  one  already  con- 
sidered, consist  in  variations  (1)  in  the  relative  density  of 
distribution,  and  (2)  in  the  form  of  the  nerve-cells. 

As  regards  the  form,  that  of  the  pyramid  (the  only  one 
recognized  by  Arndt,  Luys,  Stephany,  and  others)  j^revails 
in  the  five-strata  type  of  cortex. 

In  the  second  stratum,  the  cell  elements  are  of  small  size 
and  closely  packed  together  ;  in  the  tMrd^  they  are  of  larger 
size,  gradually  increasing  both  in  size  and  distance  from  each 
other  as  you  pass  inward  from  the  more  superficial  portion 
(the  type  peculiarly  indicative  of  Ammon^s  horn) ;  in  the 
fourth,  Meynert  describes  closely  packed  cells  of  small  size 
(granule-like  formation) ;  in  i\\.Q  fifth,  the  same  author  claims 
to  detect  spindle-shaped  cells,"  which  he  considers  as  particu- 
larly characteristic  of  the  gray  matter  of  the  claustrum.  The 
fifth  layer  of  the  cerebral  cortex  is  subdivided  by  Lewis, 
Clarke,  and  Baillarger  into  two  layers,  thus  making  six 
layers.  Krause  has  added  a  seventh  layer,  which  he  de- 
scribes as  being  composed  of  very  small  cells  lying  upon  the 
white  substance  of  the  centrum  ovale.  These  cells,  according 
to  this  author,  may  be  pyramidal,  stellate,  or  fusiform. 

^  Deiters  recognizes  only  free  nuclei  in  this  layer.  They  measure  about  10  n  in 
diameter,  according  to  this  observer. 

2  The  spindle-shaped  cells  are  not  bipolar.  Processes  can  usually  be  detected  which 
spring  from  their  sides  as  well  as  from  their  extremities. 


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SPECIAL   TYPES  OF  CORTEX.  53 

Considerable  variety  occurs  in  different  parts  of  the  cere- 
bral cortex  in  regard  to  tlie  size  and  shape  of  the  nerve- cells, 
and  the  relative  thickness  of  the  layers. 

It  is  especially  worthy  of  notice  that,  in  those  regions  of 
the  cortex  which  have  lately  been  shown  to  contain  the  motor 
centers^  the  deeper  pyramidal  cells  have  been  found  by  Betz 
to  be  very  large,  and  arranged  in  clusters  or  nests  of  four  or 
five  cells,  which  are  more  or  less  defined.  These  are  often 
called  the  ''giant  cells ^  They  bear  a  strong  resemblance  to 
the  large  motor  cells  found  in  the  anterior  horns  of  the  gray 
matter  of  the  spinal  cord. 

Be  van  Lewis  and  Clarke  have  paid  special  attention  to  the 
situation  of  these  peculiar  cells,  and  have  arrived  at  the  con- 
clusion that  they  are  chiefly  found  among  the  small  cells  of 
the  fourth  layer  of  the  cortex.  The  same  observers  have 
applied  the  name  of  "ganglionic  cells ''^  to  these  peculiar 
elements,  which  apparently  have  an  intimate  relation  with 
the  function  of  muscular  movement,  and  have  designated  the 
layer  of  the  cortex  in  which  they  are  found  as  the  "ganglionic 
layer." 

In  the  neighborhood  of  the  calcarine  fissure  large  cells 
in  the  cortex  are  very  scanty,  their  place  being  occupied  by 
those  of  small  size.  In  some  parts  of  the  cortex  six  layers 
may  be  discovered ;  this  is  due,  as  shown  by  Bevan  Lewis, 
to  an  insertion  of  an  additional  layer  of  small  cells  between 
the  third  and  fourth  layers.  The  claustrum^  hippocampus 
major  or  cornu  Ammonis.,  and  the  olfactory  lobe  present 
especially  characteristic  variations  of  the  cortex  from  the 
more  common  five-strata  type  shown  in  the  diagram ;  but 
space  will  not  admit  of  a  minute  description  of  the  peculiari- 
ties of  each.'    It  may  be  stated,  however,  that  the  study  of 

'  The  researches  of  Bevan  Lewis  and  H,  Clarke  in  reference  to  the  minute  structure 
of  the  cerebral  cortex  in  man  and  animals  were  published  in  the  "  Proceedings  of  the 
Royal  Society"  in  1878.  The  former  author  has  also  contributed  articles  to  the  "Philo- 
sophical Transactions"  for  1880  and  1882.  Meynert's  valuable  article  is  to  be  found  in 
Strieker's  work  on  Histology. 

The  most  remarkable  deviations  from  the  normal  five-strata  type  of  cortex  are  to  be 
found  in  the  incurved  portion  of  the  cerebral  hemisphere  in  the  region  of  the  hippo- 
campus major  {cornu  Ammonis),  and  in  the  olfactory  lobe.     Henle  gives  cuts  showing 


54 


THE  BRAIN. 


the  cortical  elements  has  afforded  grounds  for  many  attractive     | 
theories  regarding  the  functions  of  special  regions  of  theH 
brain,  and  has  also  confirmed  an  opinion  (previously  formed 
by  research  in  embryology  and  comparative  anatomy)  that 
the  olfactory  lobes  and  tracts  are  component  parts  of  the     | 
brain,  and  are  not  to  be  classed  among  the  cranial  nervesj^j^?! 
Luys  has  contrasted  some  points  in  the  structure  of  the  olfac- 
tory bulbs  with  those  of  the  retinae ;  and  the  same  author     ' 
draws  a  strong  analogy  between  these  two  organs  of  special     j 
sense  and  abridged  projection  systems.  i^^j 

From  what  has  already  been  stated  in  regard  to  the  ana- 
tomical construction  of  the  cortex  of  the  cerebrum,  it  seems     1 
logical  to  assume  that  each  zone  may  he  thrown  into  a  state     \ 
of  nervous  activity  independently  of  the  others^  because  theiSej 
structure  of  the  cells  differs  in  the  various  strata.     On  the     ! 
other  hand,   the  connecting  processes  of  the  cell  elements     ^ 
which  unite  the  superimposed  strata  would  seem  to  indicate 
that  the  various  zones  of  the  cortex  may  he  associated  in     \ 
their  action  under  certain  conditions,  and  that  the  effects  of 
nervous  vibrations  within  the  cells  are  in  some  way  modified, 
according  to  the  nature  of  the  intermediate  cells  brought     \ 
into  play.  ^\ 

Nervous  actions,  like  vibratory  undulations,  are  probably  : 
transmitted  within  the  cortical  substance  both  horizontally,  j 
along  some  special  stratum,  and  vertically  from  the  super-  i 
ficial  to  the  deeper  cells,  or  vice  versa. 

It  is  worthy  of  notice  that  in  the  posterior  horns  of  the 
gray  matter  of  the  spinal  cord  we  find  cells  of  small  size     j 
which  are  analogous  in  many  respects  to  those  of  the  second     ; 
layer  of  the  cortex ;  while  in  the  anterior  horns  large  cells     j 
predominate  as  they  do  in  the  third  stratum.  .♦^  j 

Morphological  analogy  would  seem  to  indicate  identical  « 
function.  Luys  advances  the  theory  that  the  sub-meningeal  ; 
strata  which  are  characterized  by  the  presence  of  cells  of     ; 

excellent  sections  of  both  of  these  regions.  The  articles  referred  to  above  will  furnish*  i 
the  reader  with  a  complete  description  of  the  peculiarities  of  structure  which  are  char-  | 
acteristic  of  each. 


FUN-GTIONS  OF  CEREBRAL   CORTEX.  55 

small  size  are  to  be  considered  as  the  areas  of  diffusion  of 
general  and  special  sensations ;  and  that  the  deeper  strata, 
characterized  by  the  presence  of  large  cells,  are  the  centers 
for  the  development  and  emission  of  motor  impulses. 

There  is  certainly  some  ground  for  a  theory  that  the  jcor- 
tex  may  be  regarded,  from  a  physiological  standpoint,  as  an 
"extensive  instrument  possessing  a  sensory-motor  function"; 
analogous,  in  many  respects,  to  the  gray  matter  of  the  spinal 
cord,  but  endowed  with  special  attributes  of  a  higher  order 
(consciousness,  volition,  memory,  etc.). 

We  are  inevitably  forced  to  the  conclusion  that  the  cere- 
bral cortex  must  be  regarded  as  the  chief,  if  not  the  exclusive, 
seat  of  mental  actimty.  The  essential  proofs  of  the  psychical 
function  are  as  follows ; 

1.  In  the  animal  series,  the  cerebrum  seems  to  be  devel- 
oped in  excess  of  other  parts  of  the  brain  in  proportion  as 
the  individuals  of  any  class  approach  the  standard  of  man  in 
mental  powers.  We  judge  of  this  by  its  weight,  and  also  by 
the  number  of  "convolutions,"  or  "gyri."  The  latter  serve 
to  increase  the  amount  of  gray  matter  in  proportion  to  the 
superficial  area  of  the  brain. 

2.  In  cases  where  the  cerebrum  is  extremely  small  from 
birth,  there  appears  to  be  a  corresponding  diminution  in  the 
higher  mental  faculties,  or  idiocy  exists. 

3.  Some  forms. of  mental  disturbance  almost  always  follow 
injuries,  compression,  and  diseases  of  the  cerebrum — as  evi- 
denced by  insensibility,  somnolence,  abnormal  excitement,  or 
some  marked  eccentricities  of  demeanor. 

4.  Experimental  physiology  has  shown  that  a  removal  of 
the  cerebral  hemispheres  in  the  bird  (in  which  animal  it  is 
easily  accomplished)  produces  a  stupor  resembling  sleep,  in 
which  all  voluntary  acts  cease.  Flourens  noticed  that  a 
removal  of  the  cerebrum  in  thin  slices  tends  toward  a  gradual 
loss  of  mental  power.  Animals  so  mutilated  are  capable, 
however,  of  movements  of  a  reflex  character  when  any  of  the 
organs  of  sense  are  subjected  to  stimulation  ;  but  they  are  so 
regular  in  the  order  of  their  occurrence  that  they  may  be 


THE  BEAiy.  VH^^^^^I 

predicted,  thus  proving  that  they  are  not  the  result  of  voli- 
tion on  the  part  of  the  bird  itself.  Foster,  in  his  work  on 
physiology,  gives  an  interesting  and  concise  account  and 
summary  of  similar  experiments  made  upon  other  animals. 
Most  observers,  however,  have  arrived  at  about  the  same 
conclusions,  so  it  is  unnecessary  to  enter  into  detail  here  as 
to  the  results  of  the  experiments  made  by  each. 

Now,  from  what  has  been  already  stated  in  this  and  a 
previous  article,  we  can  construct  a  general  scheme  of  the 
nervous  system  as  follows :  r 

1.  The  central  gray  matter  of  the  spinal  cord.  This  has 
no  connection  with  the  higher  senses.  It  is  capable,  in  itself, 
of  the  simplest  kinds  of  reflex  acts,  by  means  of  the  spinal 
nerves.  These  can  be  produced,  at  the  will  of  the  experi- 
menter, in  the  beheaded  frog,  when  an  irritation  of  the  skin 
by  any  acid,  etc.,  is  created ;  and  Robin  has  satisfactorily 
performed  the  same  experiment  upon  a  beheaded  criminal. 
We  have  reason  to  believe  that  the  spinal  cord  can  be  slowly 
and  in  a  purely  automatic  way  taught  to  perform  certain 
series  of  muscular  movements  (as  in  playing  scales  upon  a 
musical  instrument,  for  example)  without  any  intervention  of 
the  higher  ganglia. 

2.  The  'basal  ganglia^  and  possibly  the  cerebellum.  These 
are  of  a  higher  order  in  point  of  construction  than  the  spinal 
gray  matter.  They  are  connected  directly  or  indirectly  with 
the  nerves  of  the  spinal  cord,  and,  in  addition,  with  those  of 
the  special  senses.  They  are  capable,  in  themselves,  of  exe-. 
cuting  more  complex  actions,  besides  those  of  a  purely  reflex 
type,  in  obedience  to  impressions  received  from  the  nerves  of 
special  sense,  as  well  as  from  the  spinal  nerves.  These  gan- 
glia are  probably  important  agents  in  guiding  muscular  move- 
ments in  response  to  visual  impressions  and  those  from  the 
sense  of  hearing.  In  this  way,  they  seem  to  have  an  impor- 
tant control  over  the  maintenance  of  equilibrium  (co-ordinated 
movement). 

3.  The  cerebral  cortex.  This  is  a  ganglion  of  the  highest 
order ;  in  which  the  mental  activities  are  seated,  in  addition 


TOPOGRAPHY  OF  CEREBRAL   CORTEX.  57 

to  the  function  of  elaborating  and  storing  of  sensory  impres- 
sions of  all  kinds,  and  transforming  them,  at  the  proper  time, 
into  approiDriate  motor  impulses.  Here  we  encounter  ''the 
mysterious  realms  where  the  living  forces  of  our  psychic 
activities  are  marshaled  and  organized ' ' ;  where  volition  has 
its  seat,  giving  to  the  physical  organization  its  individuality  ; 
and  "where  those  eternal  problems  respecting  the  relations 
of  our  corporeal  and  mental  being  are  solved  and  carried  into 
execution." 

TOPOGRAPHY   OF  THE  CEREBRAL  CORTEX. 

We  are  indebted  to  the  admirable  monograph  of  Ecker 
for  a  systematic  grouping  of  the  convolutions,  or  ''gyri," 
which  will  materially  assist  us  in  studying  the  peculiarities 
of  formation  of  each,  and  especially  in  defining  special 
centers  whose  functions  seem  to  have  been  determined  by 
experimental  physiology.  Many  of  the  terms  employed 
by  this  author  and  some  of  his  predecessors  are  now  em- 
bodied in  most  of  the  recent  works  on  physiology  and 
descriptive  anatomy,  although  there  are  structural  grounds 
(pointed  out  by  Meynert)  which  make  them  appear  some- 
what illogical. 

We  may  simplify  the  study  of  this  subject  by  first 
enumerating  four  lobes,  four  lobules,  and  eight  fissures, 
which  are  prominent  upon  the  exterior  surface  of  the  cere- 
brum.    These  are  as  follows  : 

r  The  frontal  lobe. 
rn  The  parietal  lobe. 

The  four  lobes  are:        ^   ^^^  temporo-sphenoidal  lobe. 


The  four  lobules  are : 


The  occipital  lobe. 

The  lobulus  centralis  (the  island  of  Reil). 

The  lobulus  paracentralis. 

The  lobulus  cuneus. 

The  lobulus  quadratus. 

Ascending  limb  of  the  fissure  of  Sylvius. 

Horizontal  limb  of  the  fissure  of  Sylvius. 

The  fissure  of  Rolando, 
m  i   The  external  parieto-occipital  fissure. 

The  eight  fissures  are  :  ^   The  transverse  fissure. 

The  hippocampal  or  dentate  fissure. 

The  calloso-marfiinal  fissure. 

The  calcarine  fissure. 


58 


THE  BRAIN. 


The  Principal  Fissures  of  the  Cerebrum. — By  referSi 
ence  to  Figs.  20  and  21,  the  following  points  of  interest  may  I 
be  noted  in  this  connection  :  j 

The  ascending  limb  of  the  fissure  of  Sylvius  {s")  passes  in  ; 
front  of  the  island  of  Reil  and  among  the  frontal  convolutions.     I 

The  Tiorizontal  limb  of  the  fissure  of  Sylvius  (s')  passes 
backward  behind  the  island  of  Reil,  and  separates  the  tem-     ; 
poro-sphenoidal  lobe  from  the  frontal  and  parietal  lobes,     \ 
which  lie  adjoining  it.  ' 

The  fissure  of  Sylvius  has  a  surgical  and  medical  impor- 
tance from  the  fact  that  it  contains  the  middle  cerebral  ! 
artery.  This  vessel  is  particularly  liable  to  obstruction  from  j 
the  impaction  of  an  embolus,  especially  upon  the  left  side  of  i 
the  body.  This  accident  is  commonly  followed  by  aphasia,  be-  ' 
cause  the  motor  centers  of  speech  are  supplied  by  this  artery,     i 

The  fissure  of  Sylvius  appears  at  about  the  fourth  month  \ 
of  foetal  life.  The  fissure  of  Rolando  appears  at  about  the  \ 
sixth  month,  and  is  determined,  according  to  the  investiga-  ; 
tions  of  Krause,  by  a  vein  that  joins  the  superior  longitudinal  i 
sinus  with  the  middle  cerebral  vein. 

The  fissure  of  Rolando  {c)  separates  the  frontal  from  the 
parietal  lobe ;    it  passes  downward  and  forward  from   the     j 
upper  part  of  the  cerebrum  till  it  almost  joins  the  horizontal     ; 
limb  of  the  Sylvian  fissure. 

The  external  parieto-occipital  fissure  (po)  separates  the 
parietal  and  occipital  lobes,  hence  its  name.  It  is  continued 
upon  the  inner  surface  of  the  cerebrum  as  the  ^'internal 
parieto-occipital  fissure."  It  is  very  variable  in  its  extent, 
and  is  sometimes  scarcely  recognizable. 

Among  the  minor  fissures  of  the  cerebrum  that  deserve 
mention  may  be  enumerated  the  transverse,  hippocampal, 
olfactory,  collateral,  calloso -marginal,  and  calcarine. 

The  transverse  fissure  (fissure  of  Bichat)  separates  the 
cerebrum  from  the  cerebellum  when  those  ganglia  are  in  their 
normal  relations  to  each  other.  It  is  continuous  with  the 
lateral  and  third  ventricles.  Here  the  pia  mater  enters  the 
ventricles  of  the  cerebrum. 


TOPOGRAPHY  OF  CEREBRAL   CORTEX. 


59 


The  Mppocampal  fissure  (dentate  fissure)  is  seen  upon  the 
internal  surface  of  the  cerebral  hemisphere,  and  indicates  the 
seat  of  a  convolution  in  the  descending  cornu  of  the  lateral 
ventricle,  known  as  the  ''hippocampus  major." 


Fig.  20. — Lateral  view  of  the  human  brain,  showing  its  lobes  and  fssures.    (After  Ferrier.) 

F,  frontal  lobe ;  P,  parietal  lobe ;  0,  occipital  lobe ;  T,  temporo-sphetioidal  lobe ;  S,  fis- 
sure of  Sylvius;  S',  horizontal  portion  ;  S",  ascending  portion  of  the  same;  c,  sulcus 
centralis  or  fissure  of  Rolando  ;  A,  anterior  central  convolution  or  ascending  frontal ; 
B,  posterior  central  convolution  or  ascending  parietal;  Fi,  superior;  Fa,  middle; 
F3,  inferior  frontal  convolution ;  f  1,  superior ;  fa,  inferior  frontal  sulcus ;  fa,  sulcus 
praecentralis ;  Pi,  superior  parietal  lobule,  or  postero-parietal  lobule ;  Pa,  inferior 
parietal  lobule,  viz. :  Pa,  gyrus  supra-marginalis ;  Pa',  gyrus  angularis ;  p,  sulcus 
intra-parietalis ;  cm,  termination  of  the  calloso-marginal  fissure ;  Oj  first,  Oa  sec- 
ond, O3  third  occipital  convolutions ;  po,  parieto-occipital  fissure ;  o,  sulcus  occipi- 
talis transversus;  Oa,  sulcus  occipitalis  longitudinalis  inferior;  Ti  first,  Ta  second, 
T3  third  temporo-sphenoidal  convolutions;  ti  first,  ta  second  temporo-sphenoidal 
fissures. 


The  olfactory  fissure  lodges  the  olfactory  bulb.  It  is  seen 
on  the  basal  aspect  of  the  cerebral  hemisphere. 

The  collateral  fissure  is  seen  on  the  basal  aspect  of  the 
occipital  and  temporal  lobe,  ending  at  a  point  opposite  the 
hippocampal  fissure.     It  corresponds  to  the  seat  of  the  so- 


60 


THE  BRAIN. 


called  ''collateral  eminence"  in  the  descending  cornu  of  the 
lateral  ventricle.  *   9 

The  calloso-marginal  fissure  (Fig.  21 )  runs  parallel  with 
the  corpus  callosum.  It  joins  the  lissure  of  Rolando  at  its 
upper  extremity.  * 

The  calcarine  fissure  marks  the  projection  of  the  hippo- 
campus minor  (calcar  avis)  into  the  posterior  horn  of  the 
lateral  ventricle.  It  joins  the  internal  parieto-occipital  fissure 
(Fig.  21). 

The  Lobes  of  the  Cerebrum.— These  are  designated  by" 
the  bones  with  which  they  bear  relation ;  hence  their  names 
will  serve  to  indicate  in  a  general  way  their  situation  an^ 
extent. 

The  main  sulci,  or  fissures,  are  the  dividing  lines  between 
the  lobes ;  the  smaller  sulci  seen  in  the  diagram  (Fig.  20) 
separate  the  different  convolutions,  or  ''gyri." 

Upon  the  internal  surface  of  the  cerebrum,  hidden  from 
view  by  the  contact  of  the  hemispheres  unless  they  be  pulled 
apart,  are  three  fissures,  which  have  been  designated  as  the 
^' calloso-marginal,'^''  the  ^'internal  parieto-occipital,'^^  and 
the  ''calcarine^  These  will  be  seen  in  the  cut  now  indi- 
cated (see  Fig.  21).  *^ 

The  FRONTAL  lobe  (F  in  Fig.  20)  is  contained  within  the 
anterior  fossa  of  the  skull.  The  frontal  lobe  of  the  human 
adult  brain  includes  nearly  the  anterior  half  of  the  cerebral 
hemisphere.  Only  that  portion  that  lies  in  front  of  the  as- 
cending frontal  convolution  is  contained  within  the  anterior 
fossa  of  the  cranium.  This  part  has  been  named  the  "pre- 
frontal lobe"  by  some  physiologists.  The  frontal  lobe  pre- 
sents four  "gyri,"  which  are  specially  named.  These  are 
shown  in  Fig.  20  to  be  as  follows : 

The  ascending  frontal  convolution,  or  gyrus  (A),  which 
lies  anterior  to  the  fissure  of  Rolando,  being  separated  from 
the  ascending  parietal  convolution  by  that  fissure. 

The  superior  frontal  convolution,  or  gyrus  (FJ,  whicl| 
joins  the  ascending  gyrus,  passing  horizontally  across  th€i:^ 
frontal  lobe. 


TEE   CEEEBRAL   CONVOLUTIONS, 


61 


The  middle  frontal  convolution^  or  gyrus  (F,),  passing 
parallel  to  the  superior. 

The  inferior  frontal  conmlution^  or  gyrus  (Fg),  lying  be- 
low the  middle,  embracing  the  ascending  limb  of  the  fissure 
of  Sylvius. 

Benedikt  has  observed  the  frequent  occurrence  of  2i  fourth 
frontal  convolution  in  the  brains  of  criminals.  It  was  found 
to  exist,  more  or  less  completely  developed,  in  the  majority 
of  brains  of  this  class  to  which  he  had  obtained  access.  It 
originated  usually  by  a  bifurcation  of  the  middle  frontal  con- 


FiG.  21. — A  diagram  of  the  cerebrum  in  longitudinal  median  section.    (After  Dalton.) 

1,  calloso-marginal  fissure ;  2,  parieto-occipital  fissure ;  3,  calcarine  fissure ;  A,  third  ven- 
tricle ;  B,  fifth  ventricle ;  D,  anterior  crura  of  fornix ;  C,  cuneus  (occipital  lobule) ; 
Q,  prsecuneus  (lobulus  quadratus) ;  P,  para-central  lobe ;  C  C,  corpus  callosum ; 
F,  gyrus  fornicatus. 

volution,  occasionally  by  a  bifurcation  of  the  superior  frontal 
convolution.  Other  points  of  interest  are  presented,  includ- 
ing the  occurrence  of  a  fifth  convolution.  These  facts  the 
author  regards  as  the  expression  of  a  great  pathological  law, 
that  atypical  structure  is  the  chief  agent  in  the  production  of 
atypical  (morbid)  performance  of  function. 

The  PARIETAL  LOBE  (P)  has  also  four  convolutions,  or  gyri, 
called  the  ascending,  the  supra-marginal,  the  parietal  lobule, 
and  the  angular  gyrus.  The  parietal  lobe  is  slightly  over- 
lapped by  the  occipital  bone,  so  that  it  does  not  correspond 
exactly  to  the  parietal  area  of  the  skull.    Its  convolutions  are 


m: 


THE  BRAIK 

not  as  clearly  defined  as  are  those  of  the  frontal  and  temporal 
lobes. 

The  ascending  parietal  convolution  (B  in  Fig.  20)  lies  back 
of  the  fissure  of  Rolando,  being  separated  from  the  ascending 
frontal  convolution  by  means  of  that  fissure.  :   ;= 

The  parietal  lohule  (P,),  the  supra-marginal  convolution  \ 
(Pg),  and  the  angular  gyrus  (P/),  being  the  other  three  con-  ! 
volutions  of  the  parietal  lobe,  are  situated  behind  the  ascend-  I 
ing  parietal  convolution. 

The  supra-marginal  convolution  is  named  from  its  rela-  ] 
tion  to  the  fissure  of  Sylvius.  It  lies  above  the  horizontal  | 
limb  of  that  fissure,  and  embraces  its  terminal  extremity.  \ 
The  inferior  parietal  lobule  lies  between  the  supra-marginal  | 
gyrus  and  the  so-called  intra-parietal  fissure.  This  fissure  j^\ 
separates  it  from  the  superior  parietal  lohule^  which  lies  ad- "  /  i 
jacent  to  the  longitudinal  fissure.  .:: 

The  convolutions  of  the  parietal  lobe  are  connected  to  cer-  ^!> 
tain  adjacent  convolutions  by  so-called  ''  annectant  gyri^  \ 
Thus,  the  superior  parietal  convolution  is  joined  to  the  occipi-  j 
tal  lobe  by  the  first  annectant  convolution,  and  the  angular 
gyrus  is  connected  to  the  occipital  lobe  by  two  or  three  an-  ; 
nectant  bands.  ;^;) 

The  TEMPORo -SPHENOIDAL  LOBE  (T  in  Fig.  20)  presents  , 
three  well-marked  convolutions,  which  run  in  an  antero-pos-  ; 
terior  direction.     They  are  named  as  follows :  -^\ 

The  superior  temporo-splienoidal  convolution  (T,),  which  j 
lies  below  the  horizontal  limb  of  the  Sylvian  fissure,  and  j 
which  is  continuous  behind  with  the  parietal  lobe.  ' 

The  middle  temporo- sphenoidal  convolution  (T,),  which  ! 
becomes  continuous  with  the  angular  gyrus,  and  is  connected  ^  \ 
to  the  middle  occipital  convolution.  '  i 

The  inferior  temporo-splienoidal  convolution  (T,),  seen  on      ' 
the  under  surface  of  the  cerebrum,  and  connected  with  the 
third  occipital  convolution.  I 

The  superior  temporal  convolution  (T^)  is  often  called  ] 
the  inframarginal  gyrus.  The  term  subicular  region,  or  ; 
the  region  of  the  subiculum  cornu  ammonis  (sigmoid  convo-      ! 


CEREBRAL   CONVOLUTIONS. 


63 


Intion  of  the  horn),  is  applied  to  the  tip  of  the  tempore- sphe- 
noidal lobe. 

The  OCCIPITAL  LOBE  (0  in  Fig.  20)  presents  three  badly  de- 
fined convolutions,  which  are  superimposed  upon  one  anoth- 
er, and  which  lie  in  a  more  or  less  antero-posterior  direction. 

The  superior  occipital  convolution  (O,)  is  connected  with 
the  parietal  lobule. 


Fig.  22. — A  diagrammatic  figure,  showing  tlie  cerebral  convolutions.     (Dalton.) 

S,  fissure  of  Sylvius,  with  its  two  branches,  a  and  6,  h,  h  ;  R,  fissure  of  Rolando-;  P, 
parieto-occipital  fissure;  1,  1,  1,  the  first  or  superior  frontal  convolution;  2,  2,  2,  2, 
the  second  or  middle  frontal  convolution  ;  3,  3,  3,  the  third  frontal  convolution,  curv- 
ing around  the  ascending  limb  of  the  fissure  of  Sylvius  {motor  center  of  speech) ; 
4,  4,  4,  ascending  frontal  (anterior  central)  convolution ;  5,  5,  5,  ascending  parietal 
(posterior  central)  convolution ;  6,  6,  6,  supra-Sylvian  convolution  (parietal  lobule), 
which  is  continuous  with  1, 1,  7,  the  first  or  superior  temporal  convolution;  8,  8,  8, 
the  angular  convolution  (or  gyrus),  which  becomes  continuous  with  9,  9,  9,  the  middle 
temporal  convolution;  10,  the  third  or  inferior  temporal  convolution;  11,11,  the 
superior  parietal  convolution;  12,  12,  12,  the  superior,  middle,  and  inferior  occipital 
convolutions  (called  also  the  first,  second,  and  third).  It  is  to  be  remembered  that 
the  term  "  gyrus  "  is  synonymous  with  "  convolution,"  and  that  both  terms  are  often 
interchanged. 


The  middle  occipital  convolution  (O,)  is  connected  with  the 
angular  gyrus,  and  also  with  the  middle  temporo- sphenoidal 
convolution. 


64 


THE  BRAIK 


The  inferior  occipital  convolution  (O,)  is  connected  with 
the  inferior  temporo-sphenoidal  convolution. 

The  admirable  diagram  (Fig.  22)  to  which  I  now  call  your 
attention  shows  the  relative  position  of  the  gyri,  as  well  as 
their  extent,  configuration,  and  lines  of  continuation  into 
neighboring  convolutions.  While  it  is  more  schematic  than 
that  of  Ferrier,  it  is  better  adapted  for  the  purposes  of  in- 
struction. In  its  general  outline,  however,  it  resembles  the 
brain  of  the  monkey,  rather  than  of  man,  as  the  frontal  lobes 
are  small,  and  the  fissure  of  Rolando  somewhat  far  forward. 

The  LOBULES  of  the  cerebrum  (enumerated  on  a  preceding 
page)  demand  individual  mention.  One  of  them  (the  lobulus 
centralis)  lies  at  the  base  of  the  frontal  lobe  ;  the  other  three 
are  found  upon  the  internal  surface  of  the  cerebrum.  f- 

The  lohulus  centralis^  or  island  of  Reil  {insula\  lies 
deeply  situated  in  the  commencement  of  the  fissure  of  Syl- 


Fio.  2'^.— Orbital  surface  of  the  frmtal  lobe  and  Island  of  Reil.     (Turner.) 

The  Island  of  Reil  is  exposed  by  removal  of  the  tip  of  the  temporo-sphenoidal  lobe; 
T S.y  cut  edge  of  this  lobe ;  a.  p.  «.,  anterior  perforated  space ;  a.  s.  R.,  p.  s.  Ji.,  ante- 
rior and  posterior  limitinp;  sulci  of  the  island ;  op.,  operculum  ;  tr.  s.,  tri-radiate  sul- 
cus ;  i.  o.  c,  a.  o.  c,  and  p.  o.  c,  internal,  anterior,  and  posterior  orbital  convolutions ; 
olf.  s.,  end  of  olfactory  sulcus ;  off.  tr.,  olfactory  tract,  bifurcating  into  the  inner  and 
outer  roots ;  m,  middle  root,  or  tuber  olfactorium. 


LOBULES  OF  THE  CEREBRUM.  65 

vius.  It  can  be  made  visible  only  by  the  separation  of  the 
lips  of  that  fissure  or  the  lifting  of  the  operculum  (see  Fig. 
23);  hence  it  lies  in  intimate  relation  with  the  ''basal  gan- 
glia." It  is  a  triangular  eminence,  and  consists  of  fiYQ  or  six 
straight  convolutions  {gyri  operti),  which  radiate  outw-ard 
from  a  point  just  external  to  the  anterior  perforated  space. 
It  covers  the  lenticular  nucleus  of  the  corpus  striatum.  The 
drawing  to  which  I  now  call  attention  shows  the  appearance 
of  this  lobule  after  the  end  of  the  temporo- sphenoidal  lobe 
has  been  removed.  The  discovery  of  Broca  that  this  region 
contains  the  center  for  the  movements  necessary  to  articulate 
speech  (a  statement  which  clinical  experience  has  not  yet  been 
able  to  overthrow)  has  given  it  a  clinical  and  physiological 
importance  in  excess  of  other  convolutions. 

Marshall  has  called  attention  to  the  fact  that  the  island  of 
Reil  is  imperfectly  developed  in  idiots,  as  are  also  the  corpus 
striatum  and  the  flocculus.  In  some  cases  the  convolutions 
of  the  island  of  Reil  were  found  to  be  entirely  absent. 

The  paracentral  lobule  (P  in  Fig.  21)  is  found  on  the  in- 
ternal surface  of  the  cerebrum,  in  front  of  the  lobulus  cu- 
neus.  There  is  clinical  evidence  to  sustain  the  belief  that 
this  lobule  is  connected  with  the  motor  tract.  We  know, 
also,  that  disease  of  this  convolution  produces  a  secondary  de- 
generation of  nerve  fibers  which  can  be  traced  through  the 
cerebrum  along  the  motor  tract  and  into  the  motor  regions  of 
the  spinal  cord.  The  "  giant  cells  "  of  Betz  are  also  found  in 
its  cortical  layer. 

The  paracentral  lobule  lies  in  the  region  of  the  mesial  or 
upper  extremity  of  the  fissure  of  Rolando.  It  probably  pre- 
sides over  movements  of  the  big  toe  (Horsley). 

The  lobulus  quadratus  (Q)  lies  between  the  paracentral 
lobule  and  the  lobulus  cuneus,  as  shown  in  this  drawing  (Fig. 
21).  It  is  bounded  by  the  internal  pane  to- occipital  and  the 
calloso-marginal  fissures. 

The  lobulus  cuneus  (C)  lies  posteriorly  to  the  lobulus 
quadratus.  Like  the  preceding  lobule,  it  is  inclosed  between 
two  fissures,  the  internal  parieto-occipital  and  the  calcarine. 


GCy  THE  BRAIN. 


^ 


The  calcarine  fissure  corresponds  in  position  to  ttie  seat 
of  the  so-called  hippocampus  minor  (calcar  avis),  on  the  floor 
of  the  posterior  cornu  of  the  lateral  ventricle.  ^m 

The  marginal  convolution  (gyrus  fornicatas)  follows  the 
curve  of  the  corpus  callosum  to  a  point  opposite  its  free  pos- 
terior border,  v^here  it  terminates  in  the  hippocampal  convo- 
lution. Meynert  believes  that  its  anterior  extremity  can  be 
traced  to  the  olfactory  sulcus. 

The  hippocampal  convolution  (superior  parie to- occipital 
gyrus  or  uncinate  gyrus)  is  formed  by  the  union  of  the  mar- 
ginal convolution  (gyrus  fomicatus)  and  the  occipito-temporal 
convolutions  of  the  internal  aspect  of  the  hemisphere.  It  can 
be  traced  to  the  tip  of  the  temporo-sphenoidal  lobe,  where  it 
ends  in  a  hook-like  bend,  called  the  ''uncus." 

The  so-called  dentate  convolution  (fascia  dentata)  begins 
at  the  posterior  extremity  of  the  corpus  callosum  and  ends  at 
the  uncus. 

Peduncular  Fibers  of  the  Cerebrum. — By  means  of 
the  ''peduncular"  or  "radiating  fibers"  of  the  cerebrum 
(Fig.  8),  the  cortex  is  enabled  to  receive  impressions  of  the 
external  world  and  to  transmit  motor  impulses  to  the  mus- 
cles. The  larger  part  of  these  fibers  (as  stated  in  a  previous 
article)  are  capable  of  being  traced  into  the  cms  and  spinal 
cord,  but  it  must  be  remembered  that  some  also  are  inti- 
mately connected  with  the  cranial  nerves,  especially  those 
associated  with  the  special  senses  of  smell,  sight,  and  audi- 
tion. It  may  not  be  considered  a  repetition  of  previous  mat- 
ter to  introduce  at  this  time  another  diagram,  which  will  make 
some  additions  to  the  facts  already  recorded. 

Many  points  shown  in  this  diagram  are  already  familiar 
to  you,  but  a  few  remain  which  deserve  mention.  One  bundle, 
the  "  stria  cornea,"  is  shown  in  the  drawing.  These  fibers  run 
from  the  cortex  of  the  temporal  lobe  of  the  cerebrum  to  the 
caudate  nucleus  of  the  corpus  striatum,  and  appear  on  the 
floor  of  the  lateral  ventricle  as  a  curved  band,  the  "tsenia 
semicircularis."  The  optic  thalamus  is  shown  to  receive  fibers 
which  spring  from  the  frontal  lobe,  passing  between  the  cau- 


PEDUNCULAR  FIBERS  OF  CEREBRUM. 


67 


date  and  lenticular  nuclei  of  the  corpus  striatum,  and  desig- 
nated in  the  diagram  as  (a) ;  also  fibers  from  the  temporal 
lobe,  the  walls  of  the  fissure  of  Sylvius,  the  gyrus  fornicatus, 
and  the  optic  tracts.     The  so-called  "geniculate  bodies  "are 


en 


€fCS\ 


(Cerebral 
Xpcdimclc- 


Fig.  24. — A  diagram  of  the  fibers  of  a  lateral  half  of  the  cerebrum.     (Foster's 
"Physiology."     Reichart's  edition.) 

CCff,  cortex  of  the  cerebral  hemisphere,  the  convolutions  of  which  are  seen  to  be  con- 
nected by  arcuate  connecting  fibers ;  C6,  cortex  of  cerebellum  ;  CR,  corona  radiata, 
consisting  of  fibers  extending  from  the  cortex  cerebri  to  LN  and  CiV,  the  *'  lenticu- 
lar" and  "caudate"  nuclei  of  the  corpus  striatum,  and  to  OT,  the  optic  thalamus. 
The  posterior  extremity  of  the  optic  thalamus  presents  two  enlargements,  the 
"  corpus  geniculatum  externum  "  and  "  internum,"  which  are  seen  to  be  connected 
with  the  optic  tracts.  The  letters  Op.  Tr.  are  placed  on  a  band  of  fibers  that  are 
believed  to  run  directly  from  the  cortex  cerebri  to  the  cortex  cerebelli.  SC,  "  stria 
cornea,"  or  "  taenia  semicircularis  "  ;  iSiV,  "  red  nucleus  of  the  tegmentum  " ;  JV, 
"  nates  "  ;  T',  "  testis  "  ;  P,  "  pineal  gland  " ;  6,  fibers  passing  directly  into  the  teg- 
mentum from  the  cortex  cerebri ;  Pa  (7,  the  band  of  fibers  to  the  right  of  these  let- 
ters are  part  of  the  "  superior  peduncle  of  the  cerebellum."  The  olfactory  nerve 
(o),  the  optic  nerve  {Op.  Tr.),  and  the  trigeminus  or  fifth  nerve  are  also  shown  to 
possess  an  intimate  connection  with  the  basal  ganglia  and  probably  with  the  cortex 
cerebri.  A  special  band  of  fibers  (Op.  7V.)  are  supposed  to  run  from  the  cortex 
cerebri  to  the  cerebellum. 

also  shown  to  be  connected  with  certain  bundles  of  radiat- 
ing fibers.  The  bundles  which  compose  the  "crusta"  and 
*' tegmentum  cruris"  are  made  more  apparent  than  in  the 
diagram  previously  drawn.  Finally,  the  fibers  connecting 
the  cortex  of  the  cerebellum  with  the  testis  are  clearly 
depicted. 


FUNCTIONS  OF  THE  CORTEX  OF  THE   CEREBRUM:. 

At  the  present  day  we  are  in  i^ossession  of  a  sufficient 
number  of  facts,  derived  from  clinical  observation,  patho- 
logical research,  and  experimental  investigation,  to  render  it     ,-\ 
certain  that  no  intelligence  can  exist  vrithout  brain  substance ;      2 
that  the  destruction  of  brain  substance  impairs  intellectual       j 
power  ;  and  that  the  normal  use  of  the  brain  implies  a  degen- 
eration of  its  substance  and  a  constant  process  of  regenera-       '■ 
tion,  as  exists  in  all  tissues.  '  ij 

It  was  formerly  supposed  that  the  cerebrum  was  destitute  j 
of  both  sensation  and  irritability,  since  experiments  seemed  to  ! 
show  that  no  pain  was  experienced  by  removal  of  portions  of  ] 
the  hemispheres,  nor  convulsive  movements  produced  by  direct  ~j^] 
stimulation  of  either  the  white  or  gray  matter.  It  has  there-  ''^^ 
fore  been  claimed  that  the  hemispheres  could  be  called  into  1 
action  only  in  response  to  a  sensory  impression  transmitted  to  ,  ! 
its  cells  through  sensory  nerves,  and  that  it  was  incapable  of  '"h  \ 
transmitting  or  appreciating  artificial  forms  of  stimulation.  ; 
In  1870,  however,  Fritsch '  and  Hitzig '  discovered  that  certain 
parts  of  the  gray  matter  of  the  hemispheres  of  the  brain  of  a 
dog  responded  to  a  weak  galvanic  current,  and  these  investi-  ■ 
gators  were  thus  enabled  to  locate  centers  where  certain  well-  H- 
defined  movements  could  be  produced  at  will.  These  experi-  gft^ 
menters  found  (1)  that  the  centers,  of  motion  were  always 
confined  to  the  anterior  parts  of  the  hemisphere ;  (2),  that  ' 
the  action  on  muscles  was  a  crossed  action,'  i.  e.,  on  the  side  \ 
opposite  to  the  stimulation ;  and  (3),  that,  after  severe  hsemor-  \ 
rhage,  the  excitability  of  the  gray  matter  disappeared,  thus 
possibly  accounting  for  the  negative  results  of  previous  ex-  | 
perimenters  in  the  same  line.  S| 

The  centers  of  motion  discovered  by  these  experiments      , 

'  Reichardt  u.  du  Bois-Raymond's  "  Archiv,"  18Y0.  JB|i 

*  Hitzig,  "Das  Gehirn,"  1874.  I 

3  Browji-Si^quard  has  shown  that,  in  exceptional  cases,  this  law  may  not  be  sustained        1 

by  clinical  facts.    "  Lancet,"  1876.    The  anatomical  researches  of  Flechsig,  however,  tend         I 

to  explain  the  exceptions  to  the  general  rule  (see  pages  of  this  volume  referring  to  the         ' 

"  pyramidal "  fibers  of  the  medulla  oblongata). 


J 


FUNCTION'S  OF  CEREBRAL   CORTEX.  69 

seemed  to  be  connected  with  parts  whicli  were  widely  sepa- 
rated, and  arranged  with  little  apparent  system  ;  thus  the 
muscles  of  the  neck  were  found  to  respond  to  galvanism  of  a 
center  in  the  middle  of  the  frontal  convolutions,  while  a  cen- 
ter adjoining  it  caused  a  response  in  the  extensor  and  abduc- 
tor muscles  of  the  fore-leg,  and  others  in  movements  of  the 
eye  and  face.  Ferrier'  has  of  late  repeated  and  confirmed 
many  of  the  results  obtained  by  the  experiments  of  these 
German  investigators.' 

The  effects  of  removal  of  the  cerebral  hemispheres  of  ani- 
mals have  been  studied  largely  upon  birds  and  the  monkey 
tribe,  and  with  results  which  are  comparatively  uniform. 
Without  entering  into  detail  as  to  all  the  effects  which  follow 
such  a  procedure,  in  case  the  basal  ganglia  are  left  intact,  the 
general  result  may  be  given  as  follows  :  The  animal  seems  to 
be  able  to  execute  all  the  movements  natural  to  it,  even  when 
complex  coordination  of  movement  is  required  ;  but  the  intel- 
ligence seems  to  be  impaired,  and  some  unusual  stimulus  must 
be  present  to  prompt  any  attempts  at  motion.  As  a  result  of 
this  conclusion,  the  mechanism  of  coordination  of  movement 
is  evidently  not  situated  in  the  cerebral  hemispheres. 

Flourens,"  from  a  series  of  experiments  made  in  1822  and 
1823,  concluded  that  the  removal  of  the  cerebrum  entailed  an 
entire  loss  of  will  power  and  also  of  the  perceptive  faculty, 
and  that  the  memory  was  utterly  destroyed.  Bouillaud,*  in 
1826,  differed  from  Flourens  as  regards  the  perceptive  fac- 
ulties, as  sight  and  hearing  were  shown  to  be  unaffected ; 
and  these  results  were  still  further  made  manifest  by  the  re- 
searches of  Longet,'  who  proved  also  that  taste  remained. 

A  careful  study  of  the  phenomena  which  accompany  cer- 
tain pathological  lesions  of  the  brain  in  the  human  subject, 

^  "West  Riding  Reports,"  1873;  "Functions  of  the  Brain,"  1876. 

^  A  large  number  of  distinct  centers  of  motion  are  mapped  out  by  this  author  on  a 
diagrammatic  chart.     The  reader  is  referred  to  Fig.  26  of  this  volume. 

^  "  Recherches  experimentales  sur  les  proprietes  et  les  fonctions  du  systemc  nerveux," 
Paris,  1842. 

*  "Recherches  experimentales  sir  les  fonctions  du  cerveau." 

^  "Anatomie  et  physiologic  du  s  stemc  nerveux,"  Paris,  1842. 


70  TEE  BRAIN. 

such  as  laceration  or  pressure  from  the  effusion  of  blood,  soft- 
ening of  the  cerebral  substance,  etc.,  if  taken  in  connection 
with  the  later  results  obtained  by  experiments  upon  living 
animals,  throws  considerable  light  upon  the  functions  of  cer- 
tain distinct  portions  of  the  encephalon. 

Softening  of  the  cerebral  Jiemispheres  and  the  degenera- ' 
tive  changes  which  often  follow  an  extravasation  of  blood 
into  their  substance  are  generally  indicated  by  alterations  in 
the  intellectual  condition  of  the  patient,  thus  confirming  the      ' 
physiological  experiments  upon  the  hemispheres.     Among      ; 
the  many  forms  in  which  this  impairment  of  intellect  may 
be  manifested  are  recognized  an  impairment  of  various  types      i 
of  memories ;  a  tardy,  inaccurate,  and  feeble  connection  of 
ideas  ;  an  irritability  of  temper,  with  a  childish  susceptibility 
to  petty  or  imaginary  annoyances  ;  easily  excited  emotional      | 
manifestations  ;  and  a  variety  of  phenomena  denoting  abnor-      \ 
mally  feeble  intellectual  power.  j 

Hugh  lings- Jackson '  has  shown  that  there  is  clear  evidence  £^| 
to  prove  that  disease  of  the  gray  matter  of  the  convolutions  I 
of  the  hemispheres  of 'the  cerebrum  may  not  only  produce 
delirium^  as  in  meningitis,  but  sometimes  convulsions^  either  j 
of  an  epileptiform  character  or  confined  to  particular  groups  ' 
of  muscles.  -.P,! 

Landois "  and  Hitzig "  both  announce  the  fact  that,  when  \ 
the  motor  areas  upon  the  convex  surface  of  the  cerebrum,  : 
which  control  the  movements  of  the  extremities,  are  excised,  j 
a  rise  in  the  temperature  of  the  corresponding  limbs  takes  ^^i 
place  and  lasts  for  some  months.  A  relationship  has,  more-^ 
over,  been  observed  between  the  brain  cortex  and  the  beat  of  j 
the  heart  (Balogh  *) ;  an  alteration  in  the  arterial  pressure  ! 
(Bochefontaine ') ;  contraction  of  the  bladder,  spleen,  and^! 
uterus ;  an  increase  in  the  flow  of  the  saliva ;  and  a  dilating  i 
effect  upon  the  pupil.  The  exact  localization  of  some  of  these  \ 
latter  centers  can  not,  as  yet,  be  considered  as  positive.  \ 

»  "London  Hosp.  Reports,"  1864;  "Clin,  and  Phys.  Researches,"  18Y3. 

•  Virchow's  "  Archiv,"  1876.  »  As  quoted  by  Foster. 

*  Hofmann  und  Schwalbe's  "  Bericht,"  1876.         »  "  Archives  de  Physiol.,"  1876. 


MOTOR  SPEECH  CENTER.  71 

Stimulation  of  the  cerebral  surface  has  been  observed  to 
result  in  a  well-marked  hcBmorrJiage  of  the  lungs  by  IN'oth- 
nagel. ' 

Most  authors  recognize  to-day  the  existence  of  a  ''msuaV^ 
center;  an  "auditory'^''  center;  a  " tactile'^^  center;  centers 
for  smell  and  taste ;  a  motor  speech  center ;  and  centers  for 
movements  of  the  limbs  and  face. 

The  motor  center  of  articulate  speech  is  one  of  the  most 
definitely  settled  points  in  cerebral  localization. 

There  are  two  forms  of  aphasia,  which  are  clinically  recog- 
nized, viz.,  the  amnesic  or  sensory,  and  the  ataxic  or  motor ^ 
varieties.  In  the  former,  the  memory  of  words  is  utterly  lost, 
so  that  the  patient  is  not  only  unable  to  express  his  ideas  in 
articulate  sounds,  but  he  is  also  unable  to  write  them,  thus 
showing  that  the  words  themselves  have  been  forgotten.  In 
the  ataxic  variety,  however,  the  memory  of  spoken  or  written 
words  still  remains,  but  the  ability  to  so  coordinate  the  mus- 
cles of  articulation  as  to  pronounce  the  words  is  impaired, 
so  that  the  person  so  afflicted  can  write  his  ideas  intelligently, 
but  can  not  utter  them. 

Ai:)hasia  is  not  to  be  confounded,  however,  with  other  dis- 
eases where  the  ability  to  talk  is  apparently  absent,  such  as 
occurs  in  the  insane  (who  often  refuse  to  converse  from  mere 
obstinacy),  in  those  types  of  paralysis  which  affect  the  entire 
muscular  mechanism  associated  with  articulation,  in  hysteria, 
chorea,  and  nervous  affections,  and  in  the  aphonia  of  laryn- 
geal inflammation  or  paralysis. 

The  credit  of  the  great  discovery  that  the  motor  center  of 
articulate  speech  could  be  localized  in  the  third  convolution 
of  the  left  anterior  lobe  of  the  cerebrum  is  generally  awarded 
to  Broca.''  Some  twenty-five  years  before  he  made  the  pro- 
fession alive  to  the  investigation  of  the  subject,  however,  the 
same  motor  impairment  or  loss  of  speech  was  shown  to  be  a 
frequent  accompaniment  of  hemiplegia  of  the  right  side  of 
the  body  by  Bouillaud  and  Marc  Dax ' ;  and  in  1863,  or  there- 

»  "Cbl.  med.  Wiss.,"  1874.  '  Broca,  "Bui.  de  la  Soc.  Anat.,"  Aug.,  1861. 

*  A  paper  read  before  the  Medical  Congress  at  Montpellier  in  1836. 


TEE  BRAIK 

about,  the  views  of  Broca  and  of  Hughlings- Jackson '  were 
given  to  the  profession,  in  which  they  both  limit  the  lesion 
of  motor  aphasia  to  the  parts  supplied  by  the  left  middle  ' 
cerebral  artery.  In  1863,  the  investigations  also  of  the  son  \ 
of  Marc  Dax '  located  the  lesion  somewhere  in  the  anterior  or 
middle  portion  of  the  frontal  lobe  of  the  left  side,  and  the 
results  of  still  more  recent  investigations  upon  the  subject 
seem  to  point  to  the  *' island  of  Keil"  as  a  frequent  seat  of 
this  peculiar  type  of  paralysis. 

Viewing  the  fact  that  articulate  speech  is  a  thing  learned 
by  use,  it  has  been  suggested  that,  in  most  persons,  one  side 
of  the  brain  only  has  been  educated  for  that  purpose ;  that 
we  are,  in  fact,  left-brained  in  respect  to  speech  in  the  same       ' 
way  that  we  are  right-handed  in  respect  to  many  bodily 
movements.'     In  support  of  this  theory  the  physiological       ; 
fact  is  adduced  that,  in  most  people,  the  left  hemisphere 
of  the  cerebrum  is  larger  and  more  convoluted  than  the       \ 
right.  .  ^\ 

While  it  is  demonstrated  that  the  cerebral  lesion  in  apha- 
sia involves,  in  the  great  majority  of  cases,  the  left  side,  still 
there  have  been  several  cases  recorded  where  the  right  side 
has  been  shown  to  have  been  the  seat  of  disease.*    Such  dis- 
coveries tend  to  cast  a  doubt  upon  the  left  side  being  more   ^  m 
closely  connected  with  the  power  of  articulate  speech  than 
the  right  side.     Some  anatomists  have  endeavored  to  explain 
the  frequency  of  the  lesion  upon  the  left  side  of  the  brain  as        i 
a  result  of  the  fact  that  emboli  (which  are  the  most  frequent  ^i 
cause  of  the  disturbance  to  those  parts  supplied  by  the  middle  n| 
cerebral  artery)  find  a  much  more  direct  course  upward  upon        ! 
the  left  side  than  upon  the  right,  in  consequence  of  the  angle       ; 
at  which  the  innominate  artery  leaves  the  arch  of  the  aorta, 
which  favors  the  passage  of  an  embolus  by  rather  than  into  "^ 
its  mouth  ;  while  the  left  carotid  artery  is  situated  at  the  |*^ 

'  Hughlings- Jackson,  "  Clinical  and  Physiological  Researches  on  the  Nervous  Sys- 
tem." 

'  M.  G.  Dax,  as  quoted  by  Dodds  and  A.  Flint,  Jr. 

'  Mich.  Foster,  op.  cit. ;  Ferrier,  "  Functions  of  the  Brain." 

*  Boyd,  Broadbent,  Bateman,  Meissner,  Bertin,  Seguin,  and  others. 


APHASIA,  AS  A  SYMPTOM.  73 

highest  part  of  the  arch,  and  its  mouth  is  so  directed  as  to 
arrest  rather  than  avoid  any  floating  particles  in  the  blood 
current.  In  case  of  such  movable  particles  being  arrested 
either  by  the  innominate  or  left  carotid  arteries,  the  most 
direct  course  in  both  instances  will  be  toward  the  middle  cere- 
bral arteries,  and  thus  aphasia  will  generally  be  produced 
with  hemiplegia  upon  the  side  opposite  to  that  where  the 
embolus  may  be  found. 

The  following  deductions  relative  to  disorders  of  speech 
may  aid  in  recognizing  the  seat  of  the  lesion  during  the  life 
of  the  sufferer : 

1.  The  cortex  of  the  posterior  part  of  the  third  frontal 
con'Golution,  and  possibly  also  the  island  of  Reil^  presides 
over  the  coordination  of  the  muscular  acts  necessary  to 
speech.  It  also  stores  the  memories  of  such  acts,  so  that  any 
combination  of  articulate  sounds  can  be  voluntarily  repro- 
duced when  the  proper  form  of  excitation  is  furnished  (chief- 
ly in  response  to  sight  or  sound  impressions). 

This  center  is  connected  by  "associating  fibers"  with  the 
centers  of  hearing  (first  temporal  convolution)  and  those  of 
sight  (the  occipital  convolutions).  It  is  also  put  in  com- 
munication with  the  nuclei  of  the  facial^  hypoglossal., 
the  pneumogastric,  and  gloss o-pharyngeal  nerves  (within 
medulla)  by  means  of  two  distinct  tracts  of  fibers,  viz.,  the 
"  hypoglossal  cerebral  tract "  and  the  so-called  "  speech  tract," 
which  pass  through  the  internal  capsule,  the  crus,  and  the 
pons,  in  order  to  reach  the  medulla. 

Thus,  this  cortical  center  of  coordinated  speech-movements 
is  capable  of  receiving  excitation  from  the  centers  of  hearing, 
when  replies  to  spoken  language  are  demanded ;  and  from 
the  centers  of  sight,  when  written  or  printed  language  calls 
for  a  verbal  response.  It  is  also  put  in  direct  communica- 
tion with  the  nerves  which  preside  over  the  apparatus  of 
speech  (whose  nuclei  of  origin  are  situated  within  the  me- 
dulla). 

2.  The  form  of  amnesic  aphasia  known  as  ''word-deaf- 
ness^'' (Kussmaul)  indicates  the  existence  of  a  lesion  of  the 


74  THE  BRAIN.  ^^^^^I^M 

first  temporal  convolution'  of  the  left  side,  which  has  im 
paired  the  memories  of  spoken  language.  Hearing  may  not 
be  impaired,  although  the  appreciation  of  words,  music,  etc., 
may  be  totally  absent. 

3.  The  condition  known  as  ''  word-hlindness'^''  (Kussmaul) 
indicates  the  existence  of  a  lesion  of  the  left  occipital  lobe, 
which  has  impaired  the  memories  of  written  or  printed  sym- 
bols of  language,  numerals,  familiar  objects,  etc. 

4.  The  condition  termed  "paraphasia''''  by  Kussmaul  (in 
which  the  amnesic  and  ataxic  varieties  of  aphasia  seem  to  be 
peculiarly  combined)  may  be  excited  by  a  lesion  which  inter- 
feres with  the  action  of  the  associating  tracts  of  fibers,  be- 
tween the  areas  of  hearing  or  sight  and  the  motor  speech  cen- 
ter of  Broca  (Wernicke). 

6.  The  condition  of  imperfect  speech  termed  "  anarthria  " 
is  produced  by  a  lesion  of  the  medulla,  which  interferes  with 
the  functions  of  the  nuclei  of  the  cranial  nerves  associated 
with  speech.  It  is  occasionally  observed  in  connection  with 
focal  lesions  of  the  floor  of  the  fourth  ventricle.  These  cases 
are  to  be  differentiated  from  aphasia  of  cortical  origin  by  the 
coexistence  of  other  symptoms  produced  by  the  medullary 
lesion. 

6.  In  order  to  properly  pronounce  any  word,  it  is  essential 
that  both  the  cortical  center  of  speech,  and  also  the  nuclei  of 
the  medulla,  which  are  associated  with  it,  must  be  called  into 
action.  J^fi! 

7.  The  peculiar  course  which  the  fibers  of  the  ''speech 
tract "  take  within  the  cerebral  hemisphere  sheds  light  upon 
these  reported  cases  of  aphasia  where  the  lesion  was  situated 
posterior  to  the  center  of  Broca.  These  fibers  run  from  the 
third  frontal  gyrus  close  to  the  surface  of  the  hemisphere, 
and  in  an  antero-posterior  direction  (passing  in  the  external 
capsule),  to  reach  the  posterior  part  of  the  lenticular  nucleus. 
They  dip  at  this  point  into  the  posterior  part  of  the  internal 

*  In  right-handed  subjects  the  left  hemisphere,  and  in  left-handed  subjects  the  right 
hemisphere,  seems  to  monopolize  the  function  of  sound-interpretation  to  the  speech 
center. 


A 


APHASIA,  AS  A  SYMPTOM.  75 

capsule.  They  then  pass  through  the  middle  part  of  the  crus 
and  pons  to  the  medulla  (Wernicke).  Within  the  internal 
capsule,  the  fibers  of  the  ''speech  tract"  lie  (according  to  this 
observer)  between  the  optic  fibers  and  those  of  the  sensory 
tract. 

8.  Should  aphasia  be  developed  as  a  result  of  a  lesion  of 
the  internal  capsule,  hemianopsia  or  hemiancesthesia  would 
be  liable  to  coexist^  on  account  of  the  relationship  of  the  optic 
and  sensory  fibers  of  the  capsule  to  the  speech  tract. 

9.  It  is  possible  to  have  aphasic  symptoms  develop  as  a 
result  of  a  lesion  within  the  crus  or  pons.  This  is  because 
the  speech  tract  passes  through  them  to  reach  the  medulla. 

10.  The  cortical  centers  of  hearing,  smell,  and  taste  are 
probably  associated  (wholly  or  in  part)  with  the  correspond- 
ing organ  of  the  opposite  side.  Hence,  we  may  clinically 
refer  an  abolition  of  the  function  of  hearing  (when  due  to  a 
cortical  lesion)  to  the  hemisphere  opposed  to  the  deaf  ear. 
"Word-deafness"  may  ensue,  however,  when  the  centers  of 
hearing  of  only  one  cerebral  hemisphere  are  involved.  In 
right-handed  subjects,  the  left  superior  temporal  convolution 
appears  to  govern  this  function ;  while,  in  left-handed  sub- 
jects, the  right  superior  temporal  convolution  assumes  it. 
This  is  probably  due  to  the  fact  that  the  hemisphere  which  is 
the  most  exercised  becomes  more  rapidly  developed. 

11.  When  the  third  frontal  convolution  is  alone  diseased, 
the  patient  will  be  able  to  understand  spoken  or  written  ques- 
tions perfectly,  but  will  not  be  able  to  coordinate  the  move- 
ments of  the  speech  apparatus  requisite  to  a  reply. 

12.  When  the  superior  temporal  convolution  is  alone  dis- 
eased, the  patient  can  not  recognize  or  properly  interpret 
spoken  language.  He  may,  however,  be  able  to  repeat  single 
words  when  propounded,  but  not  sentences.  Exclamations 
of  various  kinds  may  be  uttered  by  these  subjects  when  irri- 
tated or  distressed ;  but  they  are  more  or  less  involuntary, 
and  often  irrelevant. 

13.  When  the  associating  fibers  between  the  different 
centers  functionally  connected  with  speech  are  alone  diseased, 


THE  BRAIN, 


the  patient  can  comprehend  written  or  spoken  language  per- 
fectly ;  but,  in  talking,  such  a  subject  is  apt  to  interpolate, 
from  time  to  time,  some  irrelevant  and  unexpected  word  in  a 
sentence  in  place  of  the  one  desired.  •    i 

The  Pre-frontal  Lobes. — There  are  innumerable  cases 
on  record  where  the  frontal  lobes  anterior  to  the  motor  cen- 
ters have  suffered  frightful  lacerations  and  loss  of  substance, 
and  yet  recovery  has  taken  place ;  and  where  disease  of  an 
extensive  character  has  also  produced  negative  results,  both 
as  regards  motion  and  sensation.  This  region  is  often  called 
the  "prefrontal  lobe." 

A  crowbar  has  been  shot  through  the  head,  and  recovery  *^' 
followed.'  Again,  Bouillaud'  reports  the  passage  of  a  bullet 
through  the  frontal  lobes  with  a  like  result,  and  with  no  effect 
upon  sensation  or  motion.  Cases  somewhat  similar  are  re- 
corded by  Trousseau,'  Congreve  Selwyn,*  Pitres,'  Morgagni, 
Marot,*  Tavignot,  and  others,  all  of  which  go  to  prove  the 
possibility  of  the  most  serious  injury  to  this  portion  of  the 
cerebrum  without  symptoms  indicative  of  its  presence.  On 
the  other  hand,  numerous  cases  of  haemorrhage  and  of  abscess 
within  the  frontal  lobes,  as  reported  by  Andral,'  Hertz,  Reed, 
Begbie,  and  others  (quoted  by  Charcot  and  Ferrier),  show  the 
same  absence  of  positive  diagnostic  symptoms  either  in  sen-j^ 
sory  or  motor  paralysis. 

From  such  sources  of  clinical  reasoning,  as  well  as  from 
the  physiological  deductions  which  experiments  upon  ani- 
mals have  taught,  the  following  conclusion  of  Ferrier'  is  of 
value  to  the  reader:  ''With  such  evidence  before  us,  we  can 
not  regard  cases  in  which,  with  lesions  of  the  prsefrontal 
lobes,  sensation  or  motion  has  been  affected  as  other  thaiiJSl 
cases  ^  coexistence  or  of  multiple  lesions^  whether  organic 
or  functional." 


m 


'  Bigelow,  "Am.  Jour,  of  Med.  Sciences,"  July,  1850;  Harlow,  "Recovery  from  the 

Passage  of  an  Iron  Bar  through  the  Head";  "Reports  of  Mass.  Med.  Soe.,"  Boston,  1869. 

'  Op  cit.  3  Quoted  by  Peter  and  Ferrier. 

*  "  London  Lancet,"  February  28,  1838.  '  "  Lesions  du  Centre  Ovale,"  1877. 
«  "  Prog.  M6d.,"  February  26  and  June  3,  1876.     '  "  Clinique  M6dicale." 

*  "  Localization  of  Cerebral  Disease,"  New  York,  1880. 


MOTOR  AREA    OF  CEREBRUM.  77 

The  Motoe  Regions  of  the  Cerebeum. — It  may  now  be 
positively  stated  that  the  bases  of  the  three  frontal  conTolu- 
tions^  the  convolutions  which  bound  the  fissure  of  Rolando, 
and  the  para-central,  lobule  upon  the  internal  surface  of  each 
hemisphere  of  the  cerebrum,  are  distinctly  motor  in  their 
function.  The  distribution  of  the  middle  cerebral  artery  to 
this  region  gives  to  that  vessel  an  importance  not  before  ap- 
preciated ;  since  it  is  now  known  that  the  four  or  five  branch- 
es which  are  given  off  from  the  main  artery  each  nourish  a 
separate  area  of  brain  substance,  and  that  emboli  may  ob- 
struct either  the  trunk  or  some  of  its  individual  branches.  It 
is  thus  possible  to  explain  how  the  basal  ganglia  may  still 
perform  their  functions  while  other  parts  supplied  by  some  of 
the  cortical  branches  may  be  impaired. 

The  preponderance  of  clinical  testimony  goes  to  show  that 
most  of  the  destructive  lesions  which  are  associated  during 
life  with  paralysis  of  voluntary  motion  are  confined  to  this 
motor  area,  although  a  rare  case  is  on  record'  where  the 
motor  area  was  the  seat  of  cystic  disease,  and  still  voluntary 
motion  remained  unaffected.  It  is  a  matter  of  great  doubt 
whether  the  gray  matter  of  the  convolutions  was  impaired, 
even  in  this  case,  in  spite  of  the  existing  lesion. 

The  effect  of  very  extensive  lesions  affecting  the  motor 
area  of  the  monkey  (which  is  commonly  used  for  experiments, 
as  the  nearest  approach  to  the  type  of  mankind)  may  be  sum- 
marized as  follows:  1.  A  hemiplegia,  which  is  at  first  abso- 
lute ;  2.  An  improvement  in  associate,  alternating,  or  bilateral 
movements,  but  no  improvement  in  voluntary  motion. 

Respecting  this  point,  I  quote  from  Ferrier's  work  as  fol- 
lows: 

**  As  examples  of  the  improvement  which  follows  the  on- 
set of  the  hemiplegia,  the  hand  becomes  more  paralyzed  than 
the  arm,  the  arm  more  than  the  leg,  and  the  lower  facial 
movements  more  than  the  upper;  while  the  muscles  of  the 
trunk  are  scarcely,  if  at  all,  affected."' 

^  Samt,  "  Archiv  fur  Psychiatrie,"  1874. 

2  Ferrier,  "  Localization  of  Cerebral  Disease." 


78  TBE  BRAIN, 

In  man  the  hemiplegia  is  exhibited  chiefly  upon  the  side 
opposite  to  the  existing  lesion/  if  the  motor  area,  the  corpus  i 
striatum,  or  the  motor  part  of  the  internal  capsule  be  the 
seat  of  disease.  This  paralysis  is  often  accompanied  by  con-  ' 
vulsive  muscular  movements  or  rigidity  oi  the  paralyzed  ! 
parts  in  its  early  stage,  and,  later  on,  by  rigidity  and  motor  .  ; 
sclerosis.  \ 

The  researches  of  Pitres'  have  shown  that  the  same  results      j 
as  those  dependent  upon  a  lesion  of  the  gray  matter  of  the    ." 
convolutions  within  the  motor  area  follow  when  the  lesion 
affects  the  white  substance  of  the  brain'  which  intervenes 
between  the  gray  matter  covering  the  motor  area  and  the 
basal  ganglia  beneath  them,  and  he  therefore  urges  a  system  ^\ 
of  nomenclature  of  the  different  portions  of  the  "centrum 
ovale,"  based  upon  sections  of  the  brain  made  in  certain  re-  „^j 
gions  so  as  to  show  special  parts.  £?i 

It  is  by  means  of  these  researches  that  we  are  enabled  to  ^  \ 
explain  those  cases  where  rigidity  or  muscular  spasms  accom- 
pany an  attack  of  hemiplegia,  from  an  effusion  into  the  lat- 
eral ventricles  of  the  brain ;  and  where  cerebral  softening  or  \ 
hcemorrhage^  which  does  not  affect  the  gray  matter  of  the  j 
convolutions  or  the  basal  ganglia,  produces  a  permanent  pa-.  ^| 
ralysis  of  the  side  of  the  body  opposite  to  the  lesion.  3- 

When  sudden  hemiplegia  occurs  as  a  result  of  hsemor-  ; 
rhage  into  or  traumatism  of  some  portion  of  the  motor  area,  \ 
the  condition  of  paralysis  is  liable  to  improve  in  those  regions  i 
of  the  body  where  the  special  motor  center  of  that  part  re-  ^ji 
mains  unimpaired,  but  the  paralysis  will  usually  remain  per-  ; 
manent  in  that  part  of  the  body  whose  motor  center  is  de-  i 
stroyed.  This  fact,  when  properly  interpreted,  may  often  j 
prove  a  most  valuable  guide  in  diagnosis.  Hl 

Special  Centers  of  Motion.— kx  the  base  of  the  first  fron-  ■ 
tal  convolution.,  and  extending  slightly  into  the  second  fron-       i 

'  The  fact  that  all  the  motor  fibers  do  not  decussate  in  the  medulla  oblongata  (Flech-  ^  | 
Big)  explains  the  exceptions  to  this  rule. 

'  "  L6sions  du  Centre  Ovale,"  Paris,  1877. 

'  This  portion  contains  the  fibers  of  the  internal  capsule  radiating  to  reach  the  motor  H  i^ 
regions  of  the  cortex.     (See  Fig.  8.)  B-^ 


SPECIAL    CENTERS  OF  MOTION. 


79 


tal  comolution^  in  the  brain  of  a  monkey,  a  distinct  center 
may  be  located  which  exerts  a  special  influence  upon  the 


Fig.  25. — Side  view  of  the  brain   of  man  and  the  areas  of  the  cerebral   convolutions. 

(After  Ferrier.) 

1  (on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind-limb 
as  in  walking ;  2,  3,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando),  com- 
plex movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swimming; 
a,  6,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  individual  and 
combined  movements  of  the  fingers  and  wrist  of  the  opposite  hand ;  prehensile 
movements ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolution),  exten- 
sion forward  of  the  opposite  arm  and  hand  ;  6  (on  the  upper  part  of  the  antero-parie- 
tal  or  ascending  frontal  [anterior  central]  convolution),  supination  and  flexion  of  the 
opposite  fore-arm  ;  ^  (on  the  median  portion  of  the  same  convolution),  retraction  and 
elevation  of  the  opposite  angle  of  the  mouth  by  means  of  the  zygomatic  muscles ;  8 
(lower  down  on  the  same  convolution),  elevation  of  the  ala  nasi  and  upper  Hp  with 
depression  of  the  lower  lip,  on  the  opposite  side ;  9,  10  (at  the  inferior  extremity  of 
the  same  convolution,  Broca's  convolution),  opening  of  the  mouth  with  9,  protrusion, 
and  10,  retraction  of  the  tongue — region  of  aphasia,  bilateral  action;  11  (between 
10  and  the  inferior  extremity  of  the  postero-parietal  convolution),  retraction  of  the 
opposite  angle  of  the  mouth,  the  head  turned  slightly  to  one  side;  12  (on  the  poste- 
rior portions  of  the  superior  and  middle  frontal  convolutions),  the  eyes  open  widely, 
the  pupils  dilate,  and  the  head  and  eyes  turned  toward  the  opposite  side;  13,  13  (on 
the  supra-marginal  lobule  and  angular  gyrus),  the  eyes  move  toward  the  opposite  side 
with  an  upward  13,  or  downward  13-  deviation;  the  pupils  generally  contracted  (cen- 
ter of  vision,  according  to  the  author) ;  14  (of  the  infra-marginal,  or  superior  [first] 
temporo-sphenoidal  convolution),  pricking  of  the  opposite  ear,  the  head  and  eyes 
turn  to  the  opposite  side,  and  the  pupils  dilate  largely  (center  of  hearing).  Ferrier, 
moreover,  places  the  centers  of  taste  and  smell  at  the  extremity  of  the  temporo- 
sphenoidal  lobe,  and  that  of  touch  in  the  gyrus  uncinatus  and  hippocampus  major. 


head  and  eyes.     Thus,  to  quote  from  Ferrier,  whose  research- 
es have  been  remarkable  for  the  apparent  accuracy  of  many      ■ 
of  his  deductions,  stimulation  of  this  center  causes  "•  eleva-      \ 
Hon  of  the  eyelids^  dilatation  of  the  pupils,  conjugate  devi- 
ation of  the  eyes,  and  turning  of  the  head  toward  the  oppo-      , 
site  side:'     (See  No.  12  in  Fig.  26.)  vu;! 

That  this  same  center  seems  to  exist  in  the  human  brain  is  ' 
to  be  inferred  from  the  cases  where  a  bilateral  deviation  of  \ 
the  eyes  has  been  observed,  which,  in  some  cases,  has  also  1 
been  associated  with  a  lateral  deflection  of  the  head.  This  ; 
subject  has  excited  the  interest  of  Hughlings- Jackson,'  Priest-  ! 
ley  Smith,'  Ferrier,'  and  Charcot,*  and  cases  which  seem  to 
sustain  the  theory  of  an  oculo-motor  function  in  the  frontal  - 
convolutions  have  been  reported  by  Chouppe,  Landouzy,'ffl| 
Carroll,  Smith,  Horsley,  and  others.  An  effort  has  been  v;!i 
made  to  explain  these  ocular  symptoms  by  some  associa-  ; 
tion  with  the  angular  gyrus,  but  apparently  without  much  ' 
ground.  -^*) 

The  center  of  motion  for  the  muscles  of  the  limbs  is  not  \ 
yet  as  positively  ascertained  as  the  oculo-motor  center,  al-  ' 
though  some  interesting  experiments  have  been  made  to  \ 
decide  whether  the  corresponding  point  of  the  brain  of  man  ; 
is  analogous,  in  its  control  over  the  leg,  to  that  of  the  monkey  ! 
tribe.  As  an  example  of  the  ingenuity  shown  in  research,  i 
Bourdon "  and  Luys '  have  endeavored  to  demonstrate  atrophy 
of  certain  parts  of  the  brain  after  amputation  of  the  limbs,  j 
and  thus  indirectly  to  prove  the  normal  use  of  the  parts  M\ 
which  had  atrophied  from  disuse.  The  use  to  which  the  j 
monkey  puts  his  tail,  since  it  serves  the  purpose  of  an  addi-  j 
tional  hand  in  some  instances,  renders  the  application  of  i 
movements  of  that  organ  to  those  of  man  a  matter  of  appar-  \ 
ent  difficulty,  and  the  center  of  motion  for  the  tail  of  the  ^^J 

'  "  Ophthalmology  in  its  Relations  to  General  Medicine,"  *'  Lancet,"  May,  1877. 

'  "  Bilateral  Deviations  of  the  Eyes,"  "  Birmingham  Med.  Review,"  1875. 

'  Op.  cit.  *  Op.  at.  JQ^ 

*  "  B16pharoptose  c6r6brale,"  "Arch.  G6n.  de  M6d.,"  Aug.,  1877.  .^JM 

*  "  Rechcrches  cliniqucs  sur  les  centres  moteurs,"  Paris,  1877 
'  "  Functions  of  the  Brain,"  New  York,  1882. 


SPECIAL   CENTERS  OF  MOTION. 


81 


Fig.  26. —  Upper  view  of  the  brain  of  man  and  the  situation  of  areas  of  the  cerebral 
convolutions.     (After  Ferrier.) 

1  (on  the  postero-parietal  [superior  parietal]  lobule),  advance  of  the  opposite  hind-limb 
as  in  walking;  2,  3,  4  (around  the  upper  extremity  of  the  fissure  of  Rolando),  com- 
plex movements  of  the  opposite  leg  and  arm,  and  of  the  trunk,  as  in  swimming ;  a, 
6,  c,  d  (on  the  postero-parietal  [posterior  central]  convolution),  individual  and  com- 
bined movements  of  the  fingers  and  wrist  of  the  opposite  hand ;  prehensile  move- 
ments ;  5  (at  the  posterior  extremity  of  the  superior  frontal  convolution),  extension 
forward  of  the  opposite  arm  and  hand ;  6  (on  the  upper  part  of  the  antero-parietal 
or  ascending  frontal  [anterior  central]  convolution),  supination  and  flexion  of  the 
opposite  fore-arm ;  7  (on  the  median  portion  of  the  same  convolution),  retraction 
and  elevation  of  the  opposite  angle  of  the  mouth  by  means  of  the  zygomatic 
muscles ;  8  (lower  down  on  the  same  convolution),  elevation  of  the  ala  nasi  and 
upper  lip  with  depression  of  the  lower  lip,  on  the  opposite  side ;  9,  10  (at  the  in- 
ferior extremity  of  the  same  convolution,  Broca's  convolution),  opening  of  the 
mouth  with  9,  protrusion,  and  10,  retraction  of  the  tongue — region  of  aphasia, 
bilateral  action;  11  (between  10  and  the  inferior  extremity  of  the  postero-parietal 
convolution),  retraction  of  the  opposite  angle  of  the  mouth,  the  head  turned  slightly 
to  one  side ;  1 2  (on  the  posterior  portions  of  the  superior  and  middle  frontal  con- 
volutions), the  eyes  open  widely,  the  pupils  dilate,  and  the  head  and  eyes  turn 
toward  the  opposite  side ;  13,  13  (on  the  Supra-marginal  lobule  and  angular  gyrus),  the 
eyes  move  toward  the  opposite  side  with  an  upward  13,  or  downward  13*  deviation — 
the  pupils  generally  contracted  (center  of  vision) ;  14  (of  the  infra-marginal,  or  supe- 
rior [first]  temporo-sphenoidal  convolution),  pricking  of  the  opposite  ear,  the  head 
and  eyes  turn  to  the  opposite  side,  and  the  pupils  dilate  largely  (center  of  hearing). 
Ferrier,  moreoVer,  places  the  centers  of  taste  and  smell  at  the  extremity  of  the  tem- 
poro-sphenoidal lobe,  and  that  of  touch  in  the  gyrus  uncinatus  and  hippocampus  major. 


82  THE  BRAIK 

monkey  can  hardly  be  applied  to  the  brain  of  man  without 
bringing  comparative  anatomy  into  prominence. 

Paralysis  of  the  leg,  when  dependent  solely  upon  cerebral 
lesions,  is  seldom  separated  from  a  similar  condition  of  the 
upper  extremity,  although  a  few  rare  cases  of  that  character 
are  on  record  ;  but  the  rule  of  Lucas  Championniere  may  be 
considered  as  approximately  correct,  viz.,  that,  to  expose  the 
center  of  motion  for  the  muscles  of  the  leg,  it  is  necessary 
to  trephine  over  the  upper  extremity  of  the  fissure  of 
Rolando ^  Horsley"  locates  the  center  for  the  big  toe  in  the 
paracentral  lobule,  and  he  includes  the  following  parts  in  the 
motor  area  of  the  lower  limb  :  the  upper  part  of  the  two  cen- 
tral convolutions,  the  superior  parietal  convolution,  and  the 
base  of  the  superior  frontal  gyrus. 

The  centers  of  motion  for  the  muscles  of  the  different  re- 
gions of  the  upper  extremity  occupy  a  much  larger  space 
upon  the  surface  of  the  cerebrum  than  those  of  the  lower  ex- 
tremity, as  might  have  been  expected  when  we  consider  the 
amount  of  intelligence  which  the  hand  exhibits.*  Ferrier 
has  pointed  out  certain  motor  areas  for  the  various  move- 
ments of  extension,  adduction  and  retraction,  supination  and 
flexion,  and  centers  for  the  actions  of  the  wrist  and  finger 
muscles.* 

The  close  proximity  of  those  centers  which  control  the 
facial  and  oral  muscles  to  the  centers  governing  the  motions 
of  the  hand  possibly  explains  why  movements  of  retraction 
of  the  mouth  occur  when  the  hand  is  brought  into  powerful 
action ;  and  also  the  fact  that  paralysis  of  certain  groups  of 
muscles  situated  in  the  upper  extremity  are  commonly  asso- 
ciated with  some  form  of  facial  paralysis. 

From  a  careful  analysis  of  cases  where  paralysis  of  the 
upper  extremity  was  confined  to  certain  sets  of  muscles,  the 

'  For  the  surgical  guide  to  locate  the  situation  of  that  fissure  upon  the  exterior  sur- 
face of  the  skull  of  a  living  subject,  the  reader  is  referred  to  a  subsequent  page  of  this 
chapter. 

*  "  Am.  Jour.  Med.  Sciences,"  April,  1887.       »  Sir  Charles  Bell,  "  The  Human  Hand." 

*  In  pages  79,  81  of  this  volume,  the  centers  of  Ferrier  are  shown  in  a  diagrammatic 
cut,  and  the  special  action  of  each  given  in  the  descriptive  text  which  accompanies  it. 


SPECIAL   CENTERS  OF  MOTION.  83 

results  seem  to  point  to  the  ascending  parietal  and  the  upper 
portion  of  the  ascending  frontal  convolutions  of  the  cere- 
bram,  as  the  probable  seat  of  disease ;  and  lesions  of  the 
ascending  parietal  convolution  have  been  found,  both  by  ex- 
perimental research  and  by  pathological  deduction,  to  affect 
the  hand  in  particular.  In  further  support  of  this  statement, 
the  results  of  the  examination  of  the  brains  of  persons  who 
had  suffered  amputation  of  the  hand,*  or  who  had  been  char- 
acterized by  a  congenital  absence  of  that  member,'*  show  an 
atrophy  of  the  part  designated  by  the  experiments  of  Ferrier 
as  the  motor  center  for  its  movements. 

According  to  the  later  observations  of  Horsley,  the  motor 
centers  for  the  upper  limb  may  be  subdivided  as  follows : 

1.  The  uppermost  part  controls  the  shoulder. 

2.  Below  and  posteriorly  to  the  shoulder  centers,  the  elbow 
is  represented. 

3.  Still  farther  below  and  anteriorly,  the  wrist  centers. 

4.  Lowest  of  all,  anteriorly,  the  finger  centers. 

5.  Lowest  of  all,  posteriorly,  the  thumb  centers. 

The  motor  centers  of  the  facial  muscles  occupy  a  region 
in  close  proximity  to  those  of  the  arm  and  hand  ;  and  it  is  an 
exception  to  the  general  rule  to  observe  paralysis  confined 
exclusively  to  the  face,  since  the  muscles  of  some  part  of  the 
upper  extremity  are  generally  affected  simultaneously. 

Horsley  subdivides  the  cortical  area  associated  with  facial 
movements  as  follows : 

1.  The  upper  and  anterior  part  governs  the  upper  part  of 
the  face  and  the  angle  of  the  mouth. 

2.  The  anterior  half  of  the  lower  part  governs  the  move- 
ments of  the  vocal  cords. 

3.  The  posterior  half  of  the  lower  part  governs  the  lower 
part  of  the  face  and  the  foor  of  the  mouth. 

This  observer  includes  the  lower  third  of  the  ascending 
frontal  and  ascending  parietal  convolutions  in  the  cortical 
area  of  the  face. 

*  Reported  by  Bourdon,  *'  Centres  moteurs  des  membres,"  Paris,  1877. 
2  Gowers,  article  in  "  Brain,"  1878,  Part  III. 


84  THE  BRAIN. 

It  may  be  also  noticed,  with  some  degree  of  practical  in 
terest,  that  motor  aphasia  is  a  common  associate  of  either  of 
these  types  of  localized  paralysis,  since  the  center  of  Broca  is 
liable  to  be  also  involved  from  its  close  relation  to  both  the 
centers  of  the  face,  arm,  and  hand/  It  is  considered  by  some 
authorities  that  the  absence  of  aphasia,  in  cases  where  the 
muscles  of  the  face,  arm,  or  hand  are  paralyzed,  is  probably 
confined  to  lesions  affecting  only  the  right  side  of  the  cere- 
brum. 

The  lesions  in  which  aphasia  exists  have  been  considered 
somewhat  at  length  in  previous  pages  of  this  chapter.  The 
fact  that  most  of  the  clinical  cases  recorded  have  failed  thus 
far  to  overthrow  the  discovery  of  Broca  seems  to  place  it  upon 
a  footing  above  that  of  mere  empirical  generalization.  Cases 
have  been  reported  where  aphasia  has  been  the  result  of  fract- 
ure of  the  left  side  of  the  skull  in  the  region  of  the  frontal 
lobes,'  and  also  where  recovery  of  the  power  of  speech  fol- 
lowed the  operation  of  trephining,'  but  it  occurs  most  fre- 
quently as  the  result  of  embolic  obstruction  of  the  middle 
cerebral  artery  or  of  some  of  its  branches.* 

Diagnosis  of  Cortical  Motor  Paralysis. — The  effects  of 
lesions  which  involve  the  corpus  striatum  of  either  side,  or 
the  motor  bundles  of  the  internal  capsule  of  the  cerebrum, 
differ  but  little  from  those  of  lesions  which  are  confined  to 
the  motor  area  of  the  cerebral  convolutions,  since  the  fibers 
which  are  affected  in  either  case  are  the  same. 

After  the  effects  of  the  shock  of  the  attack  have  passed 
away,  the  muscles  which  are  paralyzed  are  usually  those 
which  are  the  most  completely  under  the  control  of  volition  ; 
thus  the  lower  muscles  of  the  face  are  more  affected  than 
those  upon  the  forehead  or  of  the  eyelids,  since  the  lower 
facial  muscles  are  by  far  the  most  voluntary  ;  the  muscles  of 
the  hand  are  very  markedly  affected,  even  more  than  those  of 

*  See  the  relation  of  the  facial  centers,  Nos,  7,  8,  11,  to  those  of  the  arm  and  hand, 
Nos.  4,  6,  6,  a,  6,  c,  c?,  and  to  the  oro-lingual  centers,  Nos.  9,  10,  in  Fig.  25  of  this  volume* 

«  MacCormac,  "  Brain,"  18Y7,  Part  II. 

"'  Terrillon  and  Proust,  "  Acad,  de  Medecine,"  November,  1876. 

*  See  researches  of  Meissncr,  Charcot,  Vulpian,  Seguin,  Bertin,  and  others. 


i 


CORTICAL  MOTOR  PARALYSIS.  85 

the  arm  ;  and  the  muscles  of  the  upper  extremity  more  than 
those  of  the  lower. 

No  evidence  of  impairment  of  sensation  can  be  discovered, 
provided  that  the  posterior  third  of  the  internal  capsule  of 
the  cerebrum  has  escaped  injury.  The  nutrition  of  the  para- 
lyzed muscles  is  apparently  normal,  and  their  electric  con- 
tractility is  not  impaired. 

A  tendency  toward  rigidity  of  the  paralyzed  muscles  de- 
velops later  on  in  the  disease,  which  has  been  variously  ex- 
plained by  some  authors  (Charcot,  Bastian,  and  Bouchard)  as 
the  result  of  a  progressive  sclerosis^  which  descends  along 
the  motor  tract  of  the  pons  Varolii,  crus  cerebri,  medulla,  and 
the  spinal  cord  ;  while  the  researches  of  Hughlings- Jackson ' 
warrant  him  in  discarding  this  explanation  and  attributing 
it  to  an  unimpeded  cerebellar  influence,  which  is  no  longer 
controlled  by  the  cerebrum.  Both  of  these  hypotheses  are, 
however,  discarded  by  Buret,"  who  considers  the  rigidity  to 
be  the  result  of  simple  reflex  irritation.  It  will  in  no  way 
add  to  the  practicability  of  the  matter  contained  here  to  enter 
into  the  discussion  of  the  relative  demerits  of  these  theories, 
since  those  interested  in  the  subject  will  find  Ferrier's  work 
on  the  "Localization  of  Cerebral  Disease  "and  many  of  the 
advanced  works  upon  the  pathology  of  diseases  of  the  nervous 
system  to  contain  all  the  desired  information. 

One  of  the  most  valuable  signs  of  paralysis  dependent 
upon  a  lesion  of  the  cortex  is  the  fact  that  the  condition  is 
not  one  of  complete  hemiplegia,  but  rather  of  monoplegia,  in 
which  special  groups  of  muscles  only  are  deprived  of  volun- 
tary motion.  Thus,  for  example,  the  arm  and  leg  may  be 
affected  together ;  again,  the  arm,  hand,  and  face ;  the  arm 
alone ;  the  leg  alone ;  certain  movements  only  of  either  ex- 
tremity ;  and  all  other  possible  combinations. 

Paralysis  due  to  lesions  of  the  cortex  may  often  be  transi- 
tory, if  the  lesion  be  slight  and  superficial ;  or  it  may  be  per- 
manent, if  deep  and  impinging  upon  the  medulla.     It  is,  fur- 

^  "  Medical  Examiner,"  April  5,  1877.  =  a  Brain,"  Part  I,  1877. 


86  TEE  BRAIN. 

thermore,  frequently  associated  with  rigidity  in  its  ^^  ^ -^^ 
stages^  which  is  a  rare  occurrence  in  central  cerebral  disease.   |^  j 

In  attacks  of  paralysis  due  to  suddenly  developed  lesions  , 
of  the  cortex,  consciousness  is  less  frequently  lost  than  in  ] 
similar  lesions  of  the  central  ganglia.  Pain  of  a  local  char- -.'  j 
acter  within  the  head  is  often  complained  of  by  the  patient  ; 
spontaneously  with  the  attack,  or,  when  not  so,  it  may  be  ! 
sometimes  elicited  by  percussion  over  the  seat  of  the  exciting  j 
lesion.  '^■^*\ 

The  loss  of  consciousness  which  generally  accompanies  any 
sudden  lesion  of  the  central  ganglia  is  explained  by  Buret '  as 
due  to  a  rapid  displacement  of  the  cerehro- spinal  fluids  which 
in  turn  creates  a  general  disturbance  of  the  circulation  of  the 
cerebrum,  since  this  fluid  serves  to  establish  a  uniformity  of 
pressure  throughout  the  brain.  ^ 

Ferrier'  thus  briefly  summarizes  the  results  of  clinical  ob- 
servation bearing  upon  the  diagnosis  of  paralysis  dependent 
upon  destructive  lesions  of  the  cortex:  ^' While  we  can  not     ! 
be  quite  certain  of  the  position  or  extent  of  a  cortical  lesion     ] 
causing  a  sudden  and  complete  hemiplegia,  we  may  take  a     \ 
monoplegia  of  the  leg,  or  of  the  arm  and  leg,  as  an  indication     ] 
of  a  lesion  of  the  upper  extremity,  of  the  ascending  convolu-     ■ 
tions  close  to  the  longitudinal  fissure  ;  brachial  monoplegia^     j 
as  a  sign  of  a  lesion  in  the  upper  part  of  the  ascending  frontal 
convolution,  or,  if  the  paralysis  affect  the  hand  more  particu-     , 
larly,  of  the  ascending  parietal  convolution  ;  hrachio -facial 
monoplegia^  as  indicating  a  lesion  of  the  mid-fronto-parietal     | 
region ;  while  facial  and  lingual  monoplegia^  or  this  com-     : 
bined  with  aphasia,  indicates  a  lesion  of  the  lower  part  of  the     j 
ascending  frontal  convolution  where  the  third  frontal  joins     i 
with  it."*  v^l 

Irritative  Lesions  of  the  Motor  Area. — It  is  a  well-recog-  : 
nized  fact  in  clinical  experience  that  certain  symptoms,  which  j 
are  chiefly  of  a  convulsive  type,  are  dependent  upon  condi- 


'  "  Traumatismes  c6r6braux,"  Thfesc,  ]  878 ;  "  Aichiv.  de  Physiologic,"  1875.  ^^ 

^Op.ciL  pjji 

'  The  cut  (Fig.  26)  showing  the  motor  centers  will  tend  to  explain  these  deductiona..iy 


% 


SPASM  OF  CORTICAL   OEIOm,  87 

tions  wMcli  create  simply  irritation  of  certain  portions  of  the 
cerebrum,  without  any  actual  destruction  of  the  gray  or  white 
matter.  Among  the  various  conditions  which  are  especially 
liable  to  produce  such  local  irritation  may  be  mentioned 
syphilitic  meningo  encephalitis,  simple  inflammation  of  the 
same  character,  deposit  of  tubercle,  superficial  cysts  or  tu- 
mors of  a  more  solid  character,  spiculae  of  bone,  cicatrices 
from  wounds  of  previous  date,  suppuration  from  caries  and 
necrosis,  etc. 

In  the  year  1867,'  and  still  later,  in  the  year  1871,'  the 
general  statement  by  which  the  clinical  diagnosis  of  the  situa- 
tion of  irritative  lesions  of  the  cerebrum  might  be  assisted  was 
advanced  by  Callender,  "that  convulsive  attacks  were  most 
commonly  associated  with  superficial  lesions  of  the  cortex 
situated  in  the  immediate  vicinity  of  the  middle  meningeal 
artery."  Ferrier,  however,  concludes,  as  the  result  of  his  ex- 
tensive facilities  for  observation,  that,  while  this  may  be  use- 
ful as  a  general  rule,  still  affections  of  any  portion  of  the 
cortex  of  the  hemisphere  may  result  in  convulsions  of  the 
opposite  side  of  the  body,  and  he  adds  the  statement  that  the 
seat  of  an  irritative  lesion  can  be  less  accurately  determined 
than  one  of  a  destructive  character,  owing  to  the  difiiculty  of 
determining  the  extent  of  the  zone  in  which  vital  irritation 
concentrates  itself. 

Hughlings- Jackson '  has  contributed  much  to  the  pathol- 
ogy of  those  conditions  of  the  cortex,  produced  by  irritation, 
which  manifest  themselves  in  the  form  of  convulsions.  So 
great  a  prominence  did  syphilis  have  as  one  of  the  exciting 
causes  of  such  irritation  that  the  term  ''  Jacksonian  epilepsy  " 
is  now  often  used  as  synonymous  with  the  convulsions  met 
with  in  that  disease.  The  theory  which  this  author  advances 
to  explain  these  convulsive  attacks  is  as  follows  :  That  irrita- 
tion of  the  cortex  tends  toward  an  abnormal  accumulation  of 
nervous  energy,  so  that  the  affected  part  is  under  a  state  of 

'  "  St.  Bartholomew's  Hospital  Reports." 

2  "  Medico-Chir.  Trans." 

3  Op.  cit.     Also,  see  "  Medical  Times  and  Gazette,"  1 875. 


88  TEE  BRAIN.  ^^^^^H 

high  tension,  and,  under  certain  conditions,  this  irritated 
portion  discharges  itself  in  a  sudden  and  explosive  manner, 
thus  producing  a  subsequent  exhaustion  of  its  powers ; 
hence  a  convulsion,  and  often  some  type  of  monoplegia  fol- 
lowing it.  ^■ 

The  convulsions  dependent  upon  irritation  of  the  cortex 
may  assume  all  of  the  different  varieties  produced  by  de- 
structive lesions  of  the  motor  area,  and  may  even  result  in 
paralysis  ;  thus  the  leg  may  alone  be  affected  with  spasm,  the 
arm  alone,  the  arm  and  hand  together,  and  the  face  alone,  or 
in  connection  with  the  upper  extremity. 

It  may  often  assist  in  the  localization  of  a  lesion,  which  is 
creating  the  irritation  of  the  cortex,  to  note  carefully  the  ' 
muscles  affected  at  the  onset  of  the  convulsion.  Such  in- 
formation may  enable  the  observer  (through  a  knowledge  of 
the  motor  centers)  to  trace  the  seat  of  the  region  within  the  | 
cortex  which  first  exhibited  a  tendency  to  explosive  discharge 
of  its  nervous  energy.  Horsley  has  utilized  the  guides  so  af- 
forded in  trephining  successfully  for  cortical  cerebral  lesions.      , 

The  Sensory  Regions  of  the  Cerebrum. — A  part  of  the  ' 
parietal,  the  temporo- sphenoidal  and  occipital  lobes  are  now  i 
accepted  by  most  authors  as  the  portions  of  the  cerebral  cortex  | 
which  can  appreciate  the  perception  of  sensory  impressions,    .H 

The  experiments  of  Munk,  made  with  a  view  of  determin-     ■ 
ing  the  area  of  common  sensation  in  the  cerebral  cortex,  lead     \ 
to  the  conclusion  that  the  entire  parietal  cortex  must  be  de-     ; 
stroyed,  and  the  ascending  frontal  convolution  as  well,  beford'y^jj 
complete  and  permanent  anaesthesia  is  produced  on  the  oppo-     ; 
site  side  of  the  body  below  the  head.     These  results  make  the 
motor  area  overlap  the  sensory  area  to  some  extent,  and  tend     j 
to  refute  the  deductions  of  Ferrier,  who  places  the  center  ot^% 
tactile  sensations  in  the  temporal  lobe,  and  to  confirm  the-    ■ 
views  held  by  Luciani  and  Exner.     If  a  partial  destruction  of 
the  sensory  area  of  Munk  be  produced  in  animals,  the  an- 
aesthesia persists  only  for  a  few  weeks,  because  the  adjacent     ■ 
regions  learn  to  perform  vicariously  the  functions  of  the  part 
destroyed.  \ 


I 

SENSORY  AREAS  OF  CEREBRUM.  89 

Tripier,  of  Montpellier,  France,  has  lately  affirmed  the 
conclusions  o^  Munk,  respecting  the  existence  of  sensory- 
centers  in  the  central  convolutions,  as  has,  also,  Moeli,  of 
Berlin.  These  three  observers  support  the  view  that  the  motor 
and  sensory  centers  of  any  one  limh  coincide.  This  view- 
was  advanced  theoretically  by  Lnys  some  years  ago. 

Exner  has  collected  from  European  journals  all  cases  of 
cortical  disease  that  have  been  associated  with  disturbances 
of  sensation,  and  M.  Allen  Starr  has  lately  performed  the 
same  labor  in  American  literature.  An  analysis  of  the  cases 
so  collected  seems  to  justify  the  conclusions  of  Munk  and  his 
followers,  and  to  add  some  clinical  suggestions  of  value. 
These  cases  demonstrate  (1)  that  the  cerebral  cortex  of  each 
hemisphere  appreciates  sensory  impressions  from  both  sides 
of  the  body,  but  are  chiefly  associated  with  the  sensory  tracts 
of  the  opposite  lateral  half  of  the  body  ;  (2)  that  the  sensory 
area  includes  the  central  convolutions  (a  term  used  to  cover 
the  ascending  frontal  and  ascending  parietal  gyri — see  Fig. 
22)  and  the  posterior  part  of  the  parietal  lobe  ;  (3)  that  the 
sensory  centers  coincide  to  some  extent  with  the  motor  cen- 
ters of  similar  parts  ;  (4)  that  no  disturbances  of  general  sen- 
sation have  been  known  to  result  from  lesions  confined  to  the 
frontal,  temporo-sphenoidal,  or  occipital  lobes. 

It  has  been  determined,  with  some  approach  to  positive- 
ness  of  statement,  that  the  posterior  fibers  of  the  cms  are 
the  principal  means  of  transmission  of  sensory  impressions 
from  the  periphery  of  the  body  to  the  cerebrum,  and  the 
researches  of  Meynert  have  done  much  to  demonstrate  that 
these  fibers  are  connected  with  the  portions  of  the  cortex 
which  have  been  designated  as  the  regions  chiefly  associated 
with  sensory  perception. 

Buret,'  Veyssiere,"  and  Eaymond  have  shown  by  experi- 
ments that,  when  that  part  of  the  internal  capsule  which  is 
situated  between  the  lenticular  nucleus  and  the  optic  thala- 
mus is  divided,  a  loss  of  sensation  is  experienced  in  the  oppor 

1  Op.  cU.  2  u  gjjj.  I'h6inianesth6sie  de  cause  c6r6brale,"  1874. 


^^  hHB  ^^^  BRAIN. 

site  side  of  the  body,  but  that,  in  some  instances,  some  degree  m 
of  motor  paralysis  is  also  produced.  On  the  other  hand,  '^t 
these  same  observers  have  found  that  section  of  the  anterior 
two-thirds  of  the  internal  capsule  *  produces  a  distinct  motor 
paralysis,  with  no  effect  upon  the  function  of  sensory  percep- 
tion of  the  parts  paralyzed,  save  in  a  few  instances,  where 
such  a  result  of  a  fleeting  character  was  detected. 

These  deductions  are  fully  sustained  by  clinical  facts. 
The  collected  cases  reported  by  Charcot,"  Pitres,'  Turck,*  and 
many  others,  present  a  large  mass  of  evidence  to  warrant  the  i 
conclusion  that  lesions  of  the  posterior  part  of  the  internal 
capsule  are  indicated  by  hemi-ansesthesia  on  the  side  of  the 
body  opposite  to  the  lesion.  In  such  cases,  tactile  sensation 
is  destroyed  to  the  median  line  not  only  in  the  trunk,  but  also 
upon  the  face  ;  pain  and  the  sensation  of  heat  are  likewise 
abolished  ;  but  the  contractility  of  muscles  under  the  electric 
current  is  not  impaired  or  lost.  If  we  examine  the  mucous 
membranes  of  the  eye,  nose,  or  mouth,  the  same  condition  of  ^^ 
destroyed  sensibility  will  be  detected,  but  the  viscera  remain 
sensitive.  Furthermore,  taste,  smell,  and  hearing  are  some- 
times rendered  deficient,  and,  in  some  cases,  are  entirely  abol- 
ished, on  the  side  opposite  to  the  lesion  ;  and  the  special  sense 
of  sight  is  affected  in  a  variety  of  ways,  which  will  be  de-  .  ' 
scribed  in  detail.  ^- 

In  lesions  of  the  internal  capsule,  blindness  of  the  lateral  V ;, 
half  of  both  retmsd  (hemianopsia),  as  one  would  expect  ta 
find,  does  not  exist;  but,  on  the  contrary,  a  condition  of  ^^' 
amblyopia  occasionally  results,  which  is  characterized  by  a 
marked  contraction  of  the  field  of  vision,  and  especially  so  as 
regards  the  perception  of  color.  By  consulting  the  diagram 
given  you  in  the  description  of  optic  nerve,'  you  will  perceive 
that  the  field  for  blue  tints  is  the  largest,  and  that  red  is  next  ^    - 

'  Subsequent  pages  which  treat  of  the  internal  capsule  will  explain  the  situation  of  ^  ;  ^ 

the  different  bundles  which  compose  it.  * 

'  "  Lemons  sur  les  maladies  du  systSme  nerveux." 

'  "  L6sions  du  Centre  Ovale." 

*  See  Grassct,  "  Localizations  dans  les  maladies  c6r6brales,"  1878. 

*  See  page  of  this  volume  containing  a  diagram  by  Hirschberg. 


SENSORY  AREAS  OF  CEREBRUM.  91 

in  point  of  size,  while  green  comes  last. '  Now,  in  lesions  of 
the  internal  capsule,  the  perception  of  these  colors  is  apt  to 
be  impaired  in  the  relative  proportion  of  the  size  of  the  field, 
and  thus  green  may  be  entirely  lost,  while  the  vision  of  red 
or  blue  may  still  remain. 

It  has  been  shown  by  Landolt,"  who  has  done  much  to 
develop  this  special  field  of  investigation,  that  the  impair- 
ment of  vision  from  intra-cerebral  causes  is  not  altogether 
confined  to  one  side,  but  that  the  eye  upon  the  same  side  as 
the  lesion  is  somewhat  affected,  and  rendered  partially  an- 
aesthetic. 

Ifrwe  examine  the  eyes  so  affected,  we  can  not  discover 
by  the  ophthalmoscope  any  organic  disease  or  evidences  of 
degeneration  of  either  the  optic  nerve  or  the  retina,  provided 
that  the  examination  is  made  early,  before  any  late  results  of 
the  blind  condition  of  the  eye  manifest  themselves  as  the 
effect  of  disuse." 

As  has  been  before  stated,  the  condition  of  amblyopia  and 
the  absence  of  hemianopsia  are  in  opposition  to  what  the  ef- 
fects of  pressure  upon  the  optic  tracts  would  seem  to  suggest, 
but  we  still  have  a  clinical  fact  to  explain,  viz.,  that  hemi- 
anopsia does  sometimes  occur  with  attacks  of  hemiplegia. 
In  such, cases  as  these,  we  may  conclude  that  the  lesion  must 
be  so  situated  as  to  exert  its  influence  upon  the  motor  bun- 
dles of  the  brain  and  the  fibers  of  the  optic  tract  simultane- 
ously. The  occipital  cortex,*  which  is  now  regarded  by  most 
authorities  as  the  probable  center  of  vision,  does  not  seem  to 
exert  any  influence  upon  the  motor  apparatus,  as  is  shown 
by  its  destruction  in  animals. 

The  Occipital  Lobes  of  the  cerebrum  have  been  stated  to 
be  properly  included  among  the  sensory  regions  of  the  cortex. 

^  Violet  has  a  still  smaller  field,  but  it  is  not  shown  upon  the  chart, 

2  "  La  France  Medicale,"  Feb.  3,  1877. 

^  Any  intra-cranial  lesion  which  acts  in  such  a  way  as  to  inci'ease  the  intra-cranial 
pressure  may  produce  (in  addition  to  other  symptoms)  the  condition  known  as  "  choked 
disk,"  or  a  neuro-retinitis. 

^  The  reader  is  referred  to  the  lecture  on  the  optic  nerve  for  further  information  upon 
this  point. 


9g  TEE  BRAIK 

Experiments  of  section,  or  even  of  complete  removal  of  these^ 
lobes  of  one  or  both  sides,  however,  fail  to  show  any  effect  oh- 
general  sensation  or  motility.  Disturbances  of  sight*  have 
been  positively  produced  by  injuries  to  and  morbid  lesions  of 
the  occipital  convolutions.  The  distribution  of  the  fibers  of 
the  optic  tracts  to  the  cortex  of  the  occipital  lobes  (probably 
to  the  cuneus)  may  be  now  considered  as  positively  proved. 

It  is  claimed  by  Hughlings- Jackson  that  irritative  lesions 
of  the  occipital  lobes  give  rise  to  colored  perception  of  objects 
and  other  ocular  spectra,  and  he  further  states  that  such  evi- 
dences of  defective  perception  are  more  common  when  the 
lesion  affects  the  right  side. 

The  Temporo-sphenoidal  Lobes  are  in  relation  with  the 
bones  indicated  by  their  name,  and  lie  partly  on  the  base 
of  the  skull.  The  following  deductions  have  been  drawn, 
from  experimental  research,  as  to  the  special  functions  of 
this  lobe  and  some  of  the  adjacent  convolutions,  which  will 
require  separate  consideration : 

The  apparent  connection  of  this  region  with  the  special 
sense  of  vision  has  been  noticed  by  Hitzig,  Goltz,  and  McKen- 
drick,  the  two  former  of  whom  confine  their  experiments  to 
the  dog  species,  while  the  latter  operated  exclusively  upon 
pigeons.  Ferrier,'  however,  from  a  belief  that  other  functions 
could  be  demonstrated  as  pertaining  to  this  locality,  and  from 
disbelief  in  the  method  pursued  by  Goltz,'  as  adapted  to  the 
requirements  of  experimental  research  concerning  the  func- 
tions of  limited  areas  of  the  cortex,  made  a  series  of  experi- 
ments upon  the  brains  of  monkeys,  and  claims  to  have  estab- 
lished some  new  points  of  physiological  interest,  and,  possibly, 
of  practical  value  in  cerebral  localization. 

The  conclusions  which  were  drawn  as  the  results  of  the 
labors  of  this  learned  and  original  investigator  may  be  thus 
summarized : 

'  Munk  seems  to  have  positively  proved  an  association  of  the  occipital  lobe  with 
vision. 

«  Op.  cit. ;  Fcrrier  and  Yeo,  "  Brain,"  1880  ;  Exner,  "  Brain,"  October,  1880. 

'  That  of  trephining  over  the  spot  selected  for  investigation,  and  washing  away  the 
brain  by  a  forcible  stream  of  water. 


CORTEX  OF  TEMPORAL  LOBES.  93 

1.  In  the  angular  gyrus  ^  this  observer  thinks  that  in 
animals  there  is  situated  a  center,  which  causes,  on  electric 
irritation,  certain  movements  of  the  eyes^  pupils,  and  head, 
but  whose  destruction  creates  no  evidence  of  motor  paralysis 
in  the  muscles  of  either  the  eye,  its  lids,  or  the  pupil.  Uni- 
lateral destruction,  however,  of  this  center  causes  blindness 
of  the  opposite  eye,  which  proves  but  temporary  ;  while  the 
destruction  of  both  sides  causes  a  permanent  loss  of  sight 
in  both  eyes.'  It  would  thus  appear  (to  his  mind)  that  the 
center  of  either  side  is,  to  some  extent,  connected  with  both 
eyes. 

2.  In  the  superior  temporo- sphenoidal  convolution*  is 
found  to  exist  a  center  which,  under  galvanic  stimulation, 
creates  a  twitching  of  the  opposite  ear  and  an  apparent  modi- 
fication in  hearing  of  the  opposite  side,  which  it  was  found 
difficult  to  fully  locate  on  account  of  the  animal  not  being 
able  to  exhibit  appreciation  of  modification  of  that  special 
sense.  As  with  the  preceding  center,  destruction  of  this  con- 
volution, upon  one  side,  caused  some  abnormality  of  hear- 
ing ;  but,  when  both  sides  were  destroyed,  the  animal  became 
totally  deaf,  although  no  motor  paralysis  could  be  discovered 
in  either  case. 

3.  In  the  lower  extremity  of  the  lobe  previously  desig- 
nated, a  center  was  found  which  seemed  to  exert  an  influence 
upon  the  special  sense  of  smell,  and  also  to  create  motions  of 
the  nostril  and  head  which  indicated  excitation  of  that  sense. 
In  the  regions  adjacent  to  this  convolution  the  special  sense 
of  taste  became  affected  when  destroyed  ;  and,  when  the  con- 
volution and  the  adjacent  region  were  destroyed,  upon  both 
sides,  taste  and  smell  were  utterly  lost.  In  regard  to  these 
two  centers,  also,  unilateral  destruction  created  the  most 
marked  effects  upon  the  side  opposite  to  the  lesion,  while  a 
bilateral  destruction  abolished  the  sense  altogether. 

^  Regions  marked  13  in  Fig.  25  of  this  volume. 

2  The  experiments  of  Munk,  Luciani,  Tamburini,  Ferrier,  Yeo,  Dalton,  and  others, 
upon  these  centers  leave  the  field,  as  yet,  a  matter  for  further  investigation.  The  pre- 
ponderance of  testimony  goes  to  show  that  the  statement  of  Ferrier  is  not  true  of  man. 

*  See  diagrammatic  cut  on  page  79  of  this  volume ;  regions  marked  14. 
9 


94 


THE  BRAIK 


4.  In  the  region  of  the  hippocampus  some  evidence  was 
given  of  a  center  possessing  the  appreciation  of  tactile  sensa- 
tion, but  the  situation  of  the  part  rendered  experiment  upon 
it  difficult,  and  somewhat  less  positive  than  that  upon  the 
areas  previously  discussed. 


Fig.  27. — A  diagram  illustrating  the  course  of  nerve  impulses  in  the  cerebrum, 

(After  Dodds.) 

A,  the  motor  regions  of  the  cerebral  cortex,  represented  by  arrow-heads ;  B,  the  sensory 
regions  of  the  cerebral  cortex,  represented  by  circles ;  C,  commissural  fibers,  con- 
necting the  two  regions  of  the  cortex  (probable,  but  not  positively  demonstrated); 

D,  sensory  nerve  fibers^  the  arrow  showing  the  centripetal  direction  of  the  impulse ; 

E,  motor  nerve  fibers^  the  arrow  showing  the  centrifugal  direction  of  the  impulse; 
C  S,  ^^ corpus  striatum^''  (the  probable  motor  ganglion  at  the  base  of  the  cerebrum); 
0  T,  '^ optic  thalamus^^  (the  probable  sensory  ganglion  at  the  base  of  the  cerebrum); 
1,  a  few  sensory  fibers,  possibly  connected  with  the  "corpus  striatum";  2,  a  few 
motor  fibers,  possibly  connected  with  the  "optic  thalamus." 


m 


It  is  to  be  regretted  that  the  conclusions  of  this  brilliant  \ 
investigator  as  to  the  situation  of  these  special  centers  in  the  ' 
sensory  regions  of  the  cerebrum  are  not  as  positively  sustained  I 
by  clinical  and  pathological  facts  as  were  his  conclusions  ! 
drawn  from  experimental  research  upon  the  motor  area  of  the  ! 
brain  of  the  monkey  tribe.  Ferrier  endeavors  to  explain  the  \ 
discrepancy  between  the  facts  obtained  by  experiment  and  '  '. 
those  afforded  by  disease  of  the  same  regions  in  the  human  ^Mi 
brain,  by  the  hypothesis  that  the  special  senses  may  be  gov-  '  ;^i 


CORTICAL  LESIONS   OF  CEREBRUM,  95 

erned  by  a  Mlateral  rather  than  a  unilateral  impulse,  as  the 
experimental  facts  pertaining  to  the  special  senses  of  sight 
and  hearing  seem  to  warrant.  This  has  not,  as  yet,  been  dis- 
proved, since  all  of  the  cases  recorded  have  been  of  a  unilat- 
eral character. 

To  what  extent  these  physiological  subdivisions  of  the 
sensory  area  of  the  cerebrum  may  be  regarded  as  of  practical 
utility  in  diagnosis  can  hardly  yet  be  determined,  as  the  field 
is  still  a  new  one,  and  the  collection  of  clinical  and  patholog- 
ical records  is  hardly  sufficient  for  a  basis  of  positive  deduc- 
tion respecting  many  points  yet  in  dispute. 

The  contents  of  the  preceding  pages  will  probably  enable 
the  reader  to  appreciate  the  grounds  which  justify  the  follow- 
ing conclusions  respecting  the  diagnosis  of  focal  lesions  of  the 
cerebral  cortex. 

A  SUMMARY   OF  THE    EFFECTS    OF  CORTICAL  LESIONS   OF  THE 

CEREBRUM. 

Lesions  of  the  motor  convolutions,  when  of  small  size,  pro- 
duce some  form  of  monoplegia^  and  possibly  a  coexisting 
mono-ansesthesia  with  a  loss  of  muscular  sense  in  the  part ; 
when  of  large  size,  k  hemiplegia  may  be  produced. 

Consciousness  is  not  necessarily  lost  at  the  time  of  the 
attack. 

Early  rigidity  of  the  paralyzed  muscles  is  often  present. 

Cortical  hemiancBsthesia  will  be  produced  when  the  entire 
parietal  cortex  is  involved  by  a  cortical  lesion,  and,  in  addi- 
tion, the  balance  also  of  the  motor  area,  which  lies  outside  of 
the  parietal  lobe.  Such  an  extensive  cortical  lesion  is  rare- 
ly, if  ever,  encountered.  We,  therefore,  do  not  observe  co- 
existing hemiplegia  and  complete  hemiansesthesia  in  cortical 
disease. 

Localized  pain  in  the  head  is  a  symptom  which  is  often 
present  in  connection  with  cortical  lesions.  If  it  be  absent, 
percussion  over  the  lesion  will  generally  tend  to  excite.  This 
step  will  also  tend  to  increase  the  pain,  in  many  cases,  when 
it  exists  prior  to  this  test. 


96  THE  BRATN. 

Convulsions^  when  followed  by  transient  attacks  of  pa- 
ralysis (Jacksoniau  epilepsy),  indicate  an  irritative  lesion  of 
the  cortex.  They  are  frequently  encountered  in  connection 
with  syphilitic  disease  of  the  brain.  Subjective  sensations 
(parsesthesise)  may  also  be  excited  in  limited  portions  of  the  , 
limbs.  ^•^.' 

Blindness  of  that  half  of  each  retina  which  corresponds 
to  the  cerebral  hemisphere  affected,  occurs  when  extensive 
cortical  disease  of  the  occipital  lobe  (chiefly  of  the  cuneus)  is 
present.  "  Word-hlindness  "  may  also  be  produced  by  lesions 
of  these  lobes  (especially  if  upon  the  left  side).  ' . . 

Lesions  of  the  first  temporal  convolution  (chiefly  upon  the 
left  side)  may  produce  abolition  of  hearing^  and  also  the  con- 
dition known  as  ^'word-deafness "  (see  page  97). 

Lesions  of  the  tip  of  the  temporal  lobe  may  be  the  cause 
of  abolition  of  the  sense  of  smelly  or  of  taste.  The  memories 
of  taste-and-smell-perceptions  may  also  be  impaired  or  lost. 

Ataxic  aphasia  and  paraphasia  may  be  developed  as  a 
result  of  cortical  lesions,  which  involve  respectively  the 
speech  center  of  Broca  and  the  'island  of  Reil." 

The  face  is  never  rendered  totally  hemiplegic  by  cortical 
lesions.  The  conditions  known  as  ''  mono-ancesthesia^'^''  by 
which  we  mean  an  impairment  or  total  arrest  of  sensation  in 
some  distinctly  localized  part,  as,  for  example,  the  hand,  arm, 
leg,  etc.,  and  also  the  condition  known  as  '''  mono-par (zsthesia^'' 
which  signifies  the  existence  of  subjective  sensations  of  a  defi- 
nitely localized  character,  are  particularly  diagnostic  of  corti- 
cal lesions  lying  posterior  to  the  fissure  of  Rolando.  The 
former  indicates  a  destructive  lesion,  the  latter  an  irritating 
lesion. 

The  muscular  sense  is  liable  to  be  impaired  (when  a  corti- 
cal lesion  of  the  motor  area  exists)  in  the  parts  functionally 
associated  with  the  limits  of  il^ie.  part  diseased. 

Monoplegia  and  monospasm  seem  to  be  peculiarly  diag- 
nostic of  a  cortical  disease  anterior  to  the  fissure  of  Rolando; 
although  Horsley's  late  observations  show  that  this  is  not 
always  the  case. 


CORTICAL  LESION'S  OF  CEREBRUM.  97 

The  memories  of  sensory  ionpressions  are  more  frequently- 
impaired  by  cortical  lesions  of  the  left  hemisphere  than  of  the 
right  (as  shown,  for  example,  in  ataxic  aphasia,  word -blind- 
ness, word-deafness,  paraphasia,  etc.). 

Motor  memories  may  be  impaired  by  cortical  disease  af- 
fecting the  motor  area.  Subjects  may  thus  lose  a  dexterity 
with  the  fingers,  arm,  hand,  leg,  etc.,  which  they  had  acquired 
previous  to  the  development  of  the  lesion.  A  knowledge  of 
this  fact  may  sometimes  aid  in  the  localization  of  a  lesion. 

Irritative  lesions  of  the  cortex  of  the  cuneus  (a  part  of  the 
occipital  lobe)  may  cause  hallucinations  of  vision.  If  one 
hemisphere  only  is  affected,  the  objects  seen  will  appear  to 
lie  on  the  side  opposed  to  the  lesion,  and  to  move  with  the 
eyes  as  they  are  turned  from  side  to  side. 

Lesions  of  the  ^'island  of  Beil^^^  or  '^ insula^^  of  the  left 
side  (Fig.  23),  seem  to  create  (in  some  instances)  symptoms  of 
ataxic  aphasia,  and  also  paraphasia  (the  substitution  of 
wrong  words).  The  motility  of  the  face  and  arm  of  the  op- 
posed side  may  occasionally  be  impaired  from  cortical  lesions 
of  this  region. 

Lesions  of  the  cortex  confined  to  the  apex  of  the  temporal 
lohe  (Fig.  26)  are  liable  to  cause  an  impairment  of  the  sense 
of  smell  or  of  taste  (if  destructive  in  character)  or  subjective 
odors  and  tastes  (if  irritative  in  character). 

Destructive  lesions  of  the  cortex  of  the  motor  convolu- 
tions (Fig.  26)  is  followed  by  a  descending  degeneration  of 
the  fibers  which  arise  from  these  gyri.  This  may  account  (?) 
for  the  late  rigidity  of  the  muscles  paralyzed,  which  is  occa- 
sionally observed  after  such  lesions. 

Cortical  lesions  of  the  base  of  the  brain  are  especially  liable 
to  produce  vomiting,  choked  disk,  bilateral  paralysis,  and 
symptoms  of  impairment  of  some  of  the  cranial  nerve  trunks. 
The  crus,  pons,  and  ''island  of  Reil"  may  also  be  involved 
and  give  additional  symptoms. 

Cortical  disease  of  those  frontal  gyri  which  lie  anteriorly 
to  the  motor  centers  (Fig.  26)  is  often  attended  with  no  symp- 
toms of  a  diagnostic  character.     The  higher  mental  faculties 


98  ^^^*  THE  BRAIK 

may  occasionally  give  signs  of  more  or  less  impairment.  Con- 
nected thought,  the  control  of  the  emotions,  and  concentra- 
tion of  the  attention  are  particularly  difficult  under  such  cir- 
cumstances. 

The  memories  of  sound  or  sight  impressions,  as  well  as 
those  of  smell,  taste,  muscular  movements,  etc.,  may  be  sepa- 
rately annihilated  by  cortical  disease.  Cases  of  this  charac- 
ter have  been  discussed  under  the  head  of  Aphasia  (see  pages 
73  to  76  inclusive). 

SUMMARY  OF  THE  PHYSIOLOGY  OF  THE  CEREBRAL  CORTEX. 

From  the  statements  made  in  previous  pages,  we  may 
summarize  the  functions  of  the  cortex  (the  gray  matter  of 
the  cerebral  convolutions),  as  well  as  the  symptoms  which 
can  be  attributed  to  disease  confined  to  that  region,  as  fol- 
lows : 

1.  Contrary  to  old  statements,  the  cortex  is  capable  of 
artificial  stimulation.  The  functions  of  certain  cortical  areas 
have  thus  been  determined  with  an  approach  to  accuracy.* 

2.  A  well-defined  relationship  exists  in  man  as  well  as  in 
animals  between  the  limited  areas  of  the  cortex  and  certain 
muscular  groups.  This  has  been  confirmed  by  pathological 
and  clinical  observation,  and  also  by  experiments  made  upon 
the  human  subject  by  Dr.  Amidon,  of  this  city.'    The  accu- 

'  There  arc  at  the  present  time  three  distinct  schools  among  the  experimental  physi- 
ologists respecting  the  subject  of  cerebral  localization.  Ferricr  and  Munk  represent  a 
faction  which  strenuously  hold  the  view  that  the  cortical  gray  substance  can  be  mapped 
out  into  areas  whose  limits  are  clearly  defined,  as  well  as  their  individual  functions. 
Goltz  stands  at  the  head  of  a  school  which  denies  the  accuracy  of  these  views,  and  sup- 
ports the  conclusion,  originally  advanced  by  Flourens,  that  the  brain  can  only  act  as  a 
whole.  Exner  and  Luciani  (in  common  with  their  followers)  occupy  a  ground  which  op- 
poses very  sharply-defined  boundaries  to  cortical  areas,  functionally  associated  with  the 
various  senses.  They  believe  that  these  areas  overlap  each  other  to  a  greater  or  less 
extent.  At  present,  the  latter  view  seems  to  be  most  perfectly  in  accord  with  clinical  and 
pathological  data. 

«  Prize  Essay  of  1880,  "Archives  of  Medicine,"  April,  1880. 

"  Dr.  Amidon's  experiments  in  cerebral  localization  are  based  on  the  following  propo- 
sitions: 1.  Marked  local  variations  in  the  temperature  of  the  cephalic  contents  can  be 
demonstrated  by  surface  thermometers.  2.  Cerebral  cortical  localization  is  now  so  far 
advanced  as  to  warrant  the  assertion  that  the  psycho-motor  centers  for  one  half  the  body 
occupy  a  certain  area  iu  the  cerebral  cortex  of  the  opposite  hemisphere.     3.  Functional 


EXCITABLE  REGION'S  OF  CORTEX,  99 

racy  of  Dr.  Amidon^s  observations  has  been  called  into  ques- 
tion by  other  experimenters  since  their  publication  ;  but  I  am 
inclined  to  doubt  the  justness  of  the  criticism.  The  counter- 
experiments  seem  to  me  to  be  defective  in  the  methods  em- 
ployed. Dr.  Amidon  has  lately  published  some  additional 
proofs  of  the  ability  of  the  cranial  bones  to  transmit  heat.  ^ 

Dr.  M.  Allen  Starr  has  collected,  of  late,  all  the  cases  re- 
ported in  American  literature  which  support  the  modern 
views  of  cerebral  localization.'  These  supplement  similar 
cases  collected  by  Ferrier,  Charcot,  Wernicke,  Nothnagel, 
and  others  from  the  European  journals. 

3.  The  excitable  region  of  the  cortex,  where  motor  effects 
are  chiefly  produced,  may  be  stated  to  be  localized  in  the 
following  parts :  The  ascending  frontal  convolution  ;  the  base 
of  the  first  frontal  convolution ;  the  second  frontal  convolu- 
tion ;  the  third  frontal  convolution ;  the  ascending  parietal 
convolution ;  the  superior  parietal  convolution ;  the  supra- 
marginal  gyrus ;  and  the  para-central  lobule.  Nov/,  let  us 
see  what  centers  pertain  to  each  of  these  convolutions,  accord- 
ing to  the  researches  of  Ferrier : 

The  center  for  movements  of  the  lips  and  tongue  (the  motor 
speech  center)  lies  at  the  base  of  the  third  frontal  con- 
volution, near  the  fissure  of  Sylvius.  (See  9,  10,  in 
Fig.  26.) 

activity  of  an  organ  implies  increased  blood  supply  and  tissue  change,  and  consequent 
elevation  of  the  temperature  of  that  organ.  4.  Willed  contraction  of  muscles  presupposes 
an  increased  activity  of  the  volitional  motor  center  of  those  muscles  in  the  cerebral  cor- 
tex. From  this  it  was  natural  to  make  the  deduction  that  voluntary  activity  in  a  periph- 
eral part  would  cause  a  rise  of  temperature  in  the  psycho-motor  center  for  that  part,  which 
might  be  indicated  by  external  cerebral  thermometers. 

*'  Seguin's  self -registering  surface  thermometers  were  used,  numbers  of  which  were 
applied  to  the  surface  to  be  tested  by  passing  them  through  holes  in  rubber  straps  se- 
cured to  the  head  by  buckles.  The  desirable  points  in  the  subject  experimented  on  are, 
a  well-shaped  head,  thin  hair,  well-developed  and  trained  muscles,  power  of  facial  expres- 
sion, especially  of  unilateral  facial  movements  and  the  ability  to  contract  individuf^l  mas- 
cles,  and  moderate  intelligence.  A  man  is  preferable  to  a  vvomaTX,  sild  aJEu'ropeaiZto  ai; 
African.  The  mode  of  performing  and  recording  cxpenmenxs  and  tne  liabilities  io  error  ^ 
are  all  fully  described."  (Report  in  "  Xew  York  :MVd:  .Tour^,"  October,  1§80.)  ^  ;  ;  ; '  \  ; 
^  "Facts  and  Figures  in  Cerebral  Thermometry."  ,  ,-,  O^  »  '^"^  r  .  ;  :  'r'  ' 
""  "  Cortical  Lesions  of  the  Brain,"  "  Am.,  Jo«'r.  ^Q^.  B?i.,"  JuV*  ^^S^' 


100  ^         TEEBRAlW. 

Upon  the  first  and  second  frontal  convolutions  lie  found  a 
center  (see  12  in  Fig.  26):  (1)  For  lateral  movements 
of  the  head;  (2)  for  elevation  of  the  eyelids ;  and  (3)  for 
dilatation  of  the  pupil. 

The  ascending  frontal  convolution  presents,  from  below  up- 
ward, the  following  centers:  For  elevation  and  depres- 
sion of  the  corners  of  the  mouth  (8  and  7) ;  for  move- 
ments of  the  forearm  and  the  hand  (6) ;  for  extension 
and  the  forward  movement  of  the  hand  and  the  arm  (6) ; 
centers  for  complex  movements  of  the  arms  and  legs^ 
when  acting  together  (2,  3,  and  4). 

The  ascending  parietal  convolution  presents,  from  above 
downward,  four  centers  for  complex  movements  of  the 
hand  and  wrist  (a,  &,  c,  d\  such  as  the  use  of  individual 
fingers,  prehensile  movements,  etc.  At  its  most  superior 
portion,  the  centers  (2,  3,  and  4),  which  control  the  alter- 
nating movements  of  the  arm  and  leg,  as  in  the  act  of 
swimming,  seem  to  overlap  the  ascending  parietal  convo- 
lution ;  but  they  are  not  definitely  placed. 

The  superior  parietal  convolution  presents  the  center  which 
presides  over  the  movements  of  the  leg  and  foot  ^  as  in  the 
act  of  walking. 

When  we  discuss  the  subject  of  cerebral  surgery,  reference 
will  be  made  to  modifications  of  the  views  of  Ferrier  relative 
to  the  motor  centers. 

4.  The  sensory  region  of  the  cortex  is  confined  to  the  pa- 
rietal, temporal,  and  occipital  lobes  of  the  cerebrum.  In  it 
certain  centers  have  been  definitely  located  by  Ferrier,  which 
are  not,  as  yet,  accepted  as  fully  proven,  but  many  of  which 
are  now  considered  as  supported  rather  than  confuted  by 
clinical  and  physiological  evidence. 

,  T^e  angular  gyrus  is  said  by  this  author  (erroneously,  I 

f  /     'think)  to- eon  tain  the  centers  for  vision  (13, 13,  in  Fig.  26), 

.    ,    while  mdvwent^fof  ;the  eyes  also  are  produced  when 

tkesfe«)JegiQns  are  stimulated.'     Later  research  seems  to 

' '  Bxpe^hp^^ntaof  Ferrier,  Yeo,  Dalton,  and  others. 


CORTICAL  AREA  FOR  TACTILE  SENSATIONS.  101 

warrant  the  conclusion  that  the  occipital  lobes  are  alone 
associated  with  vision. 

The  superior  temporo-sphenoidal  convolution  may  be  regard- 
ed, in  the  light  of  existing  information,  as  the  seat  of  the 
centers  of  hearing  (14,  14, 14,  in  Fig.  26).  The  head  and 
eyes  are  caused  to  move  toward  the  opposite  side,  and 
the  pupils  to  dilate  largely,  according  to  Ferrier,  by  ex- 
citation of  this  convolution. 

The  centers  of  smell  are  now  believed  to  lie  in  the  region  of 
the  tip  of  the  temporo-sphenoidal  lobe  (the  so-called  *^su- 
biculum  cornu  Ammonis"). 

The  conscious  appreciation  of  tactile  sensations  is  now  at- 
tributed to  the  cortical  gray  matter  of  those  parietal  con- 
volutions which  are  not  included  in  the  so-called  "motor 
area"  of  the  cerebrum.  This  view  has  been  lately  con- 
firmed by  the  researches  of  Flechsig,  and  is  in  accord 
with  pathological  facts  lately  brought  to  professional 
notice.  The  view  that  the  cortical  fields  of  motion  and 
general  sensation  overlap  each  other  to  some  extent  is 
fast  gaining  ground — the  sensory  area  is  thought  to  ex- 
tend over  the  entire  parietal  lobe,  while  the  motor  area 
does  not  pass  beyond  the  ascending  parietal  gyrus.  In  the 
upper  third  of  these  regions  tactile  sensations  from  the 
leg  (chiefly  the  opposite  member)  are  probably  perceived. 
Those  from  the  upper  extremity  are  transmitted  to  the  mid- 
dle third  of  the  same  field  ;  each  hemisphere  being  con- 
nected with  both  sides,  but  chiefly  with  the  opposed  limb. 

5.  The  collection  of  reported  cases  of  tumors,  clots,  soften- 
ings, pressure  effects  (from  exostoses,  meningeal  exudations, 
or  thickenings),  etc.,  seems  to  confer,  to  a  greater  or  less  ex- 
tent, the  effects  of  physiological  experiment  or  faradization, 
and  the  following  general  statements  as  to  the  results  of 
lesions  of  the  cortex  can  be  safely  used  as  possessing  practical 
value  at  the  bedside : 

{a)  When  the  faculty  of  speech  is  affected,  on  account  of  an 
inability  to  properly  coordinate  the  movements  of  the 


102  TEE  BRAm. 

tongue,  lips,  and  palate,  it  is  safe  to  conclude  that  the 
lesion  involves  one  of  three  situations,  viz.  :  the  anterior 
convolutions  of  the  "  island  of  Reil,"  the  base  of  the  third 
frontal  convolution,  or  the  white  substance  lying  between 
the  third  frontal  convolution  and  the  base  of  the  cere- 
brum. The  lesion,  being  most  frequently  met  with  upon 
the  left  side  of  the  brain,  will  usually  be  associated  with 
some  form  of  paralysis  affecting  the  right  side  of  the 
body ;  but  the  faculty  of  speech  may  be  aifected  by 
lesions  of  the  right  side  as  well  as  those  of  the  left  side, 
as  proven  by  the  cases  collected  by  Seguin  and  others. 

{h)  Paralysis  of  motion  affecting  the  upper  extremity^  either 
entirely  or  to  a  greater  extent  than  other  parts  involved,' 
suggests  a  lesion  which  is  situated  on  the  side  opposite  to 
the  paralysis ;  and  either  confined  to,  or  involving,  the 
ascending  convolutions  of  the  frontal  or  parietal  lobes. 

{c)  When  the  facial  muscles  are  prominently  affected,  I  am 
inclined  to  think  the  lesion  may  be  located  in  the  frontal 
lobe,  anterior  to  or  in  the  vicinity  of  the  pre-central  fis- 
sure or  sulcus ^^  or  in  the  lower  third  of  the  ascending 
parietal  convolution. 

{d)  When  the  muscles  of  the  leg^  are  exclusively  affected  (and 
the  probability  of  spinal  lesions  involving  only  the  lateral 
half  of  the  spinal  cord  can  be  excluded),  or  when  the  leg 
muscles,  in  an  attack  of  hemiplegia  of  clear  cranial  ori- 
gin, show  special  impairment,  the  lesion  can  be  probably 
placed  at  the  upper  end  of  the  fissure  of  Rolando^  affect- 
ing the  ascending  convolutions  of  the  frontal  or  parietal 
lobes.  The  views  of  Horsley  (page  96)  have  already  been 
discussed. 

(e)  Lesions  of  the  sensory  area  of  the  cerebral  cortex  are 
not  as  well  understood  in  their  clinical  aspects  as  those 
of  the  motor  area,  since  less  opportunity  has  been  afforded 

'  See  the  peculiar  types  of  brachial  monoplegia  and  the  views  of  Horstey,  as  described 
on  pages  82  and  83  of  this  volume. 

*  It  may  not  be  confined  alone  to  this  region,  since  the  various  forms  of  brachial 
monoplegia  arc  often  associated  with  facial  paralysis.      See  views  of  Ilorsley  on  page  83. 

'  See  the  types  of  crural  monoplegia,  described  on  pages  84  and  85  of  this  volume. 


SENSORY  REGIONS  OF  CORTEX.  103 

for  the  pathological  study  of  this  type  of  cases,  but  many 
facts  relating  to  them  have  been  already  stated.  The 
reader  is  referred  to  pages  88  and  89  for  information. 

(/)  All  of  the  symptoms  produced  by  lesions  of  the  cortex 
may  be  the  result  either  of  actual  destruction  of  the  nerve 
tissue  of  the  cortex,  or  evidences  of  irritation  of  the  cor- 
tex. The  symptoms  will  differ  in  the  two  cases,  so  as  to 
often  assist  the  diagnostician. 

ig)  Lesions  of  the  cortex,  if  outside  of  the  motor  area^  and 
involving  the  dura  mater,  may  be  manifested  by  convul- 
sions, and,  possibly,  by  headache.  These  convulsions, 
and  the  headache  which  may  be  produced,  are  respective 
evidences  of  irritation  of  some  portion  of  the  motor  area 
of  the  cortex,  or  of  adjoining  sensory  areas. 

{h)  The  sensory  areas  of  the  cerebral  cortex  comprise  those   • 
of  general  sensation   (pain,   touch,   temperature)  in  the 
parietal  lobes  ;  those  of  sight  in  the  occipital  lobes  ;  and 
those  of  hearing,  smell,  and  taste  in  the  temporo-sphe- 
noidal  lobes. 

{i)  The  symptoms  which  prominently  indicate  irritation  of 
the  motor  cortex  are  conmdsions,  which  are  often  fol- 
lowed by  paralysis.  This  paralysis  may  be  either  of  the 
transient  or  permanent  variety,  although  the  former  is 
the  more  common.  The  groups  of  muscles  which  are 
prominently  affected  in  the  convulsive  attacks  may  afford 
the  physician  a  guide  to  the  seat  of  the  irritation,  since 
the  same  centers  are  probably  affected,  as  if  the  corre- 
sponding muscles  were  paralyzed,  rather  than  convulsed. 

{j )  The  destructive  lesions  of  the  gray  matter  of  the  cerebral 
convolutions,  if  limited  to  the  motor  area,  produce  pe- 
ripheral paralysis  of  the  parts  governed  by  the  centers 
which  are  involved,  chiefly  on  the  side  of  the  body  oppo- 
site to  the  situation  of  the  seat  of  disease.  Thus  em- 
bolism, by  plugging  the  middle  cerebral  artery,  shuts  off 
the  blood  supply  to  the  center  of  Broca,  and  aphasia  of 
the  motor  or  ataxic  variety  will  usually  be  produced  ; 
with  an  accompanying  hemiplegia  of  the  side  opposite  to 


lOi  THE  BRAm. 

the  embolus,  in  case  the  blood  supply  is  impaired  to 
other  parts  of  the  motor  area.  A  destructive  lesion  of 
the  motor  region,  if  not  due  to  embolism,  is  liable  to  pro- 
duce hemiplegia,  without  aphasia,  on  the  opposite  side 
to  the  seat  of  disease.  Paralysis  of  motion  exists  to  a 
greater  or  less  extent  when  the  motor  area  of  the  cortex 
is  affected  in  any  part. 

{Jc)  When  the  paralyzed  muscles  become  rigid,  after  an  at- 
tack of  hemiplegia,  from  destructive  lesions  of  the  motor 
area  of  the  cortex,^t  may  be  considered  as  an  evidence  of 
a  secondary  degeneration  of  the  nerve  fibers,  which  is 
progressing  downward  along  the  spinal  cord.  This  is 
prominently  developed  when  the  para-central  lobule  is 
the  seat  of  disease,  but  it  exists  to  a  greater  or  less  ex- 
tent when  the  motor  area  of  the  cortex  is  affected  in 
any  part. 

(Z)  We  have  clinical  evidence  of  the  fact  that  memories  of 
various  kinds  are  stored  within  the  cells  of  the  cortical 
gray  matter  of  the  cerebrum,  and  we  are  led  to  the  con- 
clusion that  each  particular  gyrus  acts  as  a  receptacle  for 
memories  of  such  impressions  as  it  is  capable  of  receiv- 
ing. We  have  reason  to  believe  that  the  occipital  lobes 
appreciate  visual  sensations  and  also  accumulate  sight 
memories  ;  that  the  superior  temporal  convolution  ap- 
preciates sound  impressions  and  retains,  furthermore, 
all  memories  of  sound  ;  that  the  motor  area  of  the  cere- 
bral cortex  has  the  power  of  storing  memories  of  mus- 
cular acts,  which  are  totally  distinct  from  all  other  forms 
of  memories  ;  that  smell  memories  are  retained  by  the 
cells  in  the  tip  of  the  temporo-sphenoidal  lobes,  which 
give  to  us  our  conscious  appreciation  of  odor ;  and  that 
memories  of  tactile  sensations,  as  well  as  those  of  pain 
and  temperature,  are  probably  connected  with  the  cells 
of  the  parietal  convolutions,  which  lie  posterior  to  the 
motor  gyri.  These  facts  enable  us  to  draw  clinical  de- 
ductions of  value  respecting  those  remarkable  cases  of 
word-deafness  and  word-blindness  which  have  been  re- 


DIFFUSED   CORTICAL  LESIONS.  105 

ported  from  time  to  time.  The  inability  to  recognize 
the  meaning  of  spoken  words  would  indicate  an  impair- 
ment of  the  memories  of  sound  ;  hence  a  lesion  of  the 
superior  parietal  convolution,  in  which  such  memories 
are  stored.  An  inability  to  recognize  written  or  printed 
language  would  indicate  a  loss  of  sight  memories,  and 
would  therefore  point  toward  a  lesion  of  the  occipital 
cortex.  Dr.  Starr  has  collected  some  very  interesting 
cases  that  bear  upon  this  field,  and  has  also  contributed 
a  popular  article  upon  the  mechanism  of  memory  to  one 
of  our  monthly  magazines.' 

{m)  In  those  cases  where  the  lesions  are  diffused  over  a  large 
surface  of  the  cortex  (as  in  the  exudation  of  acute  menin- 
gitis, suppuration  between  the  bone  and  the  dura  mater, 
etc.),  delirium^  convulsions,  and  local  pain  are  often 
present,  and  may  properly  be  regarded  as  evidences  of 
the  excessive  irritation  which  exists  in  consequence  of  the 
pressure  and  hypersemia.  Coma  and  paralysis  may  fol- 
low ;  in  which  case  they  are  to  be  attributed,  either  to  the 
local  anaemia  produced  by  the  pressure  (thus  causing  im- 
pairment of  nutrition  to  the  subjacent  cortex),  or  to 
circulatory  changes  and  increased  tension  of  the  entire 
brain. 

{n)  The  affection  called  "diffuse  meningo- encephalitis "  or 
the  "general  paralysis  of  the  insane"  is  so  commonly 
met  with,  and  affords  such  striking  evidences  of  the  ef- 
fects of  general  pressure  upon  and  irritation  of  the  cere- 
bral cortex,  that  its  symptoms  have  to  the  neurologist 
more  than  a  clinical  interest.  From  a  careful  study  of 
such  cases,  we  learn  that  the  symptoms  first  manifested 
are  contractions  of  special  fibers  in  the  muscles  of  the 
face,  tongue,  and  limbs,  and  that  the  speech  becomes 
tremulous  and  the  articulation  spasmodic.  Later  on, 
acute  delirium  and  impairment  of  memory  and  judgment 
appear,  and  a  state  of  the  muscles  of  the  limbs  develops 

1  "  Popular  Science  Monthly,"  September,  1884. 


106  THE  BRAIN. 

which  may  be  one  either  of  semi- paralysis  or  of  semi- 
ataxia.  In  the  final  stages,  the  mental  faculties  become 
abolished  ;  a  state  of  insanity,  characterized  by  periods 
of  delirium,  is  produced ;  and  the  patient  dies  without 
any  apparent  changes  in  the  ordinary  organic  functions 
of  the  body. 

A  prominent  author,  when  referring  to  this  subject, 
says:  "A  person  who  exhibits  tremors  of  the  facial  mus- 
cles, of  the  tongue,  and  hand,  a  vibratory  and  slurred 
speech,  angular  or  tremulous  handwriting,  and  irregu- 
lar, small  pupils,  should  be  suspected  of  having  chronic 
peri- encephalitis  or  paralytic  dementia.  The  addition  of 
a  gradual  failure  of  mind — true  dementia — makes  the 
diagnosis  certain."*  In  case  there  should  be  added  to 
these  above-named  symptoms  exalted  notions,  with  ma- 
niacal attacks  and  epileptiform  seizures,  the  case  deserves 
the  name  of  "general  paresis" ;  and  as  such  the  form  is 
more  usually  seen  and  studied  by  asylum  physicians. 

WEIGHT  OF  THE  BRAIN  AND   OF  ITS   COMPONENT  PARTS. 

The  shape  of  the  cranium  may  be  employed  to  estimate 
the  relative  development  of  different  parts  of  the  encepha- 
lon ;  and  the  circumference  of  the  head  and  the  height  of 
the  skull  above  the  orifice  of  the  ear  may  also  approximately 
indicate  the  measurements  of  the  cerebrum. 

The  variations  in  the  skulls  of  the  different  nations  indi- 
cate an  amount  of  brain  which  is  in  the  direct  ratio  to  the 
facial  angle  of  Camper."  The  average  weight  of  the  brain  of 
a  healthy  adult  of  the  Caucasian  race  has  been  given,  by  most 
of  the  prominent  investigators  upon  this  subject,  as  about 
fifty  ounces  in  the  male,  and  some  six  ounces  less  in  the 
female.'  In  the  new-bom  infant,  the  weight  of  the  brain, 
in  the  two  sexes,  is  more  nearly  alike,  being  in  the  region 

>  E.  C.  Seguin,  "Med.  Record,"  1881. 

'  See  article  by  the  author  on  the  "Osteology  of  the  Head,"  "  Medical  Record,"  Octo- 
ber 16,  1880. 

•  See  researches  of  Reid,  Tiedmann,  Sims,  and  Quain. 


GROWTH  OF  THE  BRAIN. 


lor 


of  eleven  ounces  for  the  male  child  and  ten  ounces  for  the 
female. 

The  rapidity  of  growth  of  the  brain  is  not  uniform 
throughout  the  different  periods  of  life.  It  grows  very  rap- 
idly until  the  age  of  seven  years  ;  then  less  rapidly  until 
the  age  of  forty  is  reached,  when  it  attains  its  full  develop- 
ment ;  after  that  age  it  decreases  in  weight  about  one  ounce 
for  every  period  of  ten  years. 


Fig.  28. — Inferior  aspect  of  the  encephalon.     (After  Hirschfeld.) 

1, 1,  antei'ior  lobe  of  the  cerebrum;  2,  sphenoidal  portion  of  the  posterior  lobe;  3,  3,  oc- 
cipital portion  of  the  same  lobe  ;  4,  anterior  extremity  of  the  median  fissure  ;  5,  pos- 
terior extremity  of  the  same ;  6,  6,  fissure  of  Sylvius ;  7,  anterior  perforated  space ; 
8,  tuber  cinereum  and  pituitary  body ;  9,  corpora  albicantia ;  10,  interpeduncular 
space  (posterior  perforated  space);  11,  crura  cerebri;  12,  pons  Varolii;  13,  me- 
dulla oblongata;  14,  anterior  pyramids;  15,  olivary  body ;  16,  restiform  body  (only 
partially  visible);  1*7,  17,  hemispheres  of  the  cerebellum;  18,  fissure  separating 
these  hemispheres;  19,  19,  first  and  second  convolutions  of  the  inferior  aspect  of 
the  frontal  lobe  with  the  intervening  sulcus ;  20,  external  convolutions  of  the  frontal 
lobe;  21,  optic  tract;  22,  olfactory  nerve ;  22',  section  of  olfactory  nerve,  showing 
its  triangular  prismatic  shape :  the  trunk  has  been  raised  to  show  the  sulcus  in 
which  it  is  lodged ;  23,  ganglion  of  the  olfactory  nerve ;  24,  optic  chiasm  ;  25,  motor 
oculi ;  26,  pathetieus  ;  27,  trigeminus ;  28,  abducens ;  29,  facial ;  30,  auditory  nerve 
and  nerve  of  Wrisberg;  31,  glosso-pharyngeal ;  32,  pneumogastric ;  33,  spinal  ac- 
cessory ;  34,  hypo-glossal. 


108  "  THE  BE  Am. 

The  comparative  weights  of  the  component  parts  of  the 
encephalon  are,  in  ai)proximate  figures,  about  one  fiftieth  of 
the  entire  weight  for  the  pons  Varolii  and  the  medulla  oblon- 
gata, taken  together ;  one  tenth  of  the  entire  weight  for  the 
cerebellum  ;  and  the  balance  of  the  total  weight  for  the  cere- 
brum and  the  basal  ganglia  inclosed  within  its  substance. 
These  proportions  show  a  slight  variation  in  the  two  sexes, 
but  not  to  so  marked  an  extent  as  to  render  this  statement 
far  from  a  correct  one. 

It  may  be  stated,  as  a  rule,  that  the  relative  proportion  of 
the  cerebrum  to  that  of  the  cerebellum  is  greater  in  the  intel- 
lectual races.  The  cerebrum  is  developed  in  individuals  in 
proportion  to  their  intellectual  power,  although  its  absolute 
size  may  not  be  taken  as  a  guide  to  the  quality  of  the  mind, 
since  it  is  undoubtedly  true  that  the  brain,  as  well  as  the 
muscular  tissue,  can  be  improved,  in  quality^  by  exercise. 
That  there  are  important  individual  differences  in  the  quality 
of  the  generating  nervous  matter  is  evidenced  by  the  fact  that 
some  small  brains  actually  accomplish  more  and  better  work 
than  larger  ones  ;  and  that  many  women  often  show  a  higher 
degree  of  mental  acumen  than  men,  in  spite  of  the  fact  that 
they  have  brains  which  are  lighter  in  avoirdupois. 

From  a  most  carefully  prepared  table  of  the  weight  of 
brain  substance  possessed  by  men  of  renown  as  intellectual 
giants,  as  well  as  those  which  revealed  an  unusual  develop- 
ment of  brain  after  death,  contained  in  the  work  of  a  promi- 
nent author,'  some  interesting  facts  are  revealed. 

The  heaviest  brains '  on  record  (where  the  statements  are 
to  be  relied  upon)  were  possessed  by  an  Indian  squaw,  a  con- 
genital imbecile,  and  an  ignorant  bricklayer,  both  of  whom 
outweighed  Cuvier  and  Abercrombie  ;  while  a  boy  of  thirteen 
years  of  age  had  five  ounces  more  brain  than  Webster  and 
Agassiz.     Such  a  table  shows  the  utter  absurdity  of  attempt- 

»  A.  Flint,  Jr ,  "Tcxt-Book  of  Physiology."     D.  Applcton  &  Co.,  New  York. 

'  Conp^cnital  imbecile,  aged  thirty,  7(H  ounces  of  brain  substance ;  bricklayer,  67 
ounces;  Cuvier,  OH  ounces;  Abercrombie,  63  ounces;  Webster,  63^  ounces;  Agassiz, 
53]^  ounces. 


WEIGHT  OF  TEE  BRAIN. 


109 


ing  to  apply  to  individuals  the  rule  that  the  greatest  brain 
power  is  possessed  by  the  one  having  the  greatest  amount  of 
brain  substance. 


Fig.  29. —  Convolutions  on  the  internal  aspect  of  the  hemispheres.  (After  Sappey.) 
frontal  lobe ;  2,  sphenoidal  lobe ;  3,  3,  convolution  of  the  corpus  callosum ;  4,  4,  convo- 
lutions forming  the  middle  group  of  the  internal  surface ;  5,  5,  convolutions  of  the 
anterior  group ;  6,  convolutions  of  the  posterior  group ;  Y,  sulcus  separating  the  mid- 
dle from  the  posterior  group ;  8,  sulcus  separating  the  anterior  and  the  middle  group ; 
9,  section  of  the  corpus  callosum;  10,  genu  of  the  corpus  callosum;  11,  rostrum  of 
the  corpus  callosum;  12,  posterior  extremity  of  the  corpus  callosum;  13,  fornix; 
14,  section  of  the  fornix;  15,  left  anterior  crus  of  the  fornix,  passing  into  the  inter- 
nal wall  of  the  optic  thalamus,  to  reach  the  corresponding  corpus  albicans — course 
indicated  by  a  dotted  line;  16,  foramen  of  Monro;  17,  corpus  albicans,  in  which  the 
anterior  crus  of  the  fornix  bends  upon  itself,  in  the  form  of  a  figure  of  eight,  to  be 
lost  in  the  substance  of  the  optic  thalamus;  18,  septum  lucidum;  19,  section  of  the 
choroid  plexus;  20,  pineal  gland;  21,  left  superior  peduncle  of  the  same;  22,  sec- 
tion of  the  gray  commissure  of  the  third  ventricle ;  23,  tubercula  quadrigemina,  above 
which  are  seen  the  pineal  gland  with  its  inferior  peduncle  and  the  posterior  com- 
missure ;  24,  section  of  the  anterior  commissure ;  25,  aqueduct  of  Sylvius ;  26,  section 
of  the  valve  of  Vieussens ;  27,  fourth  ventricle ;  28,  28,  section  of  the  middle  lobe 
of  the  cerebellum  ;  29,  arbor  vitae ;  30,  corpus  cinereum ;  31,  pituitary  body  ;  32,  optic 
nerve;  33,  pons  Varolii;  34,  medulla  oblongata. 


EFFECTS  OF  miRA-CEREBRAL  LESIONS. 
The  physiology  of  the  great  ganglia  of  the  cerebrum  is 
far  from  being  satisfactorily  determined,  since  the  experi- 
ments of  different  observers  apparently  prove  most  glaring 
contradictions.  It  is,  however,  probable  that  the  two  subdi- 
visions of  the  corpus  striatum  (the  caudate  and  the  lenticular 

10 


110  THE  BRAIN. 

nuclei)  have  motor  functions  of  a  character  which  are  not  yet 
positively  decided,  while  the  attributes  of  the  optic  thalamus 
are  still  involved  in  more  or  less  obscurity.' 

It  can  safely  be  considered  as  proven  that  the  anterior 
pair  of  the  corpora  quadrigemina  (the  nates)  are  in  some  way 
concerned  in  the  special  sense  of  vision,  and  belong  to  the 
optic  apparatus,  although  the  motions  of  the  eyeball  seem  to 
be  more  directly  influenced  than  vision  itself.  The  posterior 
pair  are  probably  functionally  associated  with  the  coordina- 
tion of  muscular  movements.  The  fibers  of  the  lemnis- 
cus or  fillet-tract  can  apparently  be  traced  in  part  to  these 
bodies. 

The  internal  capsule  of  the  cerebrum  seems  to  be  one 
of  the  most  important  regions  of  the  brain,  from  a  clinical 
standpoint,  since  the  slightest  pressure  upon  the  fibers  of 
which  it  is  composed  produces  symptoms  which  vary  with 
the  portion  pressed  upon.  A  secondary  degeneration,*  which 
descends  along  the  nerve  fibers  of  the  cms,  pons,  medulla, 
and  spinal  cord,  is  inevitably  the  result  of  disease  of  this 
portion  of  the  cerebrum. 

If  the  region  occupied  by  the  pyramidal  tracts  be  the 
seat  of  pressure  or  disease,  paralysis  of  motion,  chiefly  con- 
fined to  the  opposite  side,  results ;  if  the  sensory  tracts  be 
affected,  a  condition  of  ancBstJiesia  of  the  opposite  side  is 
produced.  Choreic  movements,  which  vary  in  degree  and 
type,  and  which  may  appear  as  athetosis,  ataxia,  true  chorea, 
or  tremor,  are  strongly  diagnostic  of  lesion  of  the  internal 
capsule,  provided  they  follow  an  attack  of  hemiplegia  or 
he  mi-anaesthesia. 

Lesions  of  the  parts  adjoining  the  internal  capsule  (the 
caudate  nucleus,  the  lenticular  nucleus,  and  the  optic  thala- 
mus), if  the  seat  of  haemorrhage,  tumors,  or  other  conditions 
which  are  capable  of  causing  pressure  upon  it,  may  produce 

*  To  what  extent  this  *];anglion  presides  over  or  influences  sensory  perceptions  must 
be  considered  unsettled.  For  opinions  on  the  subject,  the  reader  is  referred  to  a  subse- 
quent page  of  this  volume. 

'  For  the  effects  of  this  descending  type  of  secondary  degeneration  of  nerve  tissue, 
see  a  subsequent  page  of  this  yolumc. 


SURGICAL    GUIDES  TO   CEREBRUM.  \\\ 

symptoms  similar  to  those  of  disease  of  the  internal  capsule 
itself. 

When  the  central  portions  of  the  cerebral  hemispheres 
are  the  seat  of  some  type  of  disease  which  has  been  suddenly 
developed,  as  in  hsemorrhage,  acute  softening,  etc.,  symptoms 
referable  to  the  optic  apparatus  are  usually  present,  in  addi- 
tion to  the  other  symptoms  which  have  been  given  above. 
Thus,  the  eyes  may  be  turned  away  from  the  paralyzed  side, 
and,  therefore,  toward  the  seat  of  the  lesion  ;  the  head  also  is 
often  similarly  turned ;  and,  in  case  the  injury  done  to  the 
brain  is  severe  or  extensive,  a  very  marked  rise  in  the  surface 
temperature  of  the  body  may  be  observed. 

When  the  pressure  upon  the  central  portions  of  the 
cerebral  hemispheres  is  gradual^  as  in  the  case  of  growing 
tumors,  we  have  developed  certain  special  signs,  which  de- 
pend upon  the  situation  of  the  tumor  and  the  line  of  its 
greatest  pressure ;  but  we  are  also  liable  to  have  changes 
develop  in  the  eye — those  of  ' '  neuro-retinitis  " — which  may 
result  in  the  condition  known  by  ophthalmologists  as  the 
''choked  disk." 

THE   SURGICAL  BEARINGS  OF   CEREBRAL  TOPOGRAPHY. 

In  the  year  1861,  Broca  invented  a  scientific  method  of  de- 
termining the  relations  of  different  parts  of  the  cerebrum  to 
the  exterior  of  the  skull,  which  consisted  of  driving  pegs 
through  the  skulls  of  animals  and  of  cadavers,  holes  having 
been  previously  bored  through  the  bone  in  order  to  prevent 
fracture  and  injury  to  surrounding  parts.  The  skull-cap  was 
then  removed  with  extreme  care,  and  the  convolutions  which 
were  wounded  were  thus  determined.  It  was  discovered  by 
this  observer  that  the  fissure  of  Rolando^  whose  relation  to 
the  coronal  suture  was  then  unknown,  lay  obliquely,  and  that 
its  upper  extremity  could  be  placed,  with  great  accuracy  in 
man,  at  a  point  situated  40  mm.  behind  the  coronal  suture. 
It  can  also  be  located  at  one  half  inch  behind  the  central 
point  of  a  line  extending  from  the  root  of  the  nose  to  the 
occipital  protuberance. 


112  THE  BRAIN. 

This  fissure  was  particularly  studied  on  account  of  its  re- 
lation to  the  motor  region  of  the  cortex,  and  its  exact  bearing 
to  the  exterior  of  the  skull  was  therefore  of  great  importance. 

The  same  observer  was  also  able  to  prove  that  the  external 
parieto-occipital  fissure  of  the  cerebrum  lay  under  the  lamh- 
doid  suture  of  the  cranium.  In  1873,  the  experiments  of 
Heftier  and  Bischoff  were  added  to  those  of  Broca,  while  Tur- 
ner followed  with  his  researches  in  1874  and  Fere  in  1875. 
The  drawings  which  Turner  furnished  were  admirable  in  their 
way,  but  are,  to  my  mind,  hardly  adapted  to  the  purposes  of 
the  surgeon,  since  the  guides  which  the  bony  prominences  of 
the  skull  afford  are  not  brought  into  such  prominence  as  to 
be  readily  comprehended  by  the  casual  reader.  If  the  sur- 
geon is  to  utilize  the  valuable  researches  of  the  investigators 
above  named  (and  several  most  brilliant  surgical  operations 
have  already  been  performed  from  the  light  which  the  newly 
acquired  knowledge  of  the  topography  of  the  cerebrum  has 
afforded),  certain  bony  prominences  of  the  skull  must  be  des- 
ignated, as  of  importance,  as  guides  to  the  special  convolu- 
tions and  fissures  of  the  brain.  Now,  there  is  one  line  which 
is  easily  drawn  upon  the  head  of  the  living  subject  (the  alve- 
olo-condyloid  plane  of  Broca),  upon  which  perpendicular  lines 
may  be  described,  intersecting  certain  bony  points,  which 
lines  can  be  utilized  as  guides  to  parts  whose  situation  is  now 
positively  known.  This  base  line  should  be  a  straight  one, 
and  should  intersect  the  tip  of  the  mastoid  process  and  the 
line  of  the  cusps  of  the  teeth  of  the  upper  jaw.* 

This  is  the  natural  base  line  of  the  human  skull,  when  the 
lower  jaw  is  removed  and  the  skull  placed  upon  a  table  ; 
hence  it  is  a  plane  admirably  adapted  for  the  study  of  the 
guides  (which  will  be  given),  upon  the  skeleton,  in  the  office 
of  each  practitioner,  previous  to  an  operation.  Furthermore, 
a  skull  can  easily  be  painted  upon  its  exterior  so  as  to  bring 
the  lines,  designated  as  important,  into  prominence,  and  so 

'  This  author  places  the  line  as  intersecting  the  eondyh  of  the  occipitcU  bone  ;  but,  as 
t^ia  can  not  be  felt  in  the  living  subject,  and  as  it  corresponds  to  the  tip  of  tlic  mastoid 
process,  I  have  modified  the  guide  so  as  to  simplify  its  exact  situation  upon  the  exte|ior 
of  the  skull. 


SURGICAL   GUIDES  TO   CEREBRUM.  II3 

assist  the  surgeon  in  the  review  of  those  points  which  pos- 
sess special  value.  The  contributions  of  Fere  and  Horsley 
are,  to  my  mind,  the  best  of  all  the  authors  named,  since  the 
points  most  needed  by  the  surgeon  in  a  practical  way  are 
given.  A  resume  of  Fere's  guides  is  so  tersely  and  clearly 
stated  by  Seguin  that  it  would  be  useless  to  attempt  to  im- 
prove upon  it.  It  will  be  perceived  in  the  plate,  introduced 
to  make  these  guides  more  clear  than  a  mere  verbal  descrip- 
tion, that  the  line  described,  viz.,  the  alveolo-condyloid  plane 
of  Broca,  is  used  as  a  base  line  upon  which  to  erect  perpen- 
diculars at  distances  which  can  be  accurately  measured  upon 
it ;  and  that  these  perpendicular  lines  intersect  certain  regions 
which,  from  facts  previously  recorded,  are  of  the  greatest 
importance.  I  quote  the  resume  of  Seguin '  upon  this  special 
department  of  cerebral  localization  : 

''1.  A  vertical  line  (a)  drawn  from  the  alveolo-condyloid 
plane,  through  the  external  auditory  meatus  upward,  will 
pass  through  or  very  near  to  the  bregma,  or  line  of  junction 
of  the  frontal  and  parietal  bones  at  the  vertex  ;  it  passes 
through  the  anterior  (lower)  extremity  of  the  fissure  of 
Rolando. 

"2.  If,  from  the  upper  end  of  this  vertical  line  a,  we  meas- 
ure a  distance  of  45  mm."  backward  toward  the  occiput  and 
draw  a  descending  vertical  line  (1-2),  we  mark  out  the  loca- 
tion of  two  most  important  parts  of  the  cerebrum,  viz.,  the 
posterior  extremity  of  the  fissure  of  Rolando  [at  5],  and  the 
posterior  limit  of  the  thalamus  opticus  in  the  hemisphere 
[at  c]. 

"3.  To  conclude  with  the  occipital  end  of  the  skull ;  if  we 
can  make  out  with  the  fingers  the  lambdoid  suture  at  the 
median  line,  we  thus  learn  the  situation  of  the  subjacent 
occipito-parietal  fissure,  which  separates  the  parietal  and 
occipital  lobes. 

"4.  The  last  vertical  line  worth  noting  is  one  drawn  at  a 
distance  of  30  mm.  forward  of  the  auriculo-bregmatic  line. 
This  vertical  line  (3-4)  will  pass  through  the  middle  fold  of 

*  "  Medical  Record,"  1878.         ^  x  millimetre  is  about  one  twenty-fifth  of  an  inch. 


114 


THE  BRAIK 


the  third  frontal  convolution  (just  forward  of  the  speech  cen- 
ter), and  will  also  indicate  the  anterior  limit  of  the  central 
cerebral  ganglia,  viz.,  the  head  of  the  nucleus  caudatus  in 
the  hemisphere  [at  d\ 


Fio.  30. — Outline  of  skull  resting  upon  the  alveolo-condyloid  plane  of  Broca.     (Modified 
from  Topinard's  "Anthropology"  by  Seguin.) 

Vertical  line  a,  or  aurieulo-brcgmatic.  Line  9-10,  drawn  parallel  to  the  plane  of  Broca. 
Upon  this  line,  at  a  distance  of  45  mm.  posterior  to  the  bregma,  a  vertical  line,  1-2, 
will  pass  through  the  upper  (inner)  end  of  the  fissure  of  Rolando,  A,  6,  and  through 
the  posterior  extremity  of  the  thalamus  opticus  (c).  A  third  vertical  line,  3-4,  drawn 
at  30  mm.  forward  of  the  bregma,  will  pass  through  the  fold  of  the  third  frontal 
gyrus  (a),  and  through  the  head  of  the  nucleus  caudatus  {d).  The  horizontal  line, 
7-8,  at  46  ram.  below  the  bregma  (scalp),  indicates  the  upper  limit  of  the  central 
ganglia.  The  third  horizontal  line,  5-6,  passing  through  the  external  angular  pro- 
cess of  the  frontal  bone  and  the  occipito-parietal  junction,  approximately  indicatea 
the  course  of  the  fissure  of  Sylvius,  and  serves  for  measurements.  At  18  or  20  mm. 
behind  the  external  angular  process  on  this  line  is  the  speech  center  of  Broca ;  5  to 
8  mm.  behind  the  intersection  of  3-4  and  5-6  is  the  beginning  of  the  fissure  of  Syl- 
vius, and  at  28  or  30  mm,  behind  this  intersection  is  the  lower  end  of  the  fissure  of 
Rolando,  6,  6,  placed  a  little  too  far  back  in  the  cut.  At  x  (near  6),  near  the  median 
line,  is  the  location  of  the  occipito-parietal  fissure.  S,  the  stephanion  ;  P,  the  pterion. 
These  two  parts  will  be  discussed  in  a  subsequent  page. 


"6.  The  upper  level  of  the  central  cerebral  ganglia  may- 
be quite  exactly  indicated  by  a  horizontal  line  drawn  at  a  dis- 
tance of  45  mm.  below  the  surface  of  the  scalp,  at  the  bregma, 
(or  35  below  the  surface  of  the  bare  skull  at  the  same  point). 
This  line  (7-8)  also  runs  across  the  middle  regions  of  the  mo- 
tor district  of  the  convolutions,  containing  centers  for  the  face 
and  upper  extremities. 


SURGICAL    GUIDES  TO   CEREBRUM.  115 

''Q.  The  external  angular  process  of  the  frontal  bone,  not 
difficult  to  define  in  the  living  subject,  is  the  starting-point  of 
another  horizontal  line  {5-Q\  whose  posterior  extremity  passes 
a  little  below  the  lambdoid  suture.  Upon  this  horizontal  line 
we  can,  by  measurement,  determine  the  location  of  certain 
parts.  Thus,  at  a  distance  of  18  or  20  mm.  behind  the  exter- 
nal angular  process,  lies  the  folded  part  of  the  third  frontal 
convolution  {a).  This  point,  in  many  heads,  will  correspond 
to  the  vertical  line  3-4. 

''  7.  The  situation  of  the  fissure  of  Sylvius  may  be  approx- 
imately ascertained  in  the  following  manner :  Its  middle  por- 
tion extends  horizontally,  almost  under  the  upper  part  of  the 
squamous  suture,  which  in  the  living  subject  is  to  be  found  a 
little  below  the  horizontal  line  5-6.  The  anterior  extremity 
or  beginning  of  the  fissure  of  Sylvius  is  a  little  below  this 
horizontal  line,  at  a  distance  of  some  5  to  8  mm.  posterior  to 
the  intersection  of  3-4  and  ^-Q>^  and  consequently  about  22  or 
25  mm.  anterior  to  the  auriculo-bregmatic  line  a.  Lastly, 
according  to  Turner,  the  parietal  eminence  almost  always 
overlies  the  supra-marginal  gyrus  (P",  Fig.  20),  consequently 
the  posterior  extremity  of  the  fissure  of  Sylvius  is  likewise  in 
this  vicinity. 

"8.  The  angular  gyrus  is  to  be  found  below  and  behind 
the  parietal  eminence,  a  little  above  the  horizontal  line  drawn 
from  the  external  angular  process  {Q-Q). 

"  9.  The  anterior  (lower)  end  of  the  fissure  of  Rolando  lies 
at  a  distance  of  28  or  30  mm.  behind  the  line  3-4,  and  a  little 
above  6-Q.  It  is,  therefore,  a  few  millimetres  anterior  to  the 
vertical  line  a." 

With  this  plate  as  a  guide,  and  with  a  thorough  knowledge 
of  the  facts  comprised  in  previous  pages  of  this  chapter,  it  is 
not  out  of  the  bounds  of  possibility  to  definitely  locate  the 
existence  of  lesions  in  certain  portions  of  the  human  brain, 
to  map  out  their  situation  upon  the  exterior  of  the  skull, 
and  to  reach  them  with  surgical  means  of  relief,  provided  the 
case  be  one  which  would  justify  such  a  measure.  Broca  has 
been  successful  in  trephining  directly  over  an  abscess  of  the 


third  frontal  convolution,  which  was  suspected.  Successful  i 
cases  have  been  reported  of  trephining  of  the  skull  for  frag- 
ments of  the  inner  plate  which  were  compressing  the  as-  \ 
cending  gyri  of  the  frontal  and  parietal  lobes,  thus  causing  ' 
paralysis.  Tumors  of  the  brain  have  lately  been  located  ac-  i 
curately  and  removed  by  the  knife  and  trephine.  ^j 

Horsley  has  lately  added  a  valuable  contribution  to  the  : 
subject  of  cortical  localization,  based  upon  experimentation  | 
on  monkeys,  and  also  on  observations  in  ten  cases  where  the  i 
diseased  area  was  successfully  determined  in  the  human  j 
subject  prior  to  operative  procedure.  His  conclusions  are  ! 
therefore  worthy  of  note.     They  may  be  summarized  as :  \ 

1.  SulcU  or  fissures^  are  not  to  he  regarded  as  accurate  -''''  j 
boundaries  to  cortical  areas,  although  they  constitute  valu-  i 
able  landmarks  for  operative  procedures  upon  the  cortex.         ^^S 

2.  The  motor  centers,  according  to  this  observer,  are  capa-  \ 
ble  of  further  subdivision  than  those  described  by  Ferrier,  i 
and  they  overlap  each  other  at  their  borders.  '    j 

3.  The  face  area,  taken  as  a  whole,  embraces  the  lower  i 
third  of  both  central  convolutions  (4  and  5  in  Fig.  22).  This  ! 
is  subdivided  into  (a)  an  upper  and  anterior  portion,  which  ; 
controls  the  upper  part  of  the  face  and  the  angle  of  the  mouth;  ] 
(b)  the  anterior  half  of  the  lower  portion,  which  governs  the  \ 
movements  of  the  vocal  cords ;  and  {c)  the  posterior  half  of  \ 
the  lower  portion,  which  governs  the  lower  part  of  the  face  ; 
and  the  floor  of  the  mouth.  -^t 

4.  The  area  for  the  upper  limb  occupies  the  middle  third  j 
of  both  central  convolutions,  and  also  the  base  of  the  superior  ; 
and  middle  frontal  convolutions.  It  joins,  and  also  merges  : 
with,  the  area  for  movements  of  the  head  and  neck  in  the  I 
middle  frontal  gyrus,  and  with  that  of  the  leg  in  the  superior  i 
frontal  gyrus.  ; 

In  the  area  described  as  pertaining  to  the  upper  limb,  the  -  \ 
uppermost  part  is  thought  by  Horsley  to  control  the  muscles  j 
of  the  shoulder ;  below,  and  posteriorly,  the  elbow  is  repre-  ^1 
sen  ted ;  still  further  below  and  somewhat  anteriorly,  the  S| 
wrist ;  next  in  order,  anteriorly,  the  finger-movements  are  &| 


SURGICAL   GUIDES  TO   CEREBRUM.  II7 

placed ;  and  lowest  of  all,  and  posteriorly,  the  thumb-move- 
ments are  located.  These  views  he  substantiates  by  observa- 
tions made  in  cases  of  cortical  tumors,  where  spasm  w^as 
developed  and  appeared  first  in  an  isolated  region  of  the 
upper  limb. 

5.  The  area  for  the  lower  limb  is  described  by  this  ob- 
server as  embracing  the  upper  portions  of  the  two  central 
convolutions ;  also  the  whole  of  the  superior  parietal,  the 
base  of  the  superior  frontal  convolutions,  and  the  para-central 
lobule.  This  description  is  not  materially  different  from  that 
of  Ferrier  (Fig.  26). 

The  subdivisions  of  this  area  are  as  yet  incompleted,  but 
the  points  given  are  of  interest  to  the  surgeon.  The  move- 
ments of  the  big  toe  are  referred  to  the  para-central  lobule  ; 
those  of  the  leg  alone  to  the  middle  part ;  those  of  the  leg 
and  arm  combined  to  the  most  anterior  portion.  Most  of 
these  conclusions  agree  in  the  main  with  those  of  Ferrier. 

6.  The  area  for  movements  of  the  head  and  necJc,  and  also 
for  conjugate  deviation  of  the  eyes,  is  placed  by  this  observer 
(in  common  with  Ferrier  and  Munk)  in  the  bases  of  the  three 
frontal  gyri  (see  12  in  Fig.  25). 

7.  Respecting  the  steps  required  to  locate  the  fissures  of 
E-olando  and  Sylvius  upon  the  human  subject  during  life  (as 
a  basis  for  surgical  procedures),  the  following  conclusions  are 
reached : 

{a)  The  method  first  described  by  Prof.  Thane  for  locating 
Rolando' s  fissure  is  adopted.  A  careful  measurement  is  first 
made  along  the  mesial  line  of  the  skull,  starting  from  the  root 
of  the  nose  and  extending  to  the  occipital  protuberance. 
This  distance  is  then  halved.  The  fissure  of  Rolando  at  its 
upper  part  lies  one  half  inch  posteriorly  to  its  central  point. 
A  strip  of  flexible  iron  (with  a  movable  arm  placed  at  an 
angle  of  sixty- seven  degrees  to  it)  is  now  laid  upon  the  middle 
line  of  the  head,  the  point  of  junction  of  the  movable  arm 
with  the  mesial  strip  being  carefully  located  at  the  point 
previously  determined  as  overlying  the  upper  end  of  Ro- 
lando's fissure.     When  this  is  accurately  done,  the  movable 


118 


THE  BRAIK 


arm  marks  the  course  of  the  upper  two  thirds  of  the  fissure 
of  Rolando,  but,  as  the  lower  third  tends  to  bend  slightly 
backward,  it  does  not  as  clearly  define  the  lower  third  of  that 
fissure. 

{h)  To  accurately  locate  the  fissure  of  Sylvius  upon  the 
skull  no  little  precision  is  required.  A  few  points  in  the 
bones  of  the  skull  have  first  to  be  accurately  determined. 
These  are  as  follows :  (1)  The  point  where  the  terajjoral  ridge 
crosses  the  coronal  suture  (the  '-'- stejp7ianion^\  This  can 
usually  be  felt  with  the  finger,  the  coronal  suture  appearing 
to  the  touch  either  as  a  depression  or  as  a  ridge  lying  between 
two  grooves.  (2)  Exactly  midway  between  the  stephanion 
and  the  upper  border  of  the  zygoma,  on  a  line  drawn  vertical 
to  the  zygoma  toward  the  stephanion,  lies  another  point 
known  as  the  ^^jpteriony  (3)  To  determine  the  highest  point 
of  the  suture  which  exists  between  the  squamous  portion  of 
the  temporal  bone  and  the  inferior  border  of  the  parietal 
bone  (the  "•  squamo-parietal''^  suture\  a  measurement  has  to 
be  made,  because  that  suture  can  not  be  felt  beneath  the 
temporal  muscle. 

In  front  of  the  temporo-m axillary  articulation,  an  upright 
upon  the  line  4-2  in  Fig.  30  would  cross  the  zygoma.  The 
junction  of  the  upper  and  middle  thirds  of  the  measurement, 
made  upon  such  a  vertical  line  between  the  upper  border  of  the 
zygoma  and  the  ridge  formed  by  the  temporal  muscle,  indi- 
cates the  situation  of  the  highest  point  of  the  squamo-parietal 
suture. 

The  anterior  limb  of  the  Sylvian  fissure  starts  from  a  point 
which  lies  from  one  half  to  one  line  (one  twenty -fourth  to 
one  twelfth  of  an  inch)  in  front  of  the  '^pterion."  It  runs 
anteriorly  and  upward  from  that  point.  The  posterior  limb 
passes  backward  and  slightly  upward  from  the  same  point. 

8.  The  sulci  of  the  frontal  lobe,  and  also  the  inter -parietal 
sulcus  (which  limits  the  so-called  ''motor  area"  of  the  cortex 
posteriorly),  are  next  to  be  located  upon  the  exterior  of  the 
skull,  in  order  to  map  out  the  convolutions.  The  guides  to 
the  sulci  are  as  follows : 


4 


EORSLEY'S   VIEWS.  II9 

The  precentral  sulcus  lies  somewliat  behind  the  coronal 
suture  and  parallel  to  it.  It  extends  to  about  the  middle  of 
Eolando's  fissure. 

The  inferior  frontal  sulcus  diverges  from  the  precentral 
at  about  the  level  of  the  temporal  ridge. 

The  superior  frontal  sulcus  starts  at  a  point  in  the  pre- 
central gyrus  somewhat  posterior  to  the  line  of  the  precentral 
sulcus  if  continued  upward.  The  exact  point  is  about  mid- 
way between  the  fissure  of  Rolando  and  an  upward  continua- 
tion of  a  line  in  the  direction  of  the  precentral  sulcus.  Its 
altitude  in  the  cerebrum  is  slightly  above  the  level  of  a  point 
(midway  between  the  mesial  line  of  the  skull  and  the  center 
of  the  parietal  eminence)  which  designates  the  lower  limit  of 
the  superior  parietal  convolution. 

The  inter-parietal  sulcus  in  its  ascending  course  starts 
from  a  point  on  a  level  with  the  junction  of  the  middle  and 
lower  thirds  of  Holando's  fissure.  It  turns  backward  on  a 
level  situated  midway  between  the  mesial  line  of  the  skull 
(marked  by  the  longitudinal  fissure)  and  the  center  of  the 
parietal  eminence. 

There  are  certain  suggestions,  which  may  be  thrown  out  in 
this  connection,  which  are  safe  ones  to  follow  in  cases  where 
the  propriety  of  surgical  relief  is  called  in  question.  These 
may  be  stated  in  the  form  of  propositions,  which  are  of  neces- 
sity based  upon  the  contents  of  the  previous  lectures. 

1.  If  the  injury  sustained  (provided  the  case  in  question 
be  one  of  a  traumatic  origin)  be  situated  over  the  motor  area 
of  the  cortex,  the  presence  of  ancesthesia  in  combination  with 
motor  hemiplegia  is  a  contra-indication  to  attempts  at  sur- 
gical relief.  This  symptom  (anaesthesia)  probably  indicates 
some  injury  to  the  sensory  fibers  which  enter  the  posterior 
third  of  the  internal  capsule ;  hence  the  lesion  is  probably 
too  extensive  to  be  relieved  by  trephining. 

2.  If  the  sensory  region  of  the  cortex  be  involved,  and 
paralysis  or  convulsive  movements  occur,  an  operation  is 
contra-indicated ;  since  the  lesion  has  probably  been  so  ex- 
tensive as  to  extend  to  the  motor  area,  or  has  involved  or 


120 


THE  BRAIK 


compressed  the  cerebrum  at  a  point  removed  from  the  appar- 
ent seat  of  injury. 

3.  The  occurrence  of  paralysis  on  the  same  side  as  that 
upon  which  the  injury  was  received  is  always  a  contra-indica- 
tion  to  any  surgical  procedure  at  the  seat  of  injury  ;  since  it 
probably  indicates  some  lesion  of  the  opposite  side,  doubtless 
dependent  upon  transmitted  force  {contre-coup). 

4.  The  completeness  of  the  paralysis  may  be  often  taken 
as  a  guide  to  the  amount  of  injury  done  to  the  cerebrum  :  if 
the  paralysis  be  very  profound,  the  chance  of  success  from 
trephining  is  extremely  small,  since  the  injury  has  probably 
affected  parts  deeper  than  the  cortex. 

5.  The  appearance  of  paralysis  of  any  of  the  special 
nerves  of  the  cranium^  or  the  development  of  the  symptoms 
due  to  lesions  of  the  base  of  the  brain  or  of  the  basal  ganglia, 
such  as  the  Cheyne-Stokes  respiration,'  choked  disk,  and 
vomiting,  may  be  regarded  as  contra-indications  to  surgical 
interference. 

6.  When  an  injury  to  the  skull  is  followed,  after  a  lapse 
of  some  weeks,  by  the  ataxic  form  of  aphasia^  the  diagnosis 
of  abscess  of  the  base  of  the  third  frontal  convolution,  or  pos- 
sibly involving  the  island  of  Reil  or  the  white  substance  situ- 
ated between  the  third  frontal  convolution  and  the  basis  of 
the  cerebrum,  may  be  safely  made.'  In  such  a  case  the  opera- 
tion of  trephining,  as  performed  by  Broca,  affords  a  strong 
probability  of  relief. 

7.  Cases  of  injury  which  are  folloiced  immediately  by 
ataxic  or  motor  aphasia  are  strongly  diagnostic  of  either  a 
spicula  of  bone  or  the  pressure  of  a  clot  in  the  neighborhood 
of  the  center  of  Broca.  The  former  condition  would  be  strong- 
ly in  support  of  surgical  interference,  since  it  would  probably 
continue  to  create  pressure  or  irritation  until  removed,  while 
the  pressure  of  a  clot  might  also  be  relieved  by  trephining. 

*  A  respiration  whose  rhythm  steadily  increases,  and  then  decreases,  in  a  short  int^ 
val  of  time;  described  in  1818  by  Cheyne,  and  by  Stokes  in  1846.  -  . 

'  Authorities  are  not  all  in  accoid  with  this  statement.  The  author  has  discussed  tht 
conditions  known  as  "  word-blindness  "  and  '*  word-deaf ncss  "  in  previous  pages. 


INDICATIONS  FOB   TEEPHININQ.  121 

8.  If  the  region  over  the  fissure  of  Rolando  be  subjected 
to  apparent  injury,  and  the  symptoms  of  some  of  the  special 
types  of  monoplegia  appear  (affecting  the  muscles  of  the  face, 
arm,  leg,  or  any  of  these  combined),  or  even  the  occurrence  of 
a  slight  form  of  hemiplegia  follow,  successful  results  from 
trephining  may  be  reasonably  expected.  The  presence  of 
anaesthesia,  as  before  mentioned,  would,  however,  still  be  a 
strong  contraindication  to  such  a  step,  since  it  would  prove 
that  the  lesion  was  probably  of  too  deep  a  character  to  be 
benefited  by  the  simple  removal  of  a  button  of  bone,  as  the 
posterior  third  of  the  internal  capsule  would  probably  be 
found  to  be  impaired.  It  must  be  also  remembered  that  the 
motor  paralysis,  of  whatever  kind  it  may  be,  must  be  confined 
to  the  side  of  the  body  opposite  to  the  seat  of  injury,  if  benefit 
is  to  be  expected.  The  type  of  monoplegia  which  exists  may 
often  be  used  as  a  guide  to  determine  the  extent  of  the  lesion 
as  well  as  its  situation. 

9.  Convulsive  attacks,  which  invariably  begin  by  spas- 
modic movements  of  some  special  locality  of  the  hody^  and 
whose  cause  is  apparently  a  cerebral  lesion  or  a  traumatism 
of  the  head,  may  be  treated  successfully  in  some  cases  by  a 
trephine  over  the  motor  center  of  the  part  which  is  primarily 
attacked  with  spasm. 

10.  Homonymous  hemianopsia  (when  uncomplicated)  points 
strongly  to  a  lesion  of  the  cuneus.  Trephining  has  been  suc- 
cessfully performed  over  this  region  of  the  occiput  for  sus- 
pected tumor,  whose  presence  was  revealed  by  this  symptom 
alone  (Seguin,  Weir). 

DIAGNOSTIC  SYMPTOMS  OF  NON-CORTICAL  LESIONS   OF  THE 

CEREBRUM. 

Many  of  the  clinical  facts  pertaining  to  non-cortical  cere- 
bral lesions  may  be  thus  summarized  : 

Profound  coma  is  more  often  encountered  in  non-cortical 
lesions  than  in  cortical,  possibly  because  the  cerebro-spinal 
fluid  is  more  liable  to  be  displaced  from  the  ventricles 
(Buret). 


122 


TEE  BRAIN. 


Hemiplegia  commonly  exists  in  comMnation  with  more  or 
less  hemiancestJiesia^  and  paresis  of  the  lower  part  of  the 
face.  These  symptoms  are  observed,  as  a  rule,  upon  the  side 
of  the  body  opposed  to  the  cerebral  lesion. 

Pain^  when  present  in  the  head,  is  less  circumscribed  than 
in  cortical  disease,  and  is  not  increased  by  percussing,  or  eli- 
cited by  that  step  when  absent. 

Muscular  rigidity  in  the  paralyzed  muscles  develops  late. 
Typical  monoplegia  is  probably  never  observed. 

Tremor^  hemichorea^  and  athetosis  are  not  uncommon 
sequelae  of  non-cortical  cerebral  lesions. 

The  senses  of  sights  smell,  hearing,  and  tactile  sensibility 
are  occasionally  impaired  to  a  greater  or  less  extent  by  non- 
cortical  lesions.  The  seat  of  the  lesion  will  modify  the  evi- 
dences of  such  impairment,  becsruse  the  fibers  of  some  of  the 
cranial  nerves  may  be  involved  by  the  lesion,  while  others 
may  escape  injury. 

Typical  attacks  of  Jacksonian  epilepsy  do  not  occur,  al-, 
though  general  convulsions  may  be  excited. 


THE  CORPUS  STRIATUM. 

Two  nodal  masses  of  gray  matter,  situated  within  the 
substance  of  each  cerebral  hemisphere,  have  been  referred  to 
in  previous  pages  as  the  *'  basal  ganglia."  They  appear,  from 
their  situation  and  relation  to  the  radiating  fibers  of  the  cere- 
brum (Fig.  7),  to  be  the  *' naturally  appointed  guardians" 
which  preside  over  all  impulses  -transmitted  to  or  from  the 
cerebral  cortex. 

Physiological  experiment  seems  to  point  clearly  to  an 
automatism  in  the  cells  of  these  masses,  exhibited  chiefly  in 
the  maintenance  of  equilibrium  after  the  hemispheres  have 
been  removed.  They  seem  also  to  exercise  some  discriminat- 
ing power  over  impulses  which  are  forced  to  pass  through 
them  when  the  hemispheres  are  called  into  action. 

From  an  anatomical  standpoint  these  bodies  seem,  as 
Luys  states,  to  be  the  "poles  around  which  the  nervous^ 
elements  of  the  cerebrum  gravitate";  and  to  constitute  "aJ 


THE  CORPUS  STRIATUM. 


123 


crown,  as  it  were,  to  the  fibers  of  the  crusta  and  tegmentum 
cruris  "  (Fig.  7). 

The  corpus  striatum  is  the  anterior  of  these  two  bodies ; 
and  the  fibers  which  are  apparently  associated  with  it  (the 
basis  cruris,  Fig.  8)  can  be  traced  into  the  antero-lateral 
columns  of  the  spinal  cord,  with  the  exception  of  those  that 
are  supposed  to  pass  to  the  cerebellum  through  the  medium 
of  the  pons.  It  may  be  considered,  therefore,  as  the  probable 
seat  of  modification  and  reinforcement  of  motor  impulses  ema- 
nating from  the  cerebral  cortex. 


Fig.  31. — Antero-posterior  vertical  section  of  the  right  hemisphere^  showing  the  cavity  of 
the  lateral  ventricle.     (After  Dalton.) 

C,  corpus  striatunr;  S,  surcingle  of  same;   Y,  ventricle;   A,  amygdala;   1,  internal  pa- 
rieto-occipital  fissure ;  2,  calcarine  fissure. 


In  the  fresh  brain  the  corpus  striatum  appears  as  a  reddish- 
gray  mass,  situated  in  front  of  the  optic  thalamus  in  each 
hemisphere  of  the  cerebrum.  Its  large  extremity  is  directed 
forward,  and  it  gradually  tapers  as  it  is  prolonged  toward 
the  posterior  lobes  of  the  brain.  It  is  abundantly  supplied 
with  capillary  vessels,  which  circulate  within  its  substance. 
The  extreme  softness  and  friability  of  the  mass  are  largely 
due  to  this  fact. 

We  know,  clinically,  that  the  larger  proportion  of  extra- 
nasations  of  blood  within  the  cerebral  hemispheres  affect  the 
corpus  striatum  ;  and  we  may  reasonably  attribute  the  greater 


124 

frequency  of  unilateral  paralysis  of  motion,  as  compared  with 
tliose  of  sensation,  possibly  to  this  abundance  of  vessels  and 
the  non-resistant  character  of  the  surrounding  brain-sub- 
stance. 

The  term  ^'corpus  striatum"  is  apparently  used  by  Allen, 
in  his  late  work  upon  anatomy,  to  cover  the  caudate  and 
lenticular  nucleus  an^  also  the  internal  capsule  of  the  cere- 
brum. Rosenthal  includes  the  caudate  nucleus  and  the  caudo- 
lenticular  portion  of  the  internal  capsule  under  this  term,  but 
he  treats  of  the  lenticular  nucleus  as  a  separate  ganglion. 
Meynert  applies  the  term  to  the  caudate  nucleus  alone.  Bu- 
ret divides  the  lenticular  nucleus  of  most  authors  into  two 
nuclei,  one  of  which  (the  posterior  or  brownish-red  portion) 
he  calls  the  ''lenticular  nucleus,"  and  the  remaining  portion 
the  "gray  nucleus,"  on  account  of  its  lighter  color. 

The  entire  mass  of  the  corpus  striatum,  when  viewed  after 
the  removal  of  the  hemispheres  by  a  horizontal  cut  made 
above  the  level  of  the  basal  ganglia,  presents  an  ovoid  pyri- 
form  appearance,  the  'larger  extremity  being  directed  toward 
the  frontal  lobe,  and  the  tapering  end  investing  the  optic  thal- 
amus (which  lies  behind  it)  as  a  layer  of  reddish-gray  mat- 
ter of  steadily  diminishing  thickness.  This  "tail-like"  pro- 
longation (the  Cauda)  has  been  described  by  Dalton '  (who, 
in  common  with  several  other  observers,  has  investigated  its 
peculiarities)  as  forming  a  complete  "surcingle"  to  the  thal- 
amus. Vertico- transverse  sections  of  the  hemisphere  of  the 
cerebrum,  made  to  include  the  thalamus  (as  shown  in  Fig.  15) 
reveal  two  cuts  of  the  caudate  portion,  an  upper  or  ventricu- 
lar portion,  and  a  lower  portion  which  is  perceived  in  the 
region  of  the  gyrus  hippocampus  (the  amygdala).  Such  a 
section  shows,  moreover,  that  the  so-called  "internal  cap- 
sule" of  the  cerebrum  divides  the  corpus  striatum  into  two 
distinct  parts ;  one  of  which  has  tliis  tail-like  prolongation 
and  projects  into  the  lateral  ventricle  (the  caudate  nucleus^ 
or  ventricular  portion),  while  the  other  is  shaped  somewhat 
like  a  section  of  a  lens,  and  lies  buried  within  the  substance 

*  Gratiolet,  Hirschfield,  and  Todd  confirm  this  view. 


THE  LENTICULAR  NUCLEUS.  125 

of  the  hemisphere  (the  lenticular  nucleus^  or  extra-ventricu- 
lar portion). ' 

The  caudate  and  lenticular  nuclei  become  fused,  however, 
both  anteriorly  and  posteriorly.  In  front,  the  caput  dips 
downward  toward  the  region  of  the  base  of  the  brain,  and 
becomes  fused  with  the  third  division  of  the  lenticular 
nucleus  (the  "olfactory  district"  of  Gratiolet).  Behind,  the 
Cauda  becomes  joined  to  the  temporal  process  of  the  third 
member  of  the  lenticular  nucleus  {pedunculus  nuclei  len- 
ticularis\  near  to  the  amygdala. 

Structurally  considered,  the  corpus  striatum  seems  to  be 
composed  of  nerve  cells  of  two  varieties :  one  being  of  large 
size  with  many  processes,  and  the  other  of  small  size  and 
multipolar."  The  small  cells  predominate  over  the  large  in 
point  of  numbers.  It  seems  probable  that  the  fibers  destined 
for  the  spinal  cord  are  associated  with  one  set  of  cells,  and 
those  to  go  to  the  cerebellum  with  the  other  (Luys) ;  but  this 
statement  is  as  yet  somewhat  conjectural,  although  Meynert 
believes  that  it  is  supported  by  anatomical  research. 

The  i^ucLEUs  LENTicuLARis  is  shaped  somewhat  like  a 
wedge,  its  base  being  directed  toward  the  frontal  lobe  and 
the  island  of  Reil,  while  its  point  passes  into  the  "crusta" 
(the  basis  cruris  of  Meynert),  and  terminates  posteriorly  in  a 
jagged,  thin  edge. 

If  a  section  through  its  substance  be  examined,  the  micro- 
scope will  show  the  existence  of  two  sets  of  nerve  fibers  within 
it,  viz.,  one,  whose  direction  corresponds  to  the  general 
course  of  its  longest  axis,  or  from  base  to  apex ;  and  a  second, 
which  runs  parallel  with  its  curved  base.' 

^  The  reader  is  referred  to  Fig.  32  and  other  diagrams  incorporated  in  the  text  of 
this  work. 

2  These  cells  vary  from  30  /t  to  15  /*  in  length.     ti=Twm  millimeter. 

^  The  fibers  of  the  lenticular  nucleus  which  run  parallel  with  the  curved  base  of  the 
wedge  separate  the  three  divisions  of  the  ganglion.  The  extra-ventricular  half  of  the 
corpus  striatum  must  be  regarded  as  connected  especially  with  the  fibers  which  arise  from 
the  island  of  Reil  and  other  parts  in  the  vicinity  of  the  walls  of  the  Sylvian  fissure.  Its 
form  suggests  that  the  frontal  and  parietal  lobes  furnish  by  far  the  greater  number  of  its 
fibers,  as  contrasted  with  the  temporal  and  occipital.  It  is  worthy  of  remark  that  the 
fibers  which  pass  through  this  ganglion  do  not  take  a  direct  course,  but  describe  compli- 
cated spiral  lines. 
11 


126  THE  BRAIN. 

The  second  set  divides  the  ganglion  into  three  distinct 
memhers  (Glieder),  the  external  being  the  thicker  and  larger, 
while  the  two  inner  are  the  richer  in  medullary  fibers,  which 
gives  them  the  name  of  '-^ globus  'pallidus^^  (Fig.  32). 

Within  the  substance  of  the  caudate  nucleus  (at  its  in-  * 
ferior  and  internal  portion),  there  exists  a  mass  of  yellowish 
colored  matter  to  which  the  name  '' yellow  nucleus  "  has  been 
applied  by  Luys.  In  it,  the  smaller  cells  of  this  ganglion  are 
described  as  being  very  abundant,  while  the  processes  given 
off  from  them  are  of  extreme  tenuity.  There  are  some, 
grounds  in  the  opinion  of  this  observer  for  the  theory  that 
these  smaller  cells  represent  the  cerebellar  elements  of  the 
ganglion  (Fig.  31)  while  the  large  cells  are  connected  with 
the  motor  nerves  of  the  projection  tract. 

Meynert  has  recognized  this  collection  of  nerve  cells, 
which  presents,  to  his  mind,  most  striking  peculiarities.  He 
locates  it  in  the  inferior  regions  of  the  caudate  nucleus,  ex- 
tending from  a  point  just  above  the  lamina  perforata,  an- 
terior to  the  neighborhood  of  the  so-called  anterior  corrir 
missure.  The  peculiar  anatomical  features  of  this  mass  are 
stated  by  this  author  to  consist  (1)  of  an  agglomeration  of 
small  nerve  cells  into  piles,  which  are  distinctly  circum- 
scribed ;  and  (2)  of  very  small  granules  (6  fi  in  diameter) 
packed  into  close  masses,  and  distinctly  isolated.  This  latter 
element  is  not  found  elsewhere  in  the  collective  cerebral 
ganglia,  and  is  believed  by  Meynert  to  indicate  a  structural 
relationship  between  the  caudate  nucleus  and  the  olfactory 
lobe. 

We  find  other  cells  in  the  corpus  striatum  in  addition  to 
the  two  varieties  of  nerve  elements  already  described,  those 
of  the  neuroglia;  but  they  are  of  little  if  any  importance 
(as  far  as  we  at  present  know)  from  a  physiological  or  clinical 
point  of  view. 

The  NERVE  FIBERS  ASSOCIATED  WITH  THE  CORPUS  STRI- 
ATUM may  be  divided  into  two  groups,  afferent  and  efferent. 

The  afferent  set  comprise  {a)  those  which  spring  from  the 
cortex  and  enter  the  substance  of  the  ganglion  ;  and  (6)  some 


CAUD0-8TRIATE  FIBERS.  127 

fibers  probably  connected  with  the  superior  peduncles  of  the 
cerebellum,  which  are  capable  of  being  traced  to  it. 

The  afferent  fibers  of  the  caudate  nucleus  may  be  traced  as 
^YQ  distinct  groups,  as  follows  : 

1.  Fibers  which  spring  from  the  entire  length  of  the  arch 
of  the  cerebral  hemisphere  {corona  radiata). 

2.  A  bundle  of  fibers  springing  from  the  cortex  of  the  tem- 
poral lobe  to  the  most  anterior  part  of  the  caudate  nucleus, 
following  a  curved  course  along  the  inner  border  of  that 
ganglion  {stria  cornea). 

3.  Fibers  which  arise  from  the  cortex  of  the  olfactory  lobe 
and  pass  to  the  corpus  striatum. 

4.  Fibers  which  unite  the  cortical  substance  of  the  sep- 
tum lucidum  with  the  inferior  region  of  the  corpus  striatum 
{pedunculus  septi  lucidi). 

5.  Fibers  of  the  cerebellum,  which  reach  the  cerebrum  as 
described  above. 

The  upper  border  of  the  caudate  nucleus  of  the  corpus 
striatum  which  is  at  the  same  time  its  outer.,  seems  to  be  the 
pole  toward  which  the  afferent  fibers  of  the  ganglion  center, 
with  the  exception  of  the  stria  cornea.  The  lower  or  inner 
border  acts  as  the  peripheric  pole,  from  which  its  efferent 
fibers  emerge. 

The  efferent  set  comprise  those  fasciculi  which  help  to 
form  the  cerebral  peduncle  (crus  cerebri),  and  which  are  dis- 
persed, after  having  passed  through  the  pons  Varolii,  chiefly 
in  the  different  segments  of  the  spinal  cord.' 

Let  us  now  consider  certain  points  in  the  arrangement  and 
probable  function  of  these  groups  of  fibers. 

The  afferent  fibers  which  spring  from  the  cortex  and  unite 
with  the  nerve  cells  of  the  corpus  striatum  may  be  designated 
as  the  "  cortico-striate  "  group.  They  appear  to  spring  chiefly 
from  the  psychic  (?)  and  motor  regions  of  the  cortex  ;  hence 
we  are  apparently  warranted  in  attributing  to  the  corpus 
striatum  some  special  association  with  these  two  functions. 
This  view  is,  moreover,  sustained  by  the  fact  that  the  efferent 

^  Some  of  the  efferent  fibers  of  the  corpus  striatum  probably  go  to  the  cerebellum. 


128 


THE  BRAIK 


fibers  of  this  ganglion  are  lodged  principally  in  the  motor 
paths  of  the  projection  system.' 

The  experiments  of  Fritsch  and  Hitzig  have  demonstrated 
that  weak  galvanic  currents  (when  applied  to  certain  regions 
of  the  cortex  apparently  connected  with  the  corpus  striatum 
by  radiating  fibers)  produce  muscular  movements  in  special 
regions  of  the  body ;  and  they  were  thus  enabled  to  create 
at  will  motions  of  the  eye,  tongue,  mouth,  neck,  and  limbs. 
Bartholow  has  demonstrated  the  same  physiological  result  in 
the  brain  of  a  man,  in  whom  the  top  of  the  skull  had  become 
destroyed  by  disease.  Both  Bourdon  and  Luys  have  discov- 
ered an  atrophy  of  cortical  motor  centers  (as  the  result  of  loss 
of  its  function)  in  subjects  deprived  of  a  limb  by  amputation. 
In  spite  of  these  facts,  however,  we  are  still  unable  to  state 
positively  that  all  the  fibers  which  radiate  from  the  motor 
centers  of  the  cortex  are  directly  united  with  the  nerve  cells 
found  in  the  corpus  striatum,  since  the  so-called  "internal 
capsule  " '  seems  to  pass  directly  through  the  ganglion  with- 
out meeting  any  interrupting  cell  elements  in  its  passage. 
Whether  this  is  actually  the  case  or  only  an  apparent  one, 
it  is  impossible  to  determine  from  our  present  knowledge. 
The  latest  investigations  of  Flechsig  seem  to  show  that  the 
so-called  "pyramidal  tracts"  are  independent  of  any  struct- 
ural relationship  with  the  cells  of  the  basal  ganglia. 

Among  the.  afferent  fibers  of  the  corpus  striatum,  I  have 
mentioned  certain  fibers  which  are  apparently  terminal  expan- 
sions of  the  superior  peduncles  of  the  cerebellum.  It  seems 
to  be  now  accepted  by  most  observers  that  the  fibers  of  these 
peduncles  first  decussate  in  the  median  line,  and  afterward 

*  A  term  first  brought  into  general  use  among  neurologists  by  MejTiert.  (See  page  41.) 

•  The  so-called  "  internal  capsule  "  separates  the  two  parts  of  the  corpus  striatum  in 
front,  and  the  lenticular  nucleus  from  the  optic  thalamus  posteriorly  (Fig.  15).  It  ex- 
tends into  the  crus  as  a  part  of  the  second  projection  system,  constituting  certain  motor 
and  sensory  tracts  found  within  the  "  basis  a-uris  cerebri "  and  the  "  tegmenium  cruris 
cerebri^  Within  the  crus,  those  fibers  which  are  connected  with  the  tail  of  the  intra- 
ventricular portion  of  the  corpus  striatum  are  described  by  Meynert  as  pursuing  a  some- 
what peculiar  course.  They  seem  to  appear  to  emerge  from  among  the  external  bundles, 
and  to  disappear  again  among  the  internal  fasciculi  of  the  crus.  To  reach  this  portion 
of  the  crus,  they  are  forced  to  cross  the  intermediate  bundles. 


FUKGTIOFS  OF  CORPUS  STRIATUM.  129 

become  associated  in  the  formation  of  two  masses  in  the  cms 
of  a  reddish  color  (red  nuclei  of  Stilling).  From  these  may 
be  traced  numerous  filaments  of  a  yellowish  color,  that,  after 
extensive  interlacement  with  each  other,  are  believed  by  Luys 
to  be  prolonged  to  the  yellow  nucleus  of  the  corpus  striatum. 
An  attractive  theory  has  been  advanced  by  Luys,  that  these 
delicate  fibrils  are  the  wires  which  carry  the  continuous  cur- 
rents of  electric  force,  which  overflow  from  the  cerebellum  to 
the  corpus  striatum,  and  thus  constantly  charge  the  cells  of 
that  body,  which  are  liable  to  become  exhausted  by  the  con- 
trolling influence  exerted  by  them  over  motor  impulses  trans- 
mitted from  the  cortex  of  the  cerebrum.  Physiological  ex- 
periment points  strongly  to  cerebellar  innervation  of  motor 
acts.  Disturbances  in  coordination  of  movement  are  pro- 
duced by  disease  of  the  cerebellum,  and  motor  acts  appear 
to  be  weakened.  These  phenomena  are  of  the  greatest  im- 
portance, as  they  tend  to  confirm  the  view  taken  by  Luys 
regarding  the  foci  of  motor  innervation. 

The  corpus  striatum,  like  the  optic  thalamus,  may  be  con- 
sidered, therefore,  "^  as  a  territory  in  which  cerebral^  cerebel- 
lar^ and  spinal  activities  are  brought  into  intimate  commu- 
nicationP  To  quote  the  opinion  of  Luys,  "  it  acts  as  a  halting 
place  for  voluntary  motor  impulses  emitted  from  the  cerebral 
cortex.  It  enables  these  impulses  to  become  modified  and 
possibly  reinforced  by  currents  derived  from  the  cerebellum  ; 
and,  by  its  efferent  fibers,  it  transmits  centrifugal  motor  im- 
pulses along  the  projection  system  to  different  groups  of  cells 
within  the  spinal  gray  matter,  whose  individual  functions 
they  tend  to  evoke." 

This  ganglion  probably  acts  as  '^a  condenser  and  modi- 
fier of  all  motor  acts  which  are  the  result  of  volition,  and 
manifests,  through  the  agency  of  its  satellites  (the  cells  of 
the  anterior  horns  of  the  gray  matter  of  the  spinal  cord), 
the  outward  expressions  of  our  personality."  Without  the 
influence  of  the  cerebral  hemispheres,  it  is  also  capable,  by 
means  of  cerebellar  innervation,  of  governing  all  the  complex 
muscular  movements  required  in  maintaining  equilibrium  (co- 


130 


THE  BRAIK 


ordinated  movements).  Finally,  it  may  be  presumed  to  pos- 
sess tlie  power  of  analysis  of  cerebral  and  cerebellar  currents 
received  simultaneously,  and  of  materializing  them  by  the  in- 
tervention of  its  nerve  cells,  projecting  them  in  a  new  form, 
amplified  and  incorporated  with  the  requirements  of  the  gen- 
eral organism. 


Efferent  fibers  of 
corpus  striatum. 


Fio.  82. — A  diagram  designed  by  the  autJior  to  show  the  afferent  and  efferent  fibers  of 

the  corpus  striatum. 

C,  Nj  "caudate  nucleus,"  or  ventricular  portion  of  corpus  striatum;  L,  JV,  "lenticular 
nucleus,"  or  extra-ventricular  portion  of  corpus  striatum ;  A-B,  median  line,  sepa- 
rating cerebral  hemispheres ;  P~F,  psycho-motor  regions  of  the  cortex ;  a,  pedun- 
cular fibers  connected  with  X,  N  ;  i,  fibers  of  the  so-called  "  internal  capsule  " ;  c, 
fibers  connected  with  C,  N;  0,  olfactory  fibers. 


FUNCTION'S  OF  CORPUS  STRIATUM.  131 

Experiments  made  upon  the  caudate  and  lenticular  nuclei 
can  hardly  be  said  to  have  afforded  results  which  can  be  made 
the  basis  for  positive  deductions  respecting  the  functions  of 
each.  Nothnagel  employed  injections  of  chromic  acid  into 
the  substance  of  each,  and  also  destroyed  them  by  means  of 
an  instrument  devised  for  that  purpose,  but  he  made  no  posi- 
tive conclusions  save  that  the  lenticular  nucleus  seemed  to 
have  a  more  decided  influence  upon  motion  than  the  caudate 
nucleus,  when  both  sides  were  simultaneously  destroyed. 

Some  observers  claim  to  have  removed  the  entire  ganglion 
without  any  marked  disturbance  of  sensory  or  motor  phe- 
nomena. Some  observations  in  comparative  anatomy  show  a 
relationship  between  the  caudate  nucleus  and  the  motor  fibers 
of  the  leg,  and  a  similar  relationship  between  the  lenticular 
nucleus  and  the  fibers  destined  for  the  arm. 

In  no  instance,  to  my  knowledge,  has  the  destruction  of 
either  of  its  two  nuclei  produced  psychic  effects.  When  aki- 
nesia (loss  of  movement)  has  been  thus  artificially  produced, 
it  seems  to  be  absolutely  confined  to  the  opposite  side  of  the 
body.  In  cases  of  extreme  rarity,  lesions  have  been  shown 
clinically  to  have  resulted  in  a  paralysis  of  motion  of  the  same 
side  ;  bat  Flechsig  has  helped  us  to  properly  interpret  these 
cases,  as  they  afford  evidence  of  an  indimdual  peculiarity  in 
the  relative  number  of  decussating  and  direct  pyramidal 
fibers.  Ferrier  has  produced  convulsive  movements  of  the 
opposite  side  of  the  body  by  faradism  of  the  corpus  striatum, 
and  Carville  and  Buret's  observations  seem  to  be  in  full  ac- 
cord, thus  sustaining  the  theoretical  view  first  advanced  by 
Carpenter  and  Todd,  as  to  an  exclusively  motor  function  in 
this  ganglion.  Burdon-Sanderson  also  has  produced  localized 
movements  by  electric  stimulation  of  the  white  matter  of  the 
brain  in  the  region  of  the  corpus  striatum.  Danilewsky  has 
observed  that  modifications  of  the  circulation  and  respiration 
were  produced  by  irritation  of  the  lenticular  nucleus;  and 
also,  to  a  slight  extent,  when  the  gray  matter  of  the  hemi- 
sphere overlying  this  nucleus  was  irritated.  It  is  extremely 
doubtful,  however,  if  these  effects  are  due  in  reality  to  local- 


TEE  BRAIN. 

ized  irritation,  because  the  fibers  of  the  cerebral  peduncle  are  ^ 
in  close  proximity.     The  removal  of  the  hemispheres  above       \ 
the  basal  ganglia  does  not  seem  to  affect  either  the  respiration       i 
or  the  circulation.  ^ 

It  vrould  be  rash  to  draw  any  conclusions  of  a  positive 
nature  in  the  face  of  such  a  conflicting  mass  of  experimental  i 
and  clinical  evidence.  It  can  not  be  disputed,  however,  that  j 
those  who  support  the  doctrine  that  the  fibers  of  the  internal  j 
capsule  are  the  direct  paths  for  motor  and  sensory  impulses,  ^^'^ 
and  that  all  effects  of  experiment  upon  or  disease  of  the  ; 
corpus  striatum  are  the  result  of  pressure  exerted  upon  this  ; 
tracts  have,  in  the  light  of  our  present  knowledge,  the  most  \ 
plausible  theory.  In  what  way  this  path  of  conduction  is  j 
brought  in  direct  or  indirect  dependence  upon  the  cell  €le-  wm 
ments  of  the  nodal  masses,  with  which  it  bears  so  intimate  a  1 
relation,  it  is  impossible  to  state  positively  ;  but  it  can  not  be  j 
denied  that  it  seems  to  have  the  power  of  isolated  conduction,  Sj 
in  spite  of  any  connections  with  ganglion  cells,  which  may 
yet  be  proved  to  exist. 

THE    OPTIC   THALAMUS. 

The  fibers  of  the  "  tegmentum  cruris  "  (Figs.  6  and  8)  are 
connected  chietiy  with  the  following  ganglia :  the  ^' optic  thala- 
mus''^\'  the  ^'corpus  quadrigeminum^'' ;  the  red  nuclei  of 
Stilling;  the  ''corpus  mamillare^^ ;  the  ''pineal  gland ^^  (co- 
narium) ;  and  a  ganglion  embedded  in  the  pons  Varolii.  The 
two  ganglia  first  named  have  a  connection  with  the  optic  tract, 
in  addition  to  a  connection  with  the  spinal  cord.  For  this 
reason,  the  "corpora  geniculata^^  may  be  considered  as  an 
appendage  to  them. 

Let  us  consider,  before  the  other  ganglia  are  touched 
upon,  the  peculiarities  in  arrangement  of  the  optic  thalamus 
and  its  probable  functions.' 

>  The  term  "  thalmmcephalon  "  is  sometimes  applied  to  the  thalamus,  pineal  gland, 
and  pituitary  body  when  collectively  considered.  These  may  be  considered  as  morpho- 
logically  related  to  each  other. 

*  The  ganglia  of  origin  of  the  tegmental  fibers  are  separately  considered  on  a  subse- 
quent page. 


d 


THE  OPTIC  THALAMUS,  I33 

This  ganglion  appears,  at  first  glance,  to  present  its  gray 
matter,  exposed  and  uncovered,  as  a  lining  to  the  third  ven- 
tricle. In  this  region,  a  band  of  white  fibers,  the  "stratum 
zonale^^^  defines  its  limits  and  separates  it  from  the  tail-like 
projection  of  the  corpus  striatum. 

When  the  gray  lining  of  the  ventricle  is  examined,  how- 
ever, it  becomes  evident  that  it  is  structurally  independent  of 
the  cells  of  the  optic  thalamus,  because  it  can  be  traced  as  a 
direct  continuation  of  the  central  tubular  gray  matter.  It  is 
in  reality  foreign  to  the  thalamus,  although  it  is  probably  con- 
nected with  nerve  fibers  which  penetrate  its  substance  in 
order  to  reach  certain  nuclei  of  the  central  gray  matter.  It 
will  be  described  in  detail  later. 

The  optic  thalamus,  as  well  as  the  corpus  quadrigeminum, 
is  poorly  developed  in  the  human  brain,  when  compared  with 
that  of  the  lower  animals.  In  shape,  it  has  been  compared 
by  Meynert  to  "an  arch  surrounding  a  transverse  axis";  in 
which  respect  it  bears  an  analogy  to  the  caudate  nucleus  of 
the  corpus  striatum,  and  the  general  arrangement  of  the  cere- 
bral hemispheres.  The  axes,  around  which  the  thalamus  ap- 
pears to  arch,  comprise,  according  to  Meynert,  the  brachia  of 
the  corpus  quadrigeminum  and  the  corpus  geniculatum  inter- 
num. The  greatest  breadth  of  the  thalamus  lies  posterior  to 
the  axis.  The  greatest  thickness  is  found  just  in  front  of  the 
axis.  At  its  anterior  extremity,  the  breadth  and  thickness 
attain  their  minimum. 

When  the  fornix  and  velum  interpositum  have  been  re- 
moved and  the  optic  thalami  are  viewed  from  above,  they 
appear  as  oval-shaped  masses  of  gray  substance  covered 
superficially  by  a  thin  layer  of  white  fibers.  A  longitudi- 
nal groove  (Fig.  33)  may  be  detected  on  the  superior  surface 
of  each,  which  inclines  slightly  inward  so  that  its  anterior 
extremity  approaches  the  mesial  plane.  It  terminates  before 
the  anterior  extremity  of  the  thalamus  is  reached.  This 
groove  is  caused  by  the  thickened  margin  of  the  fornix,  which 
extends  over  the  surface  of  the  thalamus  along  the  line  of  the 
groove.     The  anterior  part  of  the  thalamus  is  raised  into  a 


THE  BRAIN. 


Fia.  88. —  View  from  above  of  the  third  ventricle  and  a  part  of  the  lateral  ventricles,     j 

(Hcnle.) 

The  brain  has  been  sliced  horizontally,  immediately  below  th^  corpus  callosum,  and  the 
fornix  and  velum  interpositum  have  been  removed.  77io,  thalamus  opticus  ;  Ts,  its  I 
anterior  tubercle;  P«,  pulvinar;  Com,  middle  commissure  stretching  between  the  j 
two  optic  thalami  across  the  middle  of  the  third  ventricle ;  Cf,  cohimns  of  the  for-  i 
nix ;  CVi,  pineal  gland  projecting  downward  and  backward  between  the  superior  cor-  j 
pora  quadrigemina ;  Sf,  stria  terminalis ;  C\  nucleus  caudatus  of  the  corpus  stria-  j 
turn ;  Vsl,  ventricle  of  the  septum  lucidum  ;  CcP,  section  of  the  genu  of  the  corpus  ! 
callosum ;  Pen,  commencement  of  the  pineal  stria  or  peduncle,  T/o  ;  Cop,  posterior  j 
commissure.  wnf 

prominence,  the  so-called  ^'anterior  tubercle,''^  which  projects  j 
into  the  lateral  ventricle  and  is  covered  with  the  epithelial  ! 
lining  of  that  cavity.  It  lies  above  a  part  of  the  lenticular  \ 
nucleus,  as  may  be  seen  in  all  cross-sections  of  the  cerebrumUil 


'  The  anterior  tubercle  Is  farther  removed  from  the  level  of  the  base  of  the  cerebrum 
than  any  other  part  of  the  thalamus. 


d 


THE  OPTIC  THALAMUS.  I35 

At  the  posterior  and  inner  part  of  the  thalamus,  is  seen, 
as  in  front,  a  posterior  prominence  or  tubercle,  the  "pulvi- 
nary  This  projects  over  and  partly  conceals  the  brachia  of 
the  corpus  quadrigeminum. 

Below  and  external  to  the  pulvinar,  another  well-marked 
eminence,  the  ^^  outer  geniculate  hody^^^  m.2ij  be  seen,  which 
lies  external  to  and  above  the  ''inner  geniculate  hodyy 
These  two  eminences '  are  separated  by  one  of  the  roots  of  the 
optic  tract  (the  upper  hracMum).  The  optic  tract  arises  from 
this  brachium  and  the  two  geniculate  bodies,  and  curves 
downward  and  forward  around  the  crus  cerebri. 

Such  being  the  general  direction  and  shape  of  the  thala- 
mus, we  are  prepared  to  consider  the  arrangement  of  the 
fibers  which  are  connected  wdth  it.  It  presents,  in  the  first 
place,  three  blunt  pedicles,  which  become  united  with  some  of 
the  fibers  of  the  superior  projection  system  {corona  radiata). 
Those  fibers,  which  become  ultimately  united  with  these  blunt 
processes,  may  be  traced  to  the  cortex  of  the  frontal  lobe,  of 
the  walls  of  the  Sylvian  fossa,  and  of  the  temporo-sphenoidal 
lobe.  The  ganglion  is  also  in  intimate  relation  with  fibers 
which  radiate  to  the  cortex  of  the  occipital  and  parietal 
lobes. 

The  external  and  inferior  surfaces  of  the  thalamus  are 
not  free,  but  are  united  by  means  of  nerve  fibers  with  other 
parts  of  the  brain.  The  external  surface  lies  in  close  relation 
with  certain  fibers  of  the  "crusta,"  and  ''  tegmentum  cruris," 
which  pass  between  the  lenticular  nucleus  and  the  thalamus 
— those  forming  the  "internal  capsule"  of  the  cerebrum  (Fig. 
34).  The  inferior  surface  is  in  relation  with  the  crus ;  and, 
more  anteriorly,  the  corpus  albicans  and  the  tuber  cinereum 
lie  below  it. 

The  outlines  of  the  surfaces  of  the  thalamus  and  the 
lenticular  nucleus  of  the  corpus  striatum,  as  seen  in  all  verti- 
cal cross-sections  of  the  cerebrum,  may  be  roughly  compared 
to  the  form  of  a  square  whose  two  halves  are  defined  by  a 

'  These  bodies  are  discussed  more  in  detail  in  a  subsequent  page,  as  ganglia  of  origin 
of  tegmental  fibers. 


136 


TEE  BRAIN. 


diagnonal  band,  the  '^internal  capsule,'^^  running  from  the 
upper  and  outer  comer  to  the  lower  and  inner  corner.  These 
halves  correspond  to  the  respective  ganglia.      It  may  be 


FlO.  84. — Section  across  the  optic  thalaimis  and  corpus  striatum  in  the  region  of  tlie  middle 
commissure.    (Schafer,  after  a  preparation  by  Mr.  S.  G.  Shattuck.)    Natural  size. 

<A,  thalamus ;  a,  e,  t,  its  anterior,  external,  and  internal  nuclei  respectively ;  w,  its  lat- 
ticed layer ;  m.  c,  middle  commissure  ;  above  and  below  it  is  the  cavity  of  the  third 
ventricle ;  c.  c,  corpus  callosum ;  f,  fornix,  separated  from  the  third  ventricle  and 
thalamus  by  the  velum  interpositum.  In  the  middle  of  this  are  seen  the  two  veins 
of  Galen  and  the  choroid  plexuses  of  the  third  ventricle ;  and  at  its  edges  the  choroid 
plexuses  of  the  lateral  ventricles ;  t.  5.,  taenia  semicircularis ;  <t.,  forward  prolonga- 
tion of  the  crusta  passing  laterally  into  the  internal  capsule,  i.  c.  ;  s.  f.  r.,  subthalmic 
prolongation  of  the  tegmentum,  consisting  of  (1)  the  dorsal  layer,  (2)  the  zona  in- 
certa,  and  (3)  the  corpus  subthalamicum  ;  s.  «.,  substantia  nigra ;  n.  c,  nucleus  cauda- 
tus  of  the  corpus  striatum  ;  n.  ?.,  nucleus  lenticularis  ;  e.  c,  external  capsule ;  cl,  claus- 
trum  ;  /,  Island  of  Reil. 

worthy  of  remark,  in  this  connection,  that  the  surface  of  the 
thalamus  which  lies  in  contact  with  the  internal  capsule  of 
the  cerebrum  marks  the  central  or  receiving  pole  for  the  fibers 
which  join  it  with  the  cortex  of  the  cerebral  lobes.  This  is 
not  the  case  with  the  lenticular  nucleus,  as  has  been  stated  on 
a  previous  page.' 

The  external  surface  of  the  thalamus  (which  lies  in  contact 
with  the  internal  capsule  of  the  cerebrum)  presents  a  peculiar 
appearance,  which  has  given  it  the  name  of  "  lattice  layer " 
(Kolliker).  All  along  this  surface,  radiating  fibers  pass  out 
of  the  thalamus  to  become  intermingled  with  the  fibers  of  the 
internal  capsule,  and  to  be  subsequently  distributed  to  the 
cerebral  cortex.     Those  from  the  front  of  the  ganglion  pass 

*  See  pages  which  treat  of  the  Corpds  Striatum.  .  ^  ^ 


SURFACES  OF  THE  THALAMUS 


137 


to  the  frontal  lobe  ;  those  from  the  middle  are  distributed  to 
the  posterior  part  of  the  frontal  and  to  the  parietal  and  tem- 
poro- sphenoidal  lobes  ;  those  from  the  posterior  part  can  be 


Fig.  35. — Right  half  of  the  encephalic  peduncle  and  cerebellum  as  seen  from  the  inside 
of  a  median  section.     (Allen  Thomson,  after  Reichert.) 

II,  right  optic  nerve  ;  behind  it  the  optic  commissure  divided ;  III,  right  third  nerve ;  VI, 
sixth  nerve  ;  V^,  third  ventricle  ;  7%,l)ack  part  of  the  thalamus  opticus ;  H,  section  of 
the  pituitary  body ;  /?,  pineal  gland ;  below  its  stalk  is  the  posterior  commissure ;  ca, 
anterior  commissure  divided,  and  behind  it  the  divided  anterior  pillar  of  the  fornix ; 
Ic,  lamina  cinerea ;  «,  infundibnlum  (cavity) ;  /c,  tuber  cinereum  ;  behind  it  the  corpus 
albicans ;  /,  mark  of  the  anterior  pillar  of  the  fornix  descending  in  the  wall  of  the 
third  ventricle ;  cm^  commissura  mollis ;  s/9,  stria  pinealis,  or  peduncle  of  pineal 
gland  ;  Q,  lamina  quadrigemina ;  as,  aqueduct  of  Sylvius  near  the  fourth  ventricle ; 
c?',  crus  cerebri ;  Pw,  pons  varolii ;  J/,  medulla  oblongata ;  behind  these  the  cerebel- 
lum ;  1  to  2,  laminas  of  the  antero-superior  lobe ;  between  F*  and  1  are  seen  the 
lingnla  and  central  lobe  in  section;  3,  posto'io- inferior  lobe;  4,  lobtdus  gracilus ;  5, 
biventral  lobe ;  6,  amygdaloid  lobe. 

traced  to  the  temporo- sphenoidal  and  occipital  lobes.  From 
the  region  of  the  pulvinar,  or  posterior  tubercle,  fibers  can  be 
traced  into  the  optic  tract,  and  to  Munk's  visual  area  of  the 
cortex  of  the  occipital  lobes  (Wernicke).' 

*  Wernicke's  tract  of  fibers  pass  beneath  the  angular  gyrus  (in  which  Ferrier  places 
the  centers  of  vision)  but  terminates  in  the  cortex  of  the  occipital  lobe.  These  fibers  are 
shown  in  a  subsequent  cut  illustrative  of  the  optic  fibers. 


13g  TEE  BRATN-. 


The  lower  surface  of  tlie  thalamus  is  continuous,  posteri- 
orly, with  fibers  of  the  tegmentum  cruris  (the  subthalamic  \ 
tegmental  region)  \  in  front,  however,  this  prolongation  of  j 
fibers  inclines  to  the  outer  side  of  the  ganglion  and  becomes  i 
lost  in  a  layer  of  gray  matter  seen  in  the  floor  of  the  ventricle, 
which  corresponds  to  the  ''anterior  perforated  lamina^''  of  i 
the  base  of  the  brain.                                                                     ^\ 

The  lower  surface  of  the  thalamus  is  itself  prolonged,  an-  *  ^ 

teriorly,  into  a  tract  of  fibers  which  run  downward  and  out-  ; 

ward  into  the  white  substance  of  the  cerebral  hemisphere,  ] 
forming  the  so-called  ''lower  peduncle  of  the  thalamus. ^^  *    -^^'^i 

bundle  of  fibers,  the  "ansa  lenticular  is  ^^''  passes  underneath  ' 

the  thalamus  and  above  the  lower  peduncle  of  that  ganglion  i 

from  the  mesial  part  of  the  crusta  to  the  lenticular  nucleus.  I 

Between  these  two  tracts  of  fibers  gray  matter  is  interposed  ;  : 
the  three,  collectively  considered,  being  called  the  "substantia  .J 

innominata  of  Meiiy                                                                  *  i 

The  substance  of  the  thalamus  consists  of  nerve  fibers  and  j 

nerve  cells,  variously  disposed  ;  but  the  exact  arrangement  of  i 
each,  and  the  connections  of  the  nerve  cells  with  special  fibers, 

is  a  subject  for  much  future  investigation.     Many  of  the  \ 

theories  advanced  will  be  discussed  later.                                   ^^  '\ 

The  thalami    approach  each  other  very  closely   in  the  ■ 
median  line  ;  and,  slightly  forward  of  the  middle  of  the  third 

ventricle,  are  joined  by  a  band  of  gray  matter,  the  so-called  j 

" middle ^^  or  "soft  commissure''''  of  the  thalamus  (Fig.  34).  ; 
This  is  sometimes  double,  and  occasionally  is  absent.     It  is 

often  torn  across  in  removing  the  brain.     This  connecting  1 

band  is  composed  of  gray  matter.  j 

Not  more  than  one  half  of  the  actual  antero-posterior  meas- 
urement of  the  thalamus  is  exposed  in  the  third  ventricle. 

It  must  be  noted  that   the  anterior  tubercle  appears  in  the  \ 

lateral  ventricle  ;  and  that  the  pulvinar,  or  posterior  tubercle,  ■ 
lies  in  a  plane  posterior  to  that  which  would  intersect  the 

corpora  quadrigemina.     Note  also  that  the  anterior  commis-  i 

'  Meyncrt  claims  that  these  fibers  arise  from  the  cortex  of  the  fossa  of  Sylvius  and 

the  temporo-sphcnoidal  lobe.  ! 


FIBERS  OF  TEE  OPTIG  THALAMUS.  I39 

sure  of  the  third  ventricle  does  not  connect  the  optic  thalami, 
or  apparently  have  any  structural  relation  with  them.  The 
posterior  commissure  is  probably  a  continuation  of  the  com- 
missural fibers  of  the  fillet  {lemniscus),  which  pass  through 
the  substance  of  the  optic  thalami  and  diverge  in  the  cerebral 
hemispheres.  These  fibers  may,  in  part,  act  as  commissural 
fibers  between  the  thalami.  They  are  also  structurally  related 
to  the  pineal  gland. 

The  NERVE  FiBEES,  which  may  be  enumerated  as  inti- 
mately associated  with  the  structures  of  the  thalamus,  can  be 
divided  into  sets,  as  follows  : ' 

1.  Fibers  of  the  superior  projection  system  (p.  31),  which 
serve  to  unite  the  thalamus  with  the  cortex  of  the  frontal, 
parietal,  occipital,  and  temporo-sphenoidal  lobes,  and  the  fossa 
of  Sylvius. 

2.  Certain  fibers  which  can  be  traced  directly  into  the  optic 
tract,  thus  proving  some  functional  relationship  between  the 
thalamus  and  the  retina. 

'  The  system  of  nerve  fibers  that  exists  in  connection  with  the  thalamus,  according  to 
the  late  researches  made  by  Flechsig,  may  be  thus  summarized :  / 

1.  By  means  of  the  so-called  "  corona  radiata,"  the  thalamus  is  connected  with  all 
parts  of  the  cerebral  cortex. 

2.  Fibers  from  the  frontal  lobes  appear  to  be  associated  with  both  the  anterior  and 
outer  nuclei  and  the  stratum  zonale  of  the  thalamus.  They  reach  that  ganglion  by  means 
of  the  anterior  part  of  the  internal  capsule. 

3.  The  cortex  of  the  parietal  lobe  are  associated  with  the  outer  and  inner  nuclei  of  the 
thalamus  and  the  stratum  zonale. 

4.  The  cortex  of  the  occipital  lobe  is  associated  with  the  pulvinar  and  the  stratum 
zonale. 

5.  The  cortex  of  the  Sylvian  region  is  joined  to  the  outer  and  inner  nuclei  of  the 
thalamus  and  the  stratum  zonale. 

6.  The  cortex  of  the  hippocampal  region  is  connected  with  the  outer  nucleus  of  the 
thalamus  by  means  of  the  fornix,  after  its  fibers  have  first  passed  through  the  substance 
of  the  corpus  mammillare  and  turned  upon  themselves. 

7.  The  bundle  of  Vicq.  d'Azyr's  sends  fibers  to  the  fornix  and  also  some  to  the  reticu- 
lar formation  of  the  medulla,  passing  between  the  red  nucleus  of  the  tegmentum  and 
the  substantia  nigra. 

8.  The  so-called  "  Meynert's  bundle "  is  composed  of  fibers  that  spring  from  the 
stratum  zonale,  the  gray  lining  of  the  third  ventricle,  and  the  ganglion  of  the  habenula?. 
They  are  connected  with  the  ganglion  interpcdunculare,  but  can  not  be  definitely  traced 
into  the  reticular  formation  of  the  medulla. 

9.  Fibers  from  the  medullary  lamina  of  the  thalamus  pass  downward  to  the  red 
nucleus  and  the  gray  matter  adjacent  to  it.  They  probably  extend  to  the  cerebellum, 
but  they  can  not  be  traced  beyond  the  red  nucleus  of  the  tegmentum. 


140  ^  TEE  BRAIN, 

3.  Fibers  of  the  tegmentum  cruris  (Figs.  6  and  8),  wMch 
connect  the  thalamus  with  the  sensory  tract  of  the  spinal  cord- 
As  stated  in  a  previous  page,  these  are  to  be  classed  as  fibers 
of  the  middle  projection  system  (Meynert). 

At  the  upper  level  of  the  middle  point  of  the  thalamus, 
the  sensory  fibers  of  the  tegmentum  leave  the  internal  capsule 
to  radiate  toward  the  cortex.  This  has  been  termed  the  ' '  carre- 
feur  sensitif "  by  the  French  authors. '  Here  the  radiating 
fibers  that  escape  from  the  thalamus  become  intermingled  with 
the  sensory  capsular  fibers.  Flechsig  claims  to  have  been 
able  to  trace  the  sensory  tract  to  the  cortex  in  the  embryo, 
since  they  become  meduUated  at  a  later  period  than  do  the 
radiating  fibers  of  the  thalamus.  According  to  this  observer 
they  end  in  the  cortex  of  the  parietal  lobe,  behind  the  post- 
central gyrus. 

4.  It  is  claimed  by  Luys  that  the  anterior  tubercle  of  the 
thalamus  can  be  proved  to  be  directly  connected  with  special 
fibers  which  lead  to  regions  of  the  cortex  functionally  related 
with  the  olfactory  sense, 

5.  There  is  strong  clinical  evidence  to  be  adduced  in  sup- 
port of  the  view  that  the  sense  of  hearing  is,  in  some  imper- 
fectly understood  way,  connected  with  the  thalamus. 

FUNCTIONS   OF  THE   OPTIC   THALAMUS. 

Efforts  have  been  made  by  some  of  the  later  anatomists, 
who  have  specially  investigated  the  structure  of  the  brain,  to 
subdivide  the  gray  matter  of  the  thalamus  into  circumscribed 
masses  or  nuclei,  and  to  trace  the  fibers  which  appear  to  arise 
from  these  nuclei  to  special  regions  of  the  brain  and  spinal 
cord.  Among  the  most  attractive  of  these  attempts  may  be 
mentioned  that  of  Luys,  whose  views  will  be  subsequently 
given  in  detail.  Whether  clinical  research  and  physiological 
experiment  will  confirm  all  of  these  attractive  theories,  and 
place  them  upon  a  ground  as  worthy  of  credence  as  the  de- 
ductions of  Broca  and  Ferrier  regarding  the  functional  attri- 
butes of  other  parts  of  the  brain,  time  alone  can  decide. 

The  deductions  which  have  been  drawn  from  pathology  as 


FUNCTIONS  OF  TEE  OPTIC  THALAMUS.  141 

well  as  from  the  results  of  physiological  experiments,  made 
with  a  view  to  determine  the  functions  of  the  thalamus,  are 
apparently  contradictory  and  more  or  less  uncertain.  Paraly- 
sis of  motion  has  been  observed  to  follow  the  development  of 
a  lesion  confined  to  the  thalamus,  and  also  to  co-exist  with 
lesions  which  have  involved  the  corpus  striatum  and  the  thala- 
mus conjointly.  The  question  at  issue  is,  however,  whether 
the  thalamus  can  be  •shown  to  exert  any  positive  influence 
over  sensory  impulses,  and  whether  lesions  of  that  ganglion 
cause  impairment  or  loss  of  sensation.  Vulpian  observed  only 
impairment  of  motility  from  lesions  of  the  thalamus ;  Luys 
has  collected  cases  which  apparently  sustain  the  view  ad- 
vanced by  him,  viz.,  that  a  center  which  presides  over  gen- 
eral sensation  is  located  within  the  thalamus  ;  and  Crichton- 
Browne  has  also  collected  cases  where  a  diminution  or  aboli- 
tion of  sensation  has  been  observed  to  co-exist  with  lesions  of 
the  thalamus  of  the  opposite  hemisphere. 

Ferrier  reports  an  experiment  made  upon  a  monkey  which 
seems  to  sustain  the  view  of  Luys  and  Browne.  In  his  first 
operation,  the  expanding  stile tte  (which  was  pushed  into  the 
brain  with  the  intention  of  reaching  the  thalamus)  was  not 
inserted  far  enough,  and  no  marked  sensory  phenomena  fol- 
lowed ;  but,  when  the  instrument  was  subsequently  introduced 
through  the  same  tract  far  enough  to  reach  the  thalamus, 
tactile  sensation  was  thoroughly  destroyed.  In  reference  to 
this  experiment,  Ferrier  speaks  as  follows : 

''Without  for  the  present  attempting  to  estimate  how 
much  was  here  due  to  the  lesion  of  the  optic  thalamus  as 
such,  and  how  much  to  the  medullary  lesion  external  to  it, 
we  have  in  this  experiment  a  conclusive  proof  of  the  abolition 
of  cutaneous  sensation  by  an  injury  in  and  around  the  optic 
thalamus." 

Yeyssiere  has  shown  by  experiments  made  upon- dogs  that 
section  of  the  internal  capsule  in  the  region  of  the  thalamus 
causes  hemiansesthesia  of  the  opposite  side  of  the  body. 
Nature  has,  moreover,  verified  these  experiments  in  man, 
since  Turck,  Charcot,  and  others  have  clinically  observed  the 

12 


THE  BRAIN. 

same  effects,  as  the  result  of  disease  of  corresponding  regions. 
Unfortunately  for  science,  the  optic  thalamus  is  situated  at  a 
point  where  the  motor  and  sensory  tracts  have  not  as  yet  be- 
come very  clearly  differentiated  from  each  other.  Here  the 
two  appear  to  be  more  or  less  intermingled.  ^ 

We  have  reason  to  believe  that  the  cerebral  cortex  is 
brought  into  relation  with  all  the  organs  of  sense  by  means 
of  libers  which  pass  either  through  the*thalamus  or  the  pos- 
terior fibers  of  the  internal  capsule  of  the  cerebrum  which  lie 
adjacent  to  its  external  surface.  With  the  exception  of  the 
sense  of  smell,  there  is  no  other  medium  for  the  transmission, 
of  such  impulses  to  the  hemispheres.  '^ 

The  course  of  special  nerves  and  the  value  of  morbid 
phenomena  of  the  special  senses  will  be  discussed  later  in.y 
connection  with   the  internal  capsule,  the  corpora  quadri-  ^  ! 
gemina,  and  the  medulla.  \ 

According  to  the  researches  of  Luys,  four  isolated  gan-  -i 
glions  may  be  demonstrated  in  the  thalamus.  Arnold,  in 
common  with  some  other  anatomists,  has  recognized  three  of 
these,  and  the  fourth  is  now  added  by  the  author  quoted. 
This  author  states  that  these  ganglia  are  arranged  in  an  an- 
tero-posterior  plane,  and  form  successive  tuberosities  upon 
the  thalamus,  giving  that  body  the  appearance  of  a  conglom- 
erate gland  (Fig.  33.)  The  following  paragraphs  express  his 
views  relative  to  these  tuberosities :  -''^ 

The  anterior  ganglion  {corpus  album  suhrotundum)  is 
especially  prominent.  It  appears  to  be  developed  in  animals 
in  proportion  to  the  acuteness  of  the  sense  of  smell.'  By 
means  of  the  "  taenia  semicircularis,"  this  ganglion  (according 
to  Luys)  may  be  shown,  in  the  human  species,  to  be  connected 
with  the  roots  of  the  olfactory  nerve.     Respecting  it  he  says : 

'  The  late  researches  of  Fleehsig  and  also  those  of  Gudden  (the  former  of  whom  haa 
studied  the  relative  periods  of  development  of  the  main  nerve  tracts  of  the  brain,  while 
the  latter  has  studied  the  degenex'ative  chancres  that  follow  the  destruction  of  the  more 
LTiportant  tracts  in  newly-born  animals)  fail  to  show  any  direct  association  of  the 
olfactory  nerve  fibers  with  the  thalamus,  as  a  support  to  the  theoretical  view  of  Luys 
based  upon  clinical  data.  We  are  therefore  forced  to  believe  that  the  association  is  an 
indirect  one,  if  any  exists. 


LUYS'S  THALAMIC  CENTERS.  143 

*' Direct  anatomical  examination  shows  that  there  are  inti- 
mate connections  between  the  anterior  center  and  the  periph- 
eral olfactory  apparatus.  On  the  other  hand,  in  confirma- 
tion of  this,  in  the  animal  species,  in  which  the  olfactory 
apparatus  is  very  much  developed,  this  ganglion  itself  is  pro- 
portionally well  marked.  Analogy  has  thus  led  us  to  con- 
clude that  this  ganglion  is  in  direct  connection  with  the 
olfactory  impressions,  and  that  this  marks  it  as  the  point  of 
concentration  toward  which  they  converge  before  being  radi- 
ated toward  the  cortical  periphery." 

The  second  or  middle  center  is  in  apparent  continuity  with 
the  fibers  of  the  optic  tract.  It  may  therefore  be  considered, 
on  the  same  grounds  as  those  previously  quoted  respecting 
the  anterior  center,  as  a  seat  of  condensation  and  radiation  of 
visual  impressions. '  There  seemed  to  be  undisputable  grounds 
for  the  belief  that  the  external  geniculate  bodies^  the  superior 
corpora  quadrigemina,  and  the  pulmnar^  are,  in  some  way, 
also  associated  with  the  perceptions  afforded  by  the  retina. 
Moreover,  the  convolutions  of  the  occipital  lobes  may  be 
added  to  the  collections  of  gray  matter  previously  mentioned, 
since  physiological  experiment  tends  toward  that  view. 

Ritti  has  pointed  out  that  irritation  of  the  thalamus  may 
play  an  important  part  in  the  development  of  hallucinations. 

^V"e  know  that  extirpation  of  the  eye  is  followed  by  more 
or  less  comjDlete  atrophy  of  the  outer  geniculate  body  of  the 
opposite  side,  although  the  inner  geniculate  body  seems  to 
remain  unaffected.  The  experiments  of  Longet,  who  de- 
stroyed the  optic  thalami  upon  both  sides  without  being  able 
to  note  any  impairment  of  vision  or  influence  upon  the  move- 
ments of  the  pupil ;  and  those  of  Lussana  and  Lemoigne, 
who  found  that  blindness  of  the  opposite  eye  followed  uni- 
lateral destruction  of  the  thalamus,  may  suggest  the  possi- 
bility, in  the  experiments  of  the  former,  of  the  escape  of  this 
center  and,  in  those  of  the  latter,  its  destruction.  It  is  diffi- 
cult to  devise  any  experiment  which  will  positively  settle  the 

^  Luys  states  that  it  is  scarcely  visible  in  those  animals  (the  mole  as  an  example) 
where  the  optic  nerves  are  rudimentary. 


THE  BRAIN. 


bearings  of  the  thalamus  upon  vision  ;  because  it  is  almost 
impossible  to  destroy  special  portions  with  accuracy,  or,  if 
this  were  insured,  to  avoid  injury  to  adjacent  structures. 
Foumie  claims  to  have  effected  the  separate  annihilation  of 
the  special  senses  of  smell  and  vision  by  injections  made  into 
different  parts  of  the  thalamus  of  animals ;  and  his  experi- 
ments, if  subsequently  verified,  will  tend  to  confirm  some  of  .  ,i 
the  theories  advanced  by  Luys.  ■■^\ 


Fio,  36. — A  diagram  of  the  nuclei  of  the  optic  thalamus  and  the  converging  fibers 
sociated  with  them.      (Luys.) 

1,  converging  fibers  of  posterior  convolutions ;  2,  same,  of  middle  convolutions  ;  3,  same, 
of  anterior  convolutions ;  4,  4',  4",  cortical  periphery  as  related  to  the  central  gray 
masses ;  5,  optic  thalamus ;  6,  corpus  striatum ;  7,  anterior  {olfactory)  center ;  8, 
middle  {optic)  center;  9,  median  {sensitive)  center;  10,  posterior  {acoustic)  center; 
11,  central  gray  region;  12,  ascending  gray  fibers  of  visceral  innervation;  13,  gray 
optic  fibers;  14,  ascending  sensitive  fibers;  15,  ascending  acoustic  fibers;  16,  scries 
of  antero-lateral  fibers  of  the  spinal  axis  going  to  be  lost  in  the  corpus  striatum. 

The  third  center  ("  median  ganglion  "  of  Luys)  is  described 
as  about  the  size  of  a  pea,  and  situated  mathematically  in  the 
exact  center  of  the  thalamus.  To  it  the  discoverer  ascribes 
the  function  of  presiding  over  and  condensing  all  sensory 
impressions. 

The  fourth  or  posterior  center  is  stated  to  act  as  a  halting 


m 


I 


LESIONS  OF  OPTIC  THALAMUS,  145 

place  and  condenser  of  auditory  impressions.  Two  instances 
where  tlie  brains  of  deaf-mutes  w^ere  found  to  present  a  local- 
ized lesion  of  this  center  are  reported  by  Luys. 

The  views  here  expressed  are  quoted  on  account  of  their 
originality  ;  and  because  the  author  of  them  ranks  high  as  an 
authority  upon  the  subject  of  which  he  speaks. 

The  numerous  cases  of  cerebral  haemorrhage  which  have 
been  reported,  where  the  thalamus  w^as  apparently  the  seat  of 
localized  injury,  are  too  often  accompanied  with  a  clinical 
history  which  points  toward  pressure  upon  the  internal  cap- 
sule to  be  of  value  as  confirmatory  evidence  of  the  existence 
of  special  centers  in  the  thalamus.  The  effort  of  Luys  to 
adduce  cases  of  hemiansesthesia  in  support  of  his  views  re- 
garding the  function  of  the  '*  median  center"  of  the  thalamus, 
merely  because  a  lesion  of  that  ganglion  was  found  in  an  area 
defined  by  him  as  the  normal  limits  of  that  special  center, 
must  not  be  deemed  conclusive ;  because  the  same  effect 
might  have  been  produced  by  pressure  upon  the  posterior 
third  of  the  internal  capsule  of  the  cerebrum.  There  is  every 
reason  to  hope  and  possibly  to  believe  that  sooner  or  later 
isolated  ganglia  within  the  optic  thalamus  will  be  demon- 
strated to  exist  by  normal  and  pathological  anatomy  as  well 
as  by  physiological  experiment ;  but  the  conclusions  even  of 
so  prominent  an  author  should  not  be  fully  accepted  without 
further  testimony  to  substantiate  their  accuracy.  The 
anatomical  researches  of  Meynert  do  not  agree  with  the  con- 
clusions of  Luys. 

Some  interesting  cases  have,  however,  already  been 
brought  forward,  which  certainly  seem  to  sustain  the  views 
advanced  by  Luys.  A  case  reported  by  Hunter,'  where  a 
young  woman  successively  lost  the  senses  of  smell,  sight,  sen- 
sation, and  hearing,  and  who  gradually  sank,  remaining  a 
stranger  to  all  external  impressions,  disclosed  at  the  autopsy 
a  fungus  hsematodes  which  had  gradually  destroyed  the  optic 
thalamus  of  each  side,  and  the  optic  thalami  alone,  if  the 
drawing  given  is  reliable.     Again,  Fournie's  experiments  on 

*  "  Medico-chirg.  Trans.,"  London,  1825,  vol.  xiii. 


146  THE  BRAIK 

living  animals  point  strongly  to  the  existence  of  localized 
centers  in  the  thalamus.  Three  instances  of  unilateral  de- 
struction of  smell,  observed  by  Yoisin  and  reported  by  Luys, 
have  been  found  to  be  associated  with  a  destruction  of  the 
anterior  center  of  the  thalamus.  An  hemorrhagic  effusion  into 
the  thalamus,  on  a  level  with  the  soft  commissure  (the  situa- 
tion of  the  optic  center  of  Luys),  produced  (in  the  experience 
of  Serres)  a  sudden  loss  of  sight  in  both  eyes.  Kitti's  paper 
upon  the  effects  of  irritation  of  the  thalamus  upon  the  devel- 
opment of  hallucinations,  lends  strength  to  the  view  that 
that  ganglion  in  some  way  regulates  the  transmission  of  sen- 
sory impressions  of  all  kinds  to  the  cerebral  cortex  ;  and  con- 
firms the  opinion  that  "the  optic  thalami  are  to  be  regarded 
as  intermediary  regions  which  are  interposed  between  the 
purely  reflex  phenomena  of  the  spinal  cord  and  the  activities 
of  psychical  life." 

The  view  taken  by  Lussana  and  Lemoigne,  that  the  optic 
thalami  contained  motor  centers  in  animals  for  the  lateral 
movements  of  the  fore-limbs  of  the  opposite  side,  seems  to  be 
completely  overthrown  by  pathological  statistics  in  the  human 
race.  The  results  obtained  by  these  experimenters  are  also 
at  variance  with  the  belief,  which  has  now  become  general 
among  neurologists,  that  the  thalami  are  intimately  connected 
with  the  sensory  tracts  of  the  cerebrum  and  cord  ;  since  they 
concluded  that  no  evidence  of  pain  or  any  loss  of  sensibility 
resulted  from  injury  to  these  bodies. 

The  effects  of  all  experiments  on  animals,  however,  agree 
entirely  with  the  general  experience  of  pathologists,  that 
lesions  of  both  the  thalamus  and  corpus  striatum  produce  re- 
sults chiefly  upon  the  opposite  side  of  the  body ;  *  whether 
the  symptoms  produced  point  to  a  disturbance  of  the  kineso- 
dic  (motor)  or  sesthesodic  (sensory)  tracts.  The  view  originally 
advanced  by  Carpenter  and  Todd,  that  the  thalami  are  con- 
cerned in  the  upward  transmission  and  elaboration  of  sensory 
impulses,  in  contradistinction  to  the  corpora  striata,  which 

'  Rare  exceptions  to  this  rule  may  be  noted,  as  in  the  case  of  the  motor  strands 
(Flechsig). 


CENTRAL   TUBULAR   GRAY  MATTER.  147 

are  concerned  in  the  downward  transmission  and  elaboration 
of  motor  impulses,  seems  to  be  gaining  ground,  and  many 
facts  may  be  urged  in  its  favor. 

Wlien  the  cerebrum  is  removed  from  some  animals,  the 
frog  in  particular,  the  basal  ganglia  being  left  intact,  and 
some  oatward  excitation  be  afterward  used  to  induce  move- 
ment in  the  animal  so  mutilated,  there  is  every  indication 
that  the  animal  can  see,  because  it  avoids  objects  placed  be- 
fore the  eyes,  in  case  they  tend  to  obstruct  its  passage/  Its 
movements  are  those  of  an  entire  frog,  except  that  they  re- 
quire some  external  stimulus  to  call  them  forth.  It  can  be 
made  to  crawl,  jump,  croak,  swim,  and  perform  all  other  acts 
of  an  automatic  machine.  It  is  the  effect  of  light  upon  its 
movements,  however,  that  has  some  bearing  upon  the  exist- 
ence of  a  visual  center  within  the  substance  of  the  thalamus, 
since  no  observer  has  ever  demonstrated  that  the  corpus 
striatum  is  related  either  anatomically  or  physiologicalh^  with 
that  sense. 

THE   CEI^TRAL  TUBULAR   GRAY   MATTER   CONNECTED   WITH   THE   OPTIC 

THALAMUS. 

The  prolongation  of  the  gray  matter  of  the  spinal  cord, 
which  lines  the  third  ventricle,  is  best  described  in  connection 
with  the  thalamus,  although  it  is  structurally  independent  of 
that  ganglion.  The  following  parts  have  been  definitely 
made  out : 

1.  The  inferior  optic  ganglion.  This  mass  of  gray  matter 
is  situated  at  the  lateral  border  of  the  tuber  cinereum.  Mey- 
nerfc  and  Luys  describe  it  as  forming  an  integral  part  of  the 
tuber  cinereum,  although  Wagner  considers  it  as  a  part  of 
the  anterior  perforated  lamina.  It  presents  a  distinct  sickle- 
shaped  outline  on  longitudinal  sections,  the  concavity  of 
which  looks  forward.  Luys  thinks  that  the  two  ganglia  join 
in  the  median  line,  and  that  the  fibers  of  the  optic  nerve 
decussate  within  them.     The  opinion  of  Meynert  is  directly 

'  Such  an  animal  will  even  try  to  avoid  strong  shadows  thrown  by  the  sunlight  across 
its  path. 


148  ^^^^.  THE  BRAm. 

opposed  to  this  view.     This  author  advances,  moreover,  some' 
anatomical  grounds  for  the  belief  that  the  fibers  of  the  optic 
tract  really  belong  to  the  superior  projection  system  (analo- 
gous to  the  so-called  "radiating  fibers"  of  the  cerebrum) ;  that      ; 
the  inferior  optic  ganglion  is  to  be  regarded  as  the  peripheral      | 
extremity  of  these  fibers ;   and,  finally,  he  suggests  that  in      I 
some  undiscovered  way  the  fibers  will  probably  be  traced      ; 
later  to  some  nucleus  of  the  central  tubular  gray  matter  inti- 
mately connected  with  some  other  part  of  the  body,  perhaps  \J\ 
the  muscles  of  the  eye.     If  this  view  be  accepted,  the  super- 
imposed layers  of  the  retina  must  be  considered  as  analogous 
to  those  found  in  the  cortex  cerebri.  •  , 

2.  Within  the  tuber  cinereum,  behind  the  inferior  optic      i 
ganglion,  commissural  fibers  'which  turn  backward  within 
the  central  tubular  gray  matter  maybe  demonstrated.     The  .    i 
termination  of  these  fibers  is  as  yet  unsettled.  Hjji 

3.  The  posterior   longitudinal  fasciculus^  of  the  teg-  >^lj 
mentum   cruris   may  be   traced   along  the  central   tubular      \ 
gray  matter  of  the  third  ventricle,  the  aqueduct  of  Sylvius,       i 
and    the  fourth  ventricle.     It   terminates  centrally  in  the 
broad,  thin  ganglion  within  the   ^''substantia  innominata 
ofBeiV  ^,i 

From  this  ganglion,  fibers  may  be  traced  into  the  "  external  ; 
capsule  "  of  the  cerebrum,  the  cortex  of  the  operculum,  the  j 
fossa  of  Sylvius,  the  island  of  Reil,  the  claustrum,  and  cortex  ; 
of  the  temporo-sphenoidal  lobe.  The  greater  mass  of  the  gi 
posterior  longitudinal  fasciculus  of  the  tegmentum  lies  to  the  ■ 
outer  side  of  the  anterior  pillar  of  the  fornix,  but  a  few  fibers 
from  the  "  inf undibulum  "  pass  across  the  inner  side  of  the  ! 
pillar.  lS;j 

4.  The  descending  branch  of  the  anterior  pillar  of  the      ^ 
fornix  lies  within  the  central  tubular  gray  matter  of  the  third 
ventricle.     The  ascending  branch  is  also  similarly  imbedded       I 
before  it  enters  the  body  of  the  thalamus,  and  the  same  may    v 
be  said  of  the  upper  part  of  the  corpus  candicans  (mammil-  . ,  \ 

^  The  reader  is  referred  to  a  subsequent  page  for  the  complete  description  of  this 
bundle  of  fibers. 


ANTERIOR  PILLAR   OF  FORNIX. 


149 


lary  tubercle).  Luys,  Arnold,  and  Meckel  believe  that  the 
descending  branch  of  the  crus  of  the  fornix  becomes  fused 
with  the  stria  cornea  and  the  habenula  conarii.  The  crus  of 
the  fornix  makes  a  remarkable  twist  upon  itself,  the  loop 
of  which  forms  the  corpus  candicans  (mammillary  tubercle). 


Ant. Tubercle. 


peduncle  of 

pineal  dland.  j] 


lamina 
cinerea 


pulvin 


ar 


pineal 
10        ^lanci. 


Fig.  37. — A  diagram  designed  by  the  autlwr  to  sJiow  the  inner  surface  of  the  optic  thala- 
mus^ ivith  the  tuhidar  gray  matter  removed^  showing  the  third  ventricle^  and  the  ar- 
rangement of  neighboring  parts. 

Th.  sup..,  superior  part  of  thalamus;  Th.  inf.,  inferior  part  of  same;  m.  c,  middle  com- 
missure; 1,  section  of  optic  commissure;  2,  infundibulum  and  pituitary  body;  3, 
anterior  commissure  of  third  ventricle ;  4,  anterior  crus  of  fornix ;  5,  corpus  can- 
dicans (mammillary  tubercle) ;  6,  bundle  of  Vicq  d'Azyr ;  7,  the  third  nerve ;  8,  crus 
cerebri;  9,  pons  Varolii;  10,  posterior  commissure;  11,  corpora  quadrigemina ;  12, 
aqueduct  of  Sylvius;  13,  fourth  ventricle;  14,  third  ventricle.  This  cut  should  be 
compared  with  Fig.  3,  in  which  the  gray  lining  of  the  ventricle  is  intact. 

when  it  reaches  the  base  of  the  brain,  and  returns  to  enter 
the  substance  of  the  thalamus  (bundle  of  Yicq  d'Azyr).'  It 
must  not  be  inferred,  however,  that  the  corpus  candicans  con- 
sists only  of  fibers  of  the  fornix,  doubled  upon  themselves ; 

.-a 
'  Forel  and  Gudden  deny  that  the  fibers  of  the  anterior  pillars  of  the  fornix  are 
directly  continuous  with  those  of  the  bundle  of  Vicq  d'Azyr. 


THE  BRAm. 


as  nerve-cells  are  abundant  within  it,  some  of  which  are  ii3|i 
intimate  relation  with  the  fibers  of  the  eras  fornicis.  •'9| 

It  will  be  apparent,  after  w^hat  has  been  said,  that  the     '-. 
lining  of  the  third  ventricle  represents  a  prolongation  of  the     i 
gray  substance  of  the  spinal  cord  into  the  brain.     By  Luys     , 
it    is  considered  as  connected  with    fibers   imbedded  both 
within  it  and  the  thalamus,  which  concentrate  themselves 
around  certain  nodal  points,  among  which  he  mentions  the    ^i 
"gray  protuberances  of  the  septum,  for  the  olfactory  roots ; 511 
those  of  the  tuber  cinereum,  for  the  optic  fibers  ;  the  mamil-     ; 
lary  tubercles  and  pineal  gland,  for  the  connecting  fibers 
emanating  from  the  anterior  centers."     He  also  says,  "It     \ 
similarly  receives   a  certain  contingent  of  gray  ascending     | 
fibers,  which  probably  represent  the  centripetal  spinal  fibers     j 
which  are  distributed  to  these  plexuses."  ^ 

It  is  probable,  and  by  some  authors  stated  to  be  demon-^    I 
strable,  that  all  of  the  cerebral  fibers,  apparently  distributed     \ 
to  the  substance  of  the  thalamus,  are  not  connected  with  the 
nerve-cells  of  that  ganglion.     Some  unquestionably  appear     j 
to  pass  through  it  to  become  united  with  the  gray  masses     ; 
described  as  connected  with  the  lining  tubular  gray  matter  of 
the  third  ventricle.     In  this  way  the  thalamus  possibly  be-C-: 
comes  indirectly  associated  with  the  gray  substance  of  the     ' 
spinal  cord  as  well  as  with  the  sensory  tracts  comprised  with- 
in the  'tegmentum  cruris.'     It  is  from  this  standpoint  that     j 
Luys  expresses  himself  as  follows  :  '!i. 

''From  this  double  induction  we  are  therefore  led  to  con-  ; 
sider  the  masses  of  gray  matter  usually  described  under  the  ; 
name  of  '  optic  thalami,'  as  essentially  central  regions  which  i 
are  the  bond  of  union  between  the  various  elements  of  the? 
entire  cerebral  system.  ; 

"  Through  their  tissues  pass  vibrations  of  all  kinds — those 
which  radiate  from  the  external  world,  as  well  as  those  which 
emanate  from  vegetative  life.  There,  in  the  midst  of  their 
cells,  in  the  secret  chambers  of  their  peculiar  activity,  these ;? 
vibrations  are  diffused,  and  make  a  preparatory  halt ;  and 
thence  they  are  darted  out  in  all  directions,  in  a  new  and 


U 


THE  INTERNAL    CAPSULE.  151 

already  more  animalized  and  more  assimilable  form,  to  afford 
food  for  the  activity  of  the  tissues  of  the  cortical  substance, 
which  only  live  and  work  under  the  impulse  of  their  stimu- 
lating excitement." 

THE    INTERNAL    CAPSULE    OF    THE    CEREBRUM    AND    THE 
DIAGNOSIS    OF    LESIONS    AFFECTING    IT. 

In  connection  with  the  description  of  the  so-called  basal 
ganglia  (the  ''corpus  striatum "  and  "optic  thalamus "  of  each 
hemisphere),  I  have  repeatedly  mentioned  a  tract  of  fibers, 
called  the  "internal  capsule  of  the  cerebrum "' (Figs.  7  and 
12).  This  band  has  an  anatomical  peculiarity,  which  has 
brought  it  into  prominence  with  both  physiologists  and 
neurologists,  viz.,  that  it  seems  to  trar^erse  the  substance  of 
the  basal  ganglia  without  any  apparent  structural  relation 
with  the  nerve-cells  found  within  them.'' 

It  is  by  no  means  certain  that  the  nerve-cells  referred  to 
may  not,  in  some  indirect  manner,  be  yet  proved  to  modify 
or  govern  the  impulses  which  travel  along  the  fibers  of  the 

'  Properly  speaking  this  band  of  fibers  should  be  named  the  "  internal  capsule  of  the 
lenticular  nucleus.'^'' 

2  The  late  researches  of  Flechsig  tend  to  prove  that  a  direct  communication  exists 
between  the  motor  area  of  the  cerebral  cortex  and  the  spinal  cord,  without  any  interven- 
tion of  the  cells  composing  the  basal  ganglia.  The  so-called  "  pyramidal  tracts  "  have 
been  traced  by  this  observer  (1)  through  the  middle  third  of  the  internal  capsule  (pos- 
terior to  the  "  knee  ") ;  (2)  through  the  median  part  of  the  motor  half  of  the  crus  ;  and 
(3)  as  two  strands,  one  of  which  decussates  and  the  other  as  a  direct  bundle,  in  the 
medulla. 

The  non-decussating  or  direct  bundle  is  continued  into  the  cord  as  the  so-called 
*■'■  column  of  Titrck,''^  or  the  "  direct  pyramidal  column?"*  The  decussating  bundle,  which 
is  much  larger  than  the  direct,  is  prolonged  into  the  spinal  cord  after  crossing  to  the 
opposite  side  of  the  medulla,  as  the  so-called*"  crossed  pyramidal  column.''^  It  occupies  a 
distinct  area  in  the  lateral  column  of  the  spinal  cord  whose  position  changes  somewhat 
at  different  altitudes.  Finally,  the' pyramidal  tracts  are  found  to  give  off  fibers  to  the 
anterior  ganglionic  cells  of  the  spinal  gray  matter,  chiefly  in  the  cervical  and  lumbar  en- 
largements of  the  cord.  In  this  way  they  connect  the  brain  with  the  motor  cells — chiefly 
those  associated  with  the  muscles  of  the  extremities,  in  contradistinction  to  those  of  the 
trunk. 

The  method  of  arrangement  of  the  fibers  of  the  internal  capsule,  when  the  level  of 
the  crusta  is  reached,  seems  to  be  comparatively  uniform.  Those  that  spring  from  the 
motor  regions  of  the  cortex  pass  down  the  median  part  of  the  crusta ;  those  composing 
the  "  genu  "  or  knee  of  the  internal  capsule  pass  through  its  central  part ;  some  from  the 
posterior  portion  of  the  capsule  lie  in  the  lateral  part  of  the  crusta. 


152 


THE  BRAIK 


internal  capsule  (as  we  have  every  reason  to  believe  they  do 
in  the  case  of  other  fibers  which  pass  from  the  cortex  to  the 
crus,  pons  Varolii,  and  spinal  cord) ;  but,  at  present,  we  are 
compelled  to  admit  that  this  region  appears  to  afford  the 
only  direct  communication  between  the  convolutions  and 
parts  below  the  cerebrum,*  because  any  intervention  on  the 
part  of  the  corpus  striatum  or  the  optic  thalamus  has  not 
been  conclusively  demonstrated. 


Fia.  38. — A  diagram  designed  hy  the  author  to  show  the  relation  of  the  internal  cap- 
sule of  the  cerebrum  to  adjacent  structures  viewed  from  above. 

The  section  of  the  brain  has  been  made  horizontally  in  a  plane  to  intersect  the  basal  gan- 
glia, C.  N.,  caudate  nucleus  of  corpus  striatum  ;  L.  N.,  lenticular  nucleus  of  the  same 
with  its  three  parts  (a,  6,  c);  0.  T.,  optic  thalamus;  S,  fossa  of  Sylvius;  C,  claus- 
trum ;  E.  C,  external  capsule  of  cerebrum ;  «,  i,  «,  convolutions  of  the  Island  of 
Reil ;  a,  b,  c,  the  inner,  middle,  and  external  member  of  the  lenticular  nucleus ;  1, 
anterior  limit  of  the  internal  capsule ;  2,  "  knee  "  or  bend  of  the  same ;  3,  posterior 
limit  of  the  same ;  1-2,  "  caudo-lenticular  "  portion  of  the  capsule  ;  2-3,  "  thalamo- 
lenticular "  portion  of  the  same ;  F,  crura  of  fornix,  the  fifth  ventricle  lying  in  front, 
and  the  third  ventricle  behind  it ;  s.  /.,  septum  lucidum,  showing  its  two  layers  with 
fifth  ventricle  between  them ;  m.  c,  middle  commissure  of  the  thalamus ;  /),  pineal- 
gland  and  its  peduncles ;  w,  nates  cerebri ;  <,  testes  cerebri. 

This  tract  seems  to  be  a  continuation  upward  of  both  the 
motor  and  ^^Ti^or^  portions  of  the  crus  (the  ''basis  cruris," 
and  ''tegmentum  cruris,"  of  Meynert)  into  the  white  sub- 
stance of  the  cerebral  hemisphere  of  either  side,  where  its 
fibers  diverge  and  pass  to  the  convolutions.     It  forms  the 

'  The  fibers  of  the  "  external  capsule  of  the  cerebrum  "  may  be  an  exception  (Fig.  1). 


y2:^ 


THE  INTERNAL   CAPSULE.  I53 

greater  part  of  the  so-called  '' corona  radiata,"  which,  were 
described  in  a  previous  page ;  although,  properly  speaking, 
the  internal  capsule  ceases  at  the  optic  tracts  below  and  the 
upper  level  of  the  lenticular  nucleus  above.  If  we  trace  the 
anterior  fibers  of  this  bundle  from  below  upward,  we  shall  see 
that  it  divides  the  corpus  striatum  of  each  hemisphere  into 
its  two  portions,  the  caudate  and  lenticular  nuclei.  The  pos- 
terior fibers  of  the  internal  capsule  separate  the  lenticular 
nucleus  from  the  optic  thalamus  of  the  corresponding  side 
(Fig.  38).  The  diagram,  to  which  I  now  direct  your  atten- 
tion, will  make  the  relations  of  this  bundle  apparent,  while 
it  will  also  show  the  peculiar  angle  or  bend  which  the  in- 
ternal capsule  exhibits  in  all  horizontal  sections  of  the  brain 
which  intersect  the  basal  ganglia.  The  fibers  that  form  the 
^'caudo-lenticular "  portion  of  the  capsule  are  imperfectly 
understood.  We  have  no  positive  evidence  of  their  motor 
function.  The  pyramidal  tract  lies  posterior  to  the  '^genu" 
of  the  capsule,  as  do  also  ^the  motor  fibers  of  the  face.  Back 
of  these  tracts  we  encounter  the  general  sensory  tracts.  The 
optic  fibers  appear  to  lie  still  farther  back,  passing  to  the 
occipital  cortex  (see  Fig.  39). 

Again,  if  a  cross  vertical  section  of  the  cerebral  hemi- 
spheres be  so  made  as  to  include  the  substance  of  the  thala- 
mus and  the  lenticular  nucleus,  it  will  be  perceived  that  the 
peripheral  outline  of  these  two  masses  of  gray  matter  may 
be  compared  to  a  square ;  and  that  a  diagonal  band  running 
from  the  outer  and  upper  corner  to  the  lower  and  inner  cor- 
ner of  this  square  corresponds  to  the  situation  of  the  ''in- 
ternal capsule,"  which  is  included  between  these  ganglia. 
Above  the  level  of  the  basal  ganglia,  the  fibers  of  the  internal 
capsule  radiate  to  join  certain  convolutions  or  "gyri"  which 
will  be  enumerated  later.  Thus  it  is  that  the  fibers  which 
compose  the  internal  capsule  appear  in  most  of  the  cross- 
sections  of  the  middle  zone  of  the  cerebrum  to  bear  a  fancied 
resemblance  to  the  handle  and  sticks  of  a  Japanese  fan  ;  the 
handle  being  the  constricted  portion  between  the  corpus 
striatum  and  the  optic  thalamus,  or  the  capsule  itself,  and 


154 


THE  BRAIN. 


J 

the  diverging  fibers  being  located  within  the  medullary  center;^^ 
of  the  cerebral  hemisphere.  •  wj 

The  extension  of  sensory  fibers  from  the  tegmentum  cruris  i 
upward  within  the  internal  capsule  of  the  cerebrum  is  now  as  \ 
clearly  proved  as  is  the  continuity  of  the  motor  tract  anteri-  \ 
orly.     The  course  of  the  former  has  been  studied  by  dissec-cy  j 


Fig.  39.—^  diagram  designed  by  the  author  to  shoio  the  svhdivisions  of  the  internal 

capsule. 

a,  the  portion  which  lies  anteriorly  to  the  knee  of  the  capsule.  The  functions  of  thei 
fibers  which  compose  this  portion  are  not,  as  yet,  definitely  determined.  /,  the 
fibers  for  the  face ;  m,  the  fibers  of  the  so-called  "  motor  tract " ;  s,  those  of  the 
"sensory  tract";  s,  f,  those  of  the  "speech  tract";  o,  those  of  the  "optic  tract." 
■  The  fibers  of  each  tract  are  probably  associated  with  both  sides  of  the  body,  but 
chiefly  with  the  opposite  side. 

tion,  embryological  investigation,  physiological  experiment, 
and,  finally,  by  the  examinations  of  pathological  processes. 
It  has  been  shown  by  Turck '  that,  when  certain  convolutions 
of  the  brain  (chiefly  those  which  are  motor  in  function)  have 
suffered  partial  or  complete  destruction,  that  a  descending/ ' 
defeneration  follows  the  course  of  the  nerves  which  are  con- 


^^ 


^  This  author  first  made  known  his  great  discovery  to  the  Academy  of  Sciences  of: 
Vienna,  in  1851. 

*  Degeneration  of  nerves  follows,  as  a  rule,  the  direction  of  the  currents  which  are 
normalbj  conveyed  hy  thrm.  By  this  means,  the  question  of  the  afferent  or  efferent 
character  of  certain  nerve-tracts  has  been  positively  decided. 


1 


d 


METHODS  OF  TUECK  AND  WALLER.  155 

nected  with  tlie  cells  of  the  injured  part.  This  degenerative 
process  extends  along  the  nerves,  from  the  cells  of  the  cortex, 
to  their  peripheral  terminations,  in  the  cells  of  the  spinal 
gray  matter;  thus  enabling  a  careful  observer  to  trace  the 
paths  of  the  fibers  with  even  greater  accuracy  and  positive- 
ness  than  the  most  skillful  dissector  could  possibly  hope  to 
attain.  By  means  of  this  fact,'  amplified  somewhat  by 
Waller  and  Gudden,  physiologists  have  been  enabled  to  solve 
many  problems  regarding  the  origin  and  course  of  special 
nerves,  as  well  as  certain  nerve- tracts  within  the  spinal  cord 
and  brain,  which  could  not  otherwise  have  been  determined. 

Although  the  remarkable  observations  of  Turck  were 
given  to  the  profession  some  years  before  Waller  was  awarded 
the  honor  of  meriting  recognition  as  the  recipient  of  the 
Moynton  Prize  for  Experimental  Physiology,  his  paper  re- 
mained comparatively  unknown  for  some  years,  when  its 
great  value  at  last  became  recognized. 

The  difference  between  the  discoveries  of  Waller  and 
Ttirck  lie  in  the  fact  that  the  observations  of  the  former  were 
confined  to  the  results  of  artificial  section  of  spinal  nerxes, 
made  for  the  purpose  of  studying  the  effects  of  such  injuries, 
while  those  of  Tiirck  were  of  a  purely  pathological  character, 
in  which  the  results  of  old  morhid  deposits  within  the  sub- 
stance of  the  brain  were  studied  by  the  aid  of  successive  sec- 
tions of  the  brain  and  spinal  cord  at  different  levels,  which 
could  be  contrasted  with  each  other. 

Both  of  these  observers  arrived  at  the  same  fundamental 
law,  viz.,  that  injuries  of  nerves  or  of  nerve- tracts  which  sep- 
arated them  from  their  centers  of  nutrition  or  trophic  centers, 
cause  a  degenerative  process  which  extends  along  the  sepa- 
rate nerve-fibers  to   their  ultimate  ramifications.  *"    Waller's 

^  The  reader  is  referred  to  a  lecture  upon  the  "  Wallerian  Method  of  Research,"  by 
Prof.  Dalton,  "Med.  Record,"  Feb.  11,  1882. 

^  Nerve-fibers  degenerate  only  when  severed  from  their  connection  with  some  special 
nerve-center,  from  which  they  receive  their  nutrition.  These  are  called  the  "trophic 
centers  "  of  the  different  bundles.  When  once  cut  off,  the  degenerative  process  extends 
throughout  the  entire  length  of  the  nerve ;  unless  it  meets  another  nerve-center  (some 
ganglionic  mass  of  gray  substance)  interposed  in  its  course.  It  seldom,  therefore,  if  ever, 
extends  from  spinal  nerve-tracts  into  the  spinal  nerves,  or  vice  versa. 


15< 


THE  BRAIK 


experiments  were  confined  exclusively  to  the  spinal  nerves, 
and  resulted  in  the  following  deductions  :  1,  That  if  the  nerve 
was  divided  at  its  exit  from  the  vertebral  canal,  all  of  its  ulti- 
mate fibers  degenerated  for  its  entire  length ;  2,  that  if  the 
anterior  root  of  the  nerve  was  alone  divided,  only  the  motor 
fibers  degenerated ;  3,  that  if  the  posterior  root  of  the  nerve 
was  severed  outside  of  its  ganglion,  the  sensory  fibers  of  the 
nerve  degenerated  and  the  motor  fibers  remained  unaffected  ; 
4,  that  if  the  posterior  root  was  divided  internal  to  its  gan- 
glion^ the  nerve  outside  of  the  ganglion  did  not  degenerate, 
but  the  portion  which  was  still  attached  to  the  spinal  cord, 
but  separated  from  the  ganglion,  suffered  complete  degenera- 
tion. From  these  data,  this  observer  was  enabled  to  lay  down 
the  general  law  that  the  motor  fibers  of  the  spinal  nerves  are 
dependent  for  their  structural  integrity  upon  their  connec- 
tion with  the  spinal  cord^  while  the  sensory  nerve-fibers 
depend  upon  their  connection  with  the  spinal  ganglia.         ^' 

The  degenerative  process  which  was  recognized  by  both 
Tiirck  and  Waller  consists  in  the  segmentation  of  the  myelin 
and  the  production  of  an  excess  of  nuclei  along  the  course  of 
the  affected  nerve-fibers.  The  unaffected  fibers  retain  their 
normal  appearance,  and  thus  define  the  diseased  bundles  so 
that  they  can  be  traced  along  the  spinal  cord  and  peripheral 
nerves  with  great  accuracy. 

Tiirck  was  enabled  to  demonstrate  for  the  first  time  a  dis- 
tinction between  the  anterior  and  posterior  segments  of  the 
lateral  column  of  the  spinal  cord,  which  no  ordinary  dissec- 
tion could  possibly  have  established.  The  observations  of 
Tiirck. have  been  supplemented  by  those  of  Gudden,  Goltz, 
Gull,  Flechsig,  Meynert,  Rolando,  Stilling,  Foville,  Gratiolet, 
Broadbent,  Bourdon,  Charcot,  Spitzka,  Starr,  and  others,  who 
have  added  much  to  our  knowledge  of  the  situation  and  func- 
tions of  the  various  spinal  nerve- tracts. 

Gudden'' s  method  of  anatomical  research  consists  in  the 
destruction  of  nerve-tracts  by  operations  performed  upolBL 
newly -born  animals.     He  found  that,  as  a  result  of  the  injury 
done,  the  proximal  end  of  the  divided  nerve  atrophied^  as^ 


METHODS  OF  GULDEN  AND  FLECHSIG.  I57 

well  as  the  central  connections  of  the  nerve.  The  so-called 
Wallerian  degeneration,  of  course,  affects  the  distal  portion 
of  the  nerve,  simultaneously  with  the  development  of  Gud- 
den's  degeneration  of  the  proximal  portion. 

Flechsig'  s  method  consists  in  studying  the  relative  period 
(during  fetal  development)  at  which  certain  nerve-strands 
acquire  myelin. 

Thus  we  have  to-day  the  older  methods  (1)  of  actual  dis- 
section of  nerve-bundles  in  partially  hardened  specimens,  and 
(2)  the  comparison  of  a  consecutive  series  of  fine  sections  of 
the  brain  and  spinal  cord  with  each  other,  supplemented  by 
the  more  accurate  methods  of  Tiirck,  Gudden,  and  Flechsig, 
as  guides  in  our  anatomical  studies  of  the  nervous  system. 

The  study  of  microcephalic  brains,  although  yet  in  its 
infancy,  bears  evidence  of  affording  grekt  possibilities  in  the 
future  toward  the  elucidation  of  disputed  points  in  cerebral 
and  spinal  anatomy.  M.  Allen  Starr  has  lately  reported  a 
very  interesting  case  of  this  character. 

The  fibers  of  the  caudo-lenticular  portion  (Fig.  38)  are  prob- 
ably deflected  (in  the  pons)  and  pass  to  the  cerebellilm.  The 
remaining  fibers  which  lie  anteriorly  to  the  sensory  tract  are 
not  so  deflected. 

Now,  because  motor  fibers  carry  centrifugal  impulses,  it  is 
logical  to  describe  the  motor  bundles  of  the  internal  capsule 
from  above  downward,  beginning  with  an  enumeration  of 
the  convolutions  from  which  the  motor  fibers  are  believed  to 
spring,  and  tracing  the  course  of  these  fibers  to  their  connec- 
tion with  the  cells  of  the  anterior  horns  of  the  spinal  gray 
matter,  while  it  is  customary  to  reverse  the  method,  in  case 
the  sensory  fibers,  which  carry  centripetal  impulses,  are  under 
consideration. 

The  diagram  to  which  I  shall  first  call  your  attention  (Fig. 
14)  was  designed  by  its  author  (Seguin)  to  rudely  represent 
the  general  features  of  the  internal  capsule.  It  is  impossible 
to  properly  portray  all  of  the  more  important  facts,  to  which 
I  shall  call  attention,  by  any  form  of  schematic  drawing ;  so 
that  the  diagram  offered,  which  is  most  excellent  of  its  kind, 

13 


168  ^^^  THE  BRAIN.  ^^^^^^^B 

can  not  more  than  afford  general  hints  of  valne,  and  shonld 
be  used  as  a  guide  only  in  contrast  with  more  elaborate  cuts 
found  in  standard  anatomical  works. 

The  motor  bundles  arise  from  the  cells  of  the  cerebral 
cortex  comprised  within  the  convolutions  of  the  middle  region 
of  the  brain.  This  region — the  so-called  ''motor  district" — 
includes  the  ascending  frontal  gyrus ^  the  basis  of  the  first, 
second^  and  third  frontal  gyri,  the  ascending  parietal  gyrus, 
the  paracentral  lobule,  and  the  supramarginal  gyrus '  (Fig. 
22).  Some  of  these  bundles  pass  directly  into  the  substance 
of  the  caudate  nucleus,  some  into  the  lenticular  nucleus,  and 
possibly  a  few  into  the  optic  thalamus  of  the  corresponding 
hemisphere,  after  traversing  the  medullary  center  of  the  cere- 
brum ;  but  the  majority  appear  to  pass  directly  into  the 
anterior  portion  of  the  thalamo-lenticular  division  of  the  in- 
ternal capsule  (Figs.  38  and  39). 

The  sensory  fibers  which  are  comprised  within  the  in- 
ternal capsule  are  prolonged  upward  from  the  posterior  parts 
of  the  crus  (tegmentum  cruris  cerebri — Fig.  8)  to  the  con- 
volutions of  the  occipital,  temporo- sphenoidal,  and  parietal 
lobes.  It  is  believed  that  the  posterior  third  (or  sensory  por- 
tion) of  the  internal  capsule  has  connections  also,  by  means  of 
the  optic,  olfactory,  gustatory,  and  acoustic  nerves,  with  the 
peripheral  organs  of  special  sense.  Physiological  experiment 
has  shown  that,  when  certain  convolutions  of  the  sensory 
regions  of  the  cerebral  cortex  have  been  destroyed  in  animals, 
the  senses  of  sight,  smell,  hearing,  and  taste  have  been  either 
temporarily  or  permanently  impaired.  We  know  also  that 
total  hemiansesthesia  results  from  lesions,  both  in  man  as  well 
as  animals,  which  involve  the  posterior  third  of  the  inter- 
nal capsule.  The  impairment  of  special  senses  from  cortical 
lesions,  moreover,  appears  to  be  confined  chiefly  to  the  side 
opposite  to  the  seat  of  injury,  in  case  of  unilateral  destruc- 
tion of  the  cerebml  convolutions — phenomena  which  point 
strongly  to  a  decussation  of  these  fibers,  in  which  respect  they 
bear  an  analogy  to  the  common  sensory  tracts.     Future  con- 

*  The  term  "  gyrus  "  is  synonymous  with  "  convolution." 


CONSTRUCTION  OF  INTERNAL    CAPSULE,  159 

sideration  will  be  given  to  these  points.  Some  of  them, 
particularly  bearing  upon  the  location  of  an  olfactory,  optic, 
and  acoustic  center,  within  the  substance  of  the  thalamus, 
have  already  been  discussed  at  some  length  in  previous 
pages. 

When  we  discussed  the  corpus  striatum,  I  constructed  for 
you  a  diagram  which  represented  the  afferent  and  efferent 
fibers  of  that  ganglion,  in  which  the  motor  fibers  of  the  inter- 
nal capsule  were  shown  (Fig.  40).  I  stated  at  that  time  that 
the  functions  of  the  caudate  and  lenticular  nuclei  were  still 
unsettled,  but  that  physiological  and  pathological  facts  could 
be  advanced  to  sustain  the  belief  that  the  cells  of  both  halves 
of  that  ganglion  exercised  a  modifying  and  controlling  influ- 
ence upon  motor  phenomena,  and  were  probably  the  seat  of 
automatic  action,  irrespective  of  the  cells  of  the  cerebral  cor- 
tex. I  stated,  also,  that  it  was  probable  that  the  cerebel- 
lum had  a  direct  connection  with  the  cells  of  the  caudate 
nucleus,  and  that  physiological  experiment  pointed  strongly 
to  cerebellar  innervation  of  motor  acts,  because  disturbances 
in  coordination  of  movement  aTe"  produced  by  disease  of  the 
cerebellum,  and  motor  acts  appear  to  be  weakened.  Now, 
because  experiments  made  upon  the  caudate  and  lenticular 
nuclei  can  hardly  be  said  to  have  afforded  results  which  can 
be  made  the  basis  for  positive  deductions  respecting  the  func- 
tions of  each,  it  seems  highly  probable  that  the  cerebellar 
fibers  are  in  some  way  connected  with  those  of  the  internal 
capsule,  which  are  unquestionably  associated  with  motor  phe- 
nomena. 

Among  the  afferent  fibers  of  the  corpus  striatum,  in  addi- 
tion to  the  cerebellar  fasciculus  (fibers  of  the  processus  cere- 
helli  ad  cerehrum\  maybe  mentioned  the  '^ corona  radiata^^ ; 
the  ''stria  cornea^'';  fibers  from  the  cortex  of  the  olfactory 
lobe;  and  fibers  from  the  septum  lucidum  (Fig.  40).  If  it 
can  be  shown  that  these  five  sets  of  afferent  nerves  become 
associated  with  those  of  the  internal  capsule,  it  will  help  us 
to  better  interpret  the  functions  of  the  parts.  Spitzka  hap- 
pily remarks  that  ''  the  time  has  passed  when  any  single  ex- 


160 


THE  BRAIK 


periment  can  be  advanced  to  prove  the  existence  of  isolated 
functions  within  ganglionic  masses.  Anatomical  research 
has  demonstrated  that  nerve-tracts  frequently  traverse  these 


Efferent  fibers 
corpus  striatum. 


Fig.  40. — A  diagram  designed  to  show  the  afferent  and  efferent  Jibers  of  the  corpm 
striatum  and  those  of  the  internal  capsule. 

C.  N.y  "  caudate  nucleus,"  or  ventricular  portion  of  corpus  striatum ;  L.  iV.,  lenticular 
nucleus,"  or  extra-ventricular  portion  of  corpus  striatum  ;  A-B,  median  line,  separat- 
ing cerebral  hemispheres ;  P-Fy  psycho-motor  regions  of  the  cortex ;  a,  peduncular 
fibers  connected  with  Z.  N.  ;  b,  fibers  of  the  so-called  "  internal  capsule  "  ;  c,  fibers 
connected  with  C.  N.  ;  0,  olfactory  fibers. 

masses  (without  any  apparent  association  with  the  cells  im- 
bedded within  them)  in  order  to  terminate  in  remote  parts. 


CONSTRUCTION  OF  INTERNAL   CAPSULE,  161 

It  has  been  conclusively  proved  also  that  special  centers  are 
sometimes  interspersed  between  these  nerve-bundles,  so  that 
it  is  illogical  to  attribute  every  phenomenon  caused  by  an 
intra-cranial  experiment  to  a  disturbance  in  the  activity  of 
any  special  center." 

The  physiology  of  many  parts  of  the  brain  is  far  from 
satisfactorily  marked  out.  Many  glaring  contradictions  are 
apparently  proved  by  the  experiments  of  different  investiga- 
tors, and  the  statements  previously  made  will  help,  to  some 
extent,  to  explain  them.  I  pointed  out,  when  discussing  the 
structural  anatomy  of  the  thalamus,  that,  until  the  existence 
of  the  special  centers,  which  are  believed  to  exist  by  some 
authorities  within  that  ganglion,  could  be  positively  demon- 
strated, it  will  be  maintained  by  others  that  many  phenomena 
which  accompany  lesions  of  the  thalamus  are  due  entirely  to 
pressure  exerted  upon  the  adjacent  internal  capsule.  This 
view  is  held  also  by  many  neurologists,  when  phenomena 
provoked  by  any  experiment  upon  the  corpus  striatum '  are 
adduced  to  prove  a  special  function  as  located  within  that 
ganglion.  Pathological  research  has,  in  some  instances, 
seemed  to  oppose  the  view  that  the  lenticular  nucleus  pos- 
sesses any  important  motor  functions.  The  French  experi- 
menters, Franck  and  Pitres,  published,  however,  in  1878,  a 
most  brilliant  attempt  to  demonstrate  conclusively  that  cer- 
tain fibers  of  the  internal  capsule  were  continuous  with  the 
motor  convolutions  of  the  cerebrum  and  conducted  motor 
impulses.  These  physiologists ,  found  that  when  the  white 
substance  of  the  cerebral  hemisphere,  which  underlies  the 
motor  convolutions,  was  faradized,  muscular  movements  were 
created  on  the  opposite  side  of  the  body,  in  definite  regions 
corresponding  to  the  supposed  action  of  the  so-called  ^' motor 
centers  "  of  the  cortex.  It  must  be  confessed  by  all  that  these 
observations,  which  are  considered  by  many  as  a  final  proof 

^  It  is  possible  that  the  caudate  nucleus^  when  seriously  impaired  by  lesions,  may  cause 
hemiplegia  and  secondary  degeneration.  Charcot  claims,  however,  that  the  effects  of 
haemorrhage  of  the  corpus  striatum  are  to  be  attributed  entirely  to  pressure  upon  the 
motor  fibers  of  the  internal  capsule. 


162 


THE  BRAIK 


% 


of  the  distribution  and  function  of  this  bundle  of  fibers,  are 
among  the  most  satisfactory  which  have   been  as  yet 
corded. 

Before  we  pass  to  the  consideration  of  the  internal  capsule' 
in  its  practical  aspects,  let  us  speak  a  little  more  definitely  in  I 
regard  to  its  exact  situation  and  limits.  This  bundle,  as  was  ' 
stated  before,  lies  between  the  lenticular  nucleus  on  the  one 
side,  and  the  caudate  nucleus  and  the  optic  thalamus  on  the  i 
other.  Transverse  vertical  sections  of  the  cerebrum  show  that  j 
the  lenticular  nucleus  lies  external  to  and  below  it,  while  the  1 
caudate  nucleus  and  thalamus  lie  internal  to  and  above  it.       yj " 

In  the  region  of  the  base  of  the  cerebrum,  the  head  of  the     j 
caudate  nucleus  becomes  fused  with  the  lenticular  nucleus,      i 
so  that  the  internal  capsule  does  not  extend  to  the  extreme     \ 
anterior  limits  of  these  ganglionic  masses.   The  posterior  limit     | 
of  the  internal  capsule  is  probably  defined  by  the  termina-     i 
tion  of  the  lenticular  nucleus,  the  thalamus  being  prolonged     ! 
beyond  it  into  the  substance  of  the  cerebral   hemisphere. 
Above  the  level  of  the  basal  ganglia  the  fibers  of  this  bundle 
radiate  into  the  different  lobes  of  the  cerebrum,  and  cease  to 
be  "  capsular  fibers,"  properly  speaking. 

To  the  naked  eye  the  fibers  of  the  internal  capsule,  which  \ 
pass  between  the  ganglionic  masses  at  the  base  of  the  hemi- 
sphere, appear  to  be  continuous  with  the  corona  radiata  above, 
and  the  fibers  of  the  crus  cerebri  below.  There  is  a  belief  ; 
among  some  anatomists,  however,  that  successive  loops  will  j 
probably  be  demonstrated  by  more  extended  research — thejc  i  i 
fibers  of  the  crus  leaving  the  internal  capsule  to  join  the  cellfiNr;^ 
of  the  basal  ganglia,  while  others  leave  the  ganglia  to  pass,  by  ! 
means  of  the  internal  capsule,  to  the  cerebral  convolutions,  i 
The  results  lately  obtained  by  Franck  and  Pitres,  from  anf  ■ 
experimental  standpoint  (mentioned  on  a  preceding  page),  as>  \ 
well  as  those  lately  published  by  Flechsig,  from  investigations  I 
made  upon  the  fetal  brain,  seem,  however,  to  be  rather  op- 
posed to  this  view,  although  they  perhaps  do  not  positively  ' 
controvert  it.  This  point  cannot  be  positively  decided  until  ! 
the  functions  of  the  basal  ganglia  are  determined. 


LESIONS  OF  INTERNAL   CAPSULE.  163 

EFFECTS   OF   LESIONS   OF   THE   li^TERNAL   CAPSULE. 

The  situation  of  this  bundle  of  nerve-fibers  renders  it  liable 
to  become  directly  involved  when  haemorrhage,  softening,  or 
tumors  of  the  central  portions  of  the  hemisphere  exist ;  or, 
indirectly,  when  these  conditions  affect  the  caudate  nucleus, 
the  lenticular  nucleus,  or  the  optic  tlialamus. 

The  most  frequent  seat  of  cerebral  apoplexy  is  the  corpus 
striatum  ;  because  that  ganglion  is  extremely  friable  and  very 
vascular.  The  optic  thalamus  probably  ranks  next  in  the 
order  of  comparative  frequency.  The  blood-vessels  which 
enter  these  bodies '  through  the  anterior  and  posterior  perfo- 
rated spaces  at  the  base  of  the  cerebrum  seem  to  be  frequently 
affected  with  atheromatous  degeneration  and  miliary  aneu- 
rysms," and  are  often  ruptured  when  subjected  to  any  unnatu- 
ral strain.  Nature  has  given  to  the  carotid  and  the  vertebral 
arteries  a  remarkable  tortuosity  before  their  entrance  into  the 
cavity  of  the  cranium,  in  order,  as  it  were,  to  diminish  the 
liability  to  rupture  of  blood-vessels  by  decreasing  the  velocity 
of  the  flow  when  the  heart's  action  is  excessive  ;  but  even  this 
mechanical  safeguard  is  not  always  sufficient  to  protect  the 
intracranial  vessels  from  rupture  when  extensively  diseased. 

Again,  the  condition  of  softening  may  result  from  embolic 
obstruction  to  some  branches  of  the  carotid  (usually  of  the 
left  side),'  because  the  nutrition  of  the  parts  supplied  by  the 

'  The  motor  regions  of  the  cortex  are  supplied  by  the  middle  cerebral  artery ;  the 
nucleus  caudatus  by  branches  of  the  anterior  cerebral  and  anterior  communicating  arte- 
ries ;  the  lenticular  nucleus  by  the  middle  corbral ;  and  the  optic  thalamus  by  branches 
of  the  middle  and  posterior  cerebral  vessels. 

2  The  vessels  most  frequently  affected  with  aneurysmal  dilatations  are  the  internal 
carotid,  basilar,  and  middle  cerebral.  Within  the  cavernous  sinus  large  aneurysmal 
tumors  are  not  uncommon.  It  must  not  be  supposed,  however,  that  the  smaller  vessels 
of  the  brain  are  exempt.  Miliary  aneurysms,  which  give  to  an  artery  and  its  branches 
an  appearance  resembling  a  bunch  of  grapes,  frequently  affect  the  vessels  that  form  the 
circle  of  Willis,  and  even  those  of  the  pia  mater  within  the  substance  of  the  brain  and  in 
the  ventricles.  The  small  vessels  which  nourish  the  corpora  striata  and  the  optic  thalami 
are  sometimes  affected. 

Miliary  aneurysms  frequently  coexist  with  aneurysmal  tumors  outside  of  the  cranium, 
but  they  seem  to  exhibit  an  independence  of  atheroma  which  is  quite  remarkable. 

3  The  reasons  for  this  fact  can  be  found  mentioned  in  a  late  work  by  the  author— 
"  Practical  Medical  Anatomy."     William  Wood  &  Co.,  1882. 


164 


THE  BRAIK 


occluded  vessel  is  thus  arrested  either  entirely  or  in  part. 
The  same  result  may  also  follow  an  attack  of  cerebritis  or  a  g 
previous  extravasation  of  blood  into  the   substance  of  the 
brain,  both  of  which  tend  often  to  create  impairment  of  the 
blood-supply  to  adjacent  regions.  ^ 


Fig.  41. — Miliary  aneurysms  of  a  cerebral  artery.     (After  Hammond.) 


Finally,  tumors  sometimes  develop  within  the  cerebral 
hemispheres,  and  create  pressure  upon,  as  well  as  destruction 
of,  important  nerve- tracts.  Time  will  not  permit  us  to  enter 
into  detail  respecting  all  the  diagnostic  points  by  which  the 
existence  of  each  of  these  conditions  may  be  recognized  during 
life.  I  direct  your  attention,  therefore,  only  to  such  points  as 
are  of  importance  in  the  diagnosis  of  disturbance  of  the  sup- 
posed functions  of  the  internal  capsule. 

It  may  be  stated  with  some  degree  of  positiveness  that,  if 
the  anterior  part  of  the  "  thalamo-lenticular  "  division  of  the 
internal  capsule  (Fig.  38)  be  affected,  a  hemiplegia  of  the 
opposite  side  is  developed.'  This  is  more  or  less  complete, 
according  to  the  seat  and  extent  of  the  lesion  which  causes  it. 
The  exciting  cause  may  possibly  be  situated  within  the  ante- 
rior or  middle  portions  of  the  white  center  of  the  cerebral 

*  Exceptions  to  this  rule  are  occasionally  observed.  The  hemiplegia,  in  rare  cases, 
exists  on  the  same  side  as  the  lesion.  The  explanation  of  this  fact  has  been  shown,  by 
the  researches  of  Flechsip;,  to  lie  in  the  varyinp;  proportions  of  the  direct  and  decussating 
fibers  which  pass  from  the  cerebrum  to  the  spinal  cord. 


LESIONS  OF  INTERNAL   CAPSULE.  165 

hemisphere,  above  the  level  of  the  basal  ganglia,  in  which  case 
it  will  interfere  with  the  normal  action  of  certain  bundles  of 
the  internal  capsule  which  spring  from  the  motor  convolu- 
tions of  the  cortex  previously  enumerated.  Again,  it  may  be 
situated  within  the  constricted  portion  (the  capsule  proper), 
in  which  case  bundles  of  'nerve-fibers,  functionally  associated 
with  widely  diffused  areas  of  the  cortex,  may  be  affected  by 
a  lesion  of  small  size.  Finally,  it  may  be  apparently  confined 
to  the  substance  of  one  of  the  two  nuclei  of  the  corpus  stri- 
atum (Fig.  40),  or  the  optic  thalamus,  and  still  exert  sufficient 
pressure  upon  the  constricted  part  of  the  internal  capsule 
to  produce  more  or  less  extensive  and  complete  paralysis — 
chiefiy  of  the  opposite  lateral  half  of  the  body.  The  hemi- 
plegia of  intra-cerebral  lesions  forms,  as  a  rule,  a  striking 
contrast  with  the  various  types  of  monoplegia  (p.  85),  which 
are  produced  by  circumscribed  lesions  of  the  cortex.  The 
latter  are  often  of  the  greatest  aid  to  the  neurologist  in  local- 
izing the  seat  of  the  exciting  cause.'  They  have  been  dis- 
cussed in  preceding  pages. 

The  second  symptom  which  may  indicate  a  lesion  of  the 
internal  capsule  is  hemi-ancesthesia.  By  this,  I  mean  a  loss 
of  sensation,  more  or  less  complete,  which  is  confined  to  the 
lateral  half  of  the  body.  It  exists  (save  in  rare  instances) 
on  the  side  opposite  to  the  seat  of  the  lesion. 

This  may  occur  when  fibers  of  the  sensory  tract  of  the 
internal  capsule  (Fig.  39)  are  destroyed  or  impaired  by  dis- 
eased conditions  directly  affecting  them,  as  noted  by  Charcot, 
Raymond,  Eendu,  Ferrier,  and  others,  or  by  the  pressure 
exerted  by  lesions  situated^  in  parts  adjacent  to  them.  It  is 
usually  accompanied  with  a  slight  form  of  motor  paralysis  ; 
probably  because  a  few  of  the  motor  fibers  of  the  internal 
capsule  are,  as  a  rule,  simultaneously  interfered  with.  The 
tests  by  which  this  condition  may  be  recognized  are,  doubt- 
less, familiar  to  you  all.  No  examination  of  a  patient  afflict- 
ed with  paralysis  is  ever  complete  unless  sensation,  as  well 

^  The  term  covers  many  forms  of  paralysis  where  special  groups  of  muscles  are  alone 
affected. 


166  THE  BRAIN. 

as  muscular  power,  is  carefully  tested,  before  a  diagnosis  is 
made. 

A  third  symptom  of  lesions  of  the  internal  capsule  in- 
cludes a  variety  of  manifestations  of  impairment  of  the  spe- 
cial senses. 

In  connection  with  the  discussi6n  of  the  optic  thalamus, 
you  will  recall  the  views  advanced  respecting  the  possibility 
of  existence  of  special  centers  of  smell,  sight,  hearing,  and  sen- 
sation within  the  substance  of  that  ganglion.  Clinical  facts 
point  strongly  also  to  a  relationship  between  nerve  fibers 
related  to  certain  special-sense  perceptions  and  the  internal 
capsule.  We  are  forced  to  admit  that  some  of  the  fibers  of 
the  posterior  part  of  the  internal  capsule  probably  have  a 
direct  or  an  indirect  association  with  smell,  sight,  hearing, 
sensation,  and  perhaps  of  taste  also.  In  a  subsequent  section, 
many  interesting  facts  in  physiology,  which  show  the  value 
of  abnormal  phenomena  in  smell,  sight,  speech,  hearing,  taste, 
etc.,  upon  the  diagnosis  of  intra-cranial  lesions,  will  be  given. 
Many  of  these  might  be  mentioned  here  with  advantage, 
if  space  would  permit.  Charcot  has  endeavored  to  explain 
a  statement,  that  has  until  lately  been  accepted,  viz.,  that 
hemianopsia'  seldom  (?)  occurs  in  connection  with  lesions  of  the 
internal  capsule,  but  an  amblyopia  is  developed  on  the  same 
side  as  the  cutaneous  anaesthesia,  with  a  remarkable  contrac- 
tion of  the  field  of  vision  and  difficulty  in  discrimination  of 
color.  The  explanation  which  this  author  made  of  this  state- 
ment is,  that  a  second  decussation  of  the  fibers  of  the  optic 
nerve  takes  place  somewhere  between  the  optic  chiasm  and 
the  internal  capsule,  probably  in  the  tubercula  quadrigemina. 
Some  late  discoveries  of  Munk  and  Wernicke  (coupled  with  a 
collection  of  autopsies  bearing  upon  the  subject)  have  caused 
this  author  to  modify  his  views.  It  is  now  considered  as 
questionable  if  many  cases,  reported  as  exhibiting  amblyopia 
during  life,  were  not  affected  with  hemianopsia.  This  subject 
will  be  discussed  in  connection  with  the  corpora  quadrigemina. 

*  The  term  "  hemiopia"  signifies  half  sight;  hemianopsia  means  a  blindness  of  one 
half  of  the  retina.     The  latter  is,  therefore,  the  preferable  term  in  this  connection. 


LESIONS   OF  INTERNAL    CAPSULE.  167 

Wlien  the  radiating  fibers  of  the  internal  capsule  are  in- 
volved in  a  lesion  which  creates  a  gradually  increasing  press- 
ure (as  in  the  case  of  tumors  which  grow  slowly)  the  fundus 
of  the  eye  exhibits  morbid  changes  in  the  region  of  entrance 
of  the  optic  nerve  which  are  of  value  in  diagnosis.  The  con- 
dition so  produced  is  commonly  known  as  the  "  choked  dislc.'''' 
It  is  nearly  always  bilateral,  but  often  most  marked  in  one 
eye.  It  may  be  considered  as  one  of  the  most  positive  signs 
of  an  extensive  intra-cerebral  lesion,  and  especially  of  tumors 
of  the  brain. 

When  such  an  eye  is  examined  with  an  ophthalmoscope, 
the  condition  found  is  characterized  by  a  swollen  appearance 
of  the  optic  nerves,  which  project  appreciably  above  the  level 
of  the  surrounding  retina  ;  the  margin  of  the  disk  is  either 
obscured  or  entirely  lost ;  the  arteries  appear  small,  and  the 
veins  large  and  tortuous ;  finally,  small  hemorrhagic  spots 
may  often  be  detected  in  the  retina  near  the  margins  of  the 
disk. 

In  spite  of  this  condition,  the  power  of  vision  may  be  little 
impaired;  so  that  the  existence  of  "choked  disk"  may  be 
unsuspected  unless  the  ophthalmoscope  be  used  before  the 
diagnosis  is  considered  final. 

After  a  number  of  weeks,  and  very  much  longer  if  a  tumor 
is  the  exciting  cause  of  the  condition,  the  appearance  of  the 
disk  changes.  An  unnatural  bluish-white  color,  which  de- 
notes atrophic  changes,  develops ;  the  outline  of  the  disk 
becomes  sharply  defined  ;  the  retinal  vessels  become  smaU ; 
and  vision  becomes  markedly  interfered  with. 

In  exceptional  cases  of  destruction  of  the  internal  capsule, 
the  sense  of  smell  has  been  abolished  on  the  side  opposite  to 
the  seat  of  the  lesion.  This  fact  requires  special  considera- 
tion, as  it  has  been  shown  that  the  center  proper  for  olfactory 
perceptions  seems  to  be  in  the  hemisphere  of  the  same  side. 
Meynert  and  Gudden  claim,  however,  to  have  demonstrated 
the  existence  of  an  olfactory  chiasm  in  the  region  of  the  an- 
terior commissure,  in  animals  where  the  bulbs  are  largely 
developed ;  and  fibers  have  been  traced  in  the  region  of  the 


168  THE  BRAIK 

'-''  svJbiculum  cornu  Ammonis^^''  or  the  tip  of  the  temporo- 
sphenoidal  lobe,  which  connect  the  olfactory  centers  with 
each  other.  The  experiments  of  Ferrier  tend  to  disprove 
the  decussation  of  the  olfactory  paths  in  the  anterior  com- 
missure ;  so  that  the  question  still  remains  unsettled.  The 
sense  of  smell  is  more  commonly  affected  in  the  nostril  of 
the  side  which  corresponds  to  the  seat  of  the  lesion. ' 

Among  the  fibers  of  the  internal  capsule  which  are  dis- 
tributed to  the  temporo-sphemoidal  lobe  some  appear  to  have 
some  association  with  the  sense  of  hearing  ;  but  experimenta- 
tion upon  animals  to  determine  the  exact  seat  of  the  centers 
of  hearing  and  the  effects  of  their  destruction  are  exceedingly 
difficult,  because  the  evidences  of  impairment  of  this  sense 
are  more  or  less  vague.  Ferrier  thinks,  however,  thaT^  the 
superior  temporal  convolution  is  unquestionably  connected 
with  acoustic  perceptions.  The  area  which  he  maps  out  as 
acoustic  in  function  is  quite  extensive. 

The  region  of  the  hippocampus  and  the  posterior  parietal 
convolutions  seems  to  be  chiefly  connected  with  tactile  sen- 
sibility, because  their  destruction  has  been  found  to  create 
more  or  less  loss  of  that  sense  on  the  opposite  side  of  the 
body. 

As  regard3  taste^  the  results  of  experimentation  upon  the 
monkey  tribe  seem  to  point  to  the  lower  portion  of  the  mid- 
dle temporal  convolution  as  the  probable  seat  of  the  centers 
which  are  related  to  that  sense.  **  When  this  region  is  sub- 
jected to  irritation,  certain  reflex  movements  of  the  lips, 
cheek,  and  tongue  are  observed,  which  seem  to  point  to  an 
excitation  of  the  gustatory  sense.  Its  destruction  appar- 
ently causes  an  abolition  of  taste. 

We  have  now  considered  three  of  the  more  prominent 
symptoms  which  are  produced  by  lesions  of  the  internal 
capsule,  and  I  pass  to  a  fourth,  which  I  believe  to  be  of  great 

'  Ferrier  reports  a  case  where  smell  and  taste  were  simultaneously  abolished  by  a 
blow  upon  the  top  of  the  head.     Ogle  records  a  similar  instance. 

*  This  may  help  to  explain  the  fact  that  injuries  received  upon  the  vertex  and  occipital 
protuberance  cause,  in  some  instances,  an  abolition  of  taste,  the  temporal  lobe  being 
injured  by  concussion  against  the  adjacent  bone. 


CONJUGATE  DEVIATION  OF  EYES  AND  HEAD.         169 

value  in  aiding  the  recognition  during  life  of  an  extensive  and 
rapidly  developing  lesion  of  the  white  center  of  the  cerebral 
hemisphere,  viz.,  conjugate  deviation  of  the  eyes  and  head. 

When,  in  connection  with  rapid  softening  or  an  extravasa- 
tion of  blood  into  the  substance  of  the  cerebrum  above  the 
level  of  the  basal  ganglia,  this  peculiar  symptom  is  developed 
(either  simultaneously  with  or  following  paralysis  and  coma), 
the  patient's  head  and  eyes  will  be  observed  to  be  turned  con- 
stantly away  from  the  paralyzed  side  and  toward  the  side 
which  is  the  seat  of  the  lesion.  Various  attempts  have  been 
made  by  late  authors  to  throw  discredit  upon  the  clinical 
significance  of  this  symptom  as  particularly  indicative  of  a 
lesion  of  the  cerebral  hemisphere,  but  I  am  convinced  that  it 
is  a  valuable  differential  sign.  Ferrier  has  demonstrated  that 
a  cortical  center,  which  he  locates  in  the  first  and  second 
frontal  gyri  near  to  their  bases,  presides  over  conjugate  move- 
ments of  the  head  and  eyes,  and  causes  dilatation  of  the 
pupils.  He  attributes  this  symptom,  when  occurring  in  con- 
nection with  hemiplegia  of  cortical  or  ganglionic  origin,  to 
the  unantagonized  action  of  tlie  corresponding  center  of  the 
uninjured  hemisphere,  thus  explaining  the  fact  that  the  dis- 
tortion is  toward  the  side  of  the  lesion.  Clinical  evidence  of 
the  correctness  of  this  view  has  been  brought  forward  by 
Hughlings-Jackson,  Priestley  Smith,  Chouppe,  Landouzy, 
Carroll,  and  others ;  and,  in  some  cases  reported,  the  situa- 
tion of  the  lesion  has  been  verified  by  pathological  observa- 
tion. The  opportunity  to  record  pathological  observations 
upon  cases  where  this  symptom  was  well  marked  during  life 
has,  unfortunately  for  science,  been  a  comparatively  rare  one. 
It  is  impossible,  therefore,  to  speak  positively  concerning  the 
diagnostic  value  of  this  symptom,  although  the  weight  of 
clinical  evidence  seems  to  be  strongly  in  its  favor. 

A  fifth  symptom,  which  points  strongly  to  an  existing 
lesion  of  the  internal  capsule,  is  choreiform  movements  fol- 
lowing hemiplegia  or  hemiansesthesia.  These  movements 
vary  in  type  and  degree.  In  some  cases,  the  movements  ex- 
hibit the  peculiarities  of  athetosis,  the  fingers  or  toes  being 


170  TEE  BRAIN. 

thrown  into  active  motions  whicli  cannot  be  controlled  by 
the  patient ;  in  others,  true  ataxia  may  be  developed  ;  again, 
the  spasmodic  movements  partake  of  the  character  of  gen- 
nine  chorea ;  finally,  a  tremor,  more  or  less  marked,  may  be 
detected. 

It  is  not  uncommon  to  find  that  both  hemiplegia  and 
hemiansesthesia  may  co-exist  with  these  post-paralytic  forms 
of  spasmodic  disease  ;  but  one  usually  overshadows  the  other, 
the  hemiplegia  being,  as  a  rule,  the  more  marked.  How  we 
are  to  explain  these  late  phenomena,  is  not  definitely  settled. 
They  are  probably  to  be  classed  with  other  morbid  manifesta- 
tions which  paralyzed  muscles  sometimes  exhibit,  chiefly  that 
of  ''late  rigidity"  so  often  seen,  concerning  the  cause  of 
which  many  conjectures  have  been  advanced,  but  nothing  of 
a  positive  nature  demonstrated. 

Finally,  it  has  been  observed  that  lesions  of  the  internal 
capsule,  if  very  extensive,  are  often  followed  by  a  very 
marked  rise  in  the  temperature  of  the  body.  We  have  yet 
much  to  learn  concerning  the  vaso-motor  centers  which  are 
variously  disposed  within  the  substance  of  the  brain  and 
spinal  cord. 

The  fact  has  been  mentioned  that  certain  fibers  of  the 
internal  capsule  are  anatomically  related  to  the  cells  in  the 
motor  convolutions  of  the  cerebral  cortex.  Although  there  are 
still  some  neurologists  of  note  who  deny  the  value  of  the  late 
attempts  of  Fritsch,  Hitzig,  Broca,  Ferrier,  Charcot,  Hugh- 
lings-Jackson,  Pitres,  Landouzy,  Exner,  Chouppe,  Luciani, 
Wernicke,  and  a  host  of  others,  to  locate  special  centers 
within  the  convolutions  of  the  cortex,  clinical  and  patho- 
logical observations  are  constantly  being  brought  forward  in 
support  of  the  more  generally  accepted  views.  The  region 
which  embraces  these  motor  centers  appears,  however,  to  be 
somewhat  limited.  A  critical  review  of  recorded  cases  shows, 
I  think,  beyond  cavil,  that  the  white  center  of  each  hemi- 
sphere of  the  cerebrum,  as  well  as  the  cortex,  may  in  some 
instances  be  extensively  diseased  or  injured  without  any 
motor  or  sensory  results  which  can  be  determined.     Patho 


^ 


LESIONS  OF  INTERNAL   CAPSULE.  171 

logical  evidence  seems  to  demonstrate,  however,  tliat  the  re- 
gion so  impaired  must  not  be  situated  where  the  fibers  of 
the  internal  capsule  which  pass  posteriorly  to  its  knee  (Fig. 
39)  can  suffer  destruction  or  pressure  if  we  expect  to  meet 
with  negative  results.  Abscesses  of  immense  size  have  been 
found  in  the  anterior  part  of  the  frontal  lobe  without  any- 
sensory  or  motor  paralysis  during  life  to  indicate  the  exist- 
ence of  such  a  lesion.  Tumors,  softenings,  and  the  most 
severe  types  of  traumatism  have  likewise  occurred  without 
creating  serious  effects. 

In  the  case  of  occipital  and  temporo-sphenoidal  lobes, 
to  which  some  of  the  posterior  fibers  of  the  internal  capsule 
are  probably  distributed,  sensory  symptoms  are  commonly 
observed  to  follow  circumscribed  lesions. 

The  temporal  lobes  seem  to  exert  an  influence  upon  the 
special  senses  of  touch,  smell,  and  hearing.  The  occipital 
convolutions  are  probably  associated  with  vision. 

An  apparent  connection  of  the  optic  and  auditory  func- 
tions with  the  cerebellum  and  optic  thalamus  has  been  men- 
tioned in  previous  lectures.  The  bearing  of  morbid  phenom- 
ena of  these  special  senses  upon  diagnosis  will  be  considered 
in  detail  in  a  subsequent  section  of  this  work. 

In  closing  this .  important  subject,  let  me  suggest  that  it  is 
by  no  means  certain  that  lesions,  which  primarily  affect  the 
constricted  portion  of  the  internal  capsule,  may  not,  in  them- 
selves, create  sufficient  pressure  upon  the  corpus  striatum  and 
the  optic  thalamus  to  cause  interference  with  the  free  action 
of  some  of  the  special  centers  which  are  believed  to  exist 
within  those  bodies.  If  this  be  the  case,  many  of  the  inter- 
esting phenomena  described  during  our  discussion  of  lesions 
of  the  optic  thalamus,  would  co-exist  with  those  symptoms 
of  disease  within  the  internal  capsule  already  mentioned. 
Ritti's  views  respecting  the  relations  of  the  optic  thalamus  to 
hallucinations,  and  those  of  Luys  pertaining  to  its  olfactory, 
optic,  and  acoustic  functions,  have  a  special  interest  in  this 
connection. 


172 


THE  BRAIN. 


THE    CORPORA    QUADRIGEMINA, 


WITH    REMARKS    CONCERNING    THE    DIAGNOSIS    AND    LOCALIZATION       ; 
OF   LESIONS   AFFECTING  SIGHT.'  _■ 

The  aqueduct  of  Sylvius  {iter  e  tertio  ad  quartum  ven-  ^ 
triculitm)  is  covered  on  its  superior  and  dorsal  aspect  by  two  j 
pairs  of  rounded  eminences  (Fig.  38),  mainly  composed  of  j 
gray  matter,  called  the  corpora  or  tubercula  quadrigemina  | 
(the  so-called  ^'nates''''  and  ''testes  cerebrV).  A  median  ■ 
groove  separates  these  parts.  Anteriorly,  a  transverse  white  j 
prominence  (the  posterior  commissure)  limits  this  groove  j 
(Fig.  37) ;  behind,  it  is  continuous  with  the  velum  by  means  j 
of  a  small  median  strand  of  longitudinal  fibers,  called  the  ! 
frenulum  veli.  The  pineal  gland  which  projects  backward  \ 
and  downward  from  the  posterior  wall  of  the  third  ventricle  ^ 
overlaps  the  anterior  portion  of  this  groove,  resting  between  i 
the  two  upper  quadrigeminal  bodies  (the  nates).  In  fishes, 
reptiles,  and  birds,  the  quadrigeminal  bodies  are  two  in  num-  i 
ber,  and  are  called  the  optic  lobes.  They  are  also  hollow  in  1 
these  species.  In  the  human  fcetus  they  are  developed  early,  i 
and  form  a  large  part  of  the  cerebral  mass.  «**i 

The  anterior  tubercles  are  darker  in  color  and  less  promi-  \ 
nent  than  the  posterior.  Laterally,  each  tubercle  is  prolonged  j 
upward  and  forward  into  a  prominent  strand  of  white  su 
stance,  the  brachium  or  arm  of  the  corresponding  tubercle. 

The  hracliia  are  to  be  regarded  as  fasciculi  sent  to  each, 
tubercle  from  the  cortex  cerebri  by  means  of  the  corona 
radiata.  They  may  also  be  considered  as  affording  a  com- 
munication with  the  optic  thalamus.  The  upper  or  anterior 
brachium  passes  between  the  inner  geniculate  body  and  the 
posterior  extremity  of  the  optic  thalamus,  or  the  pulmnar^ 
where  it  may  be  demonstrated  to  join  one  of  the  roots  of  the 
optic  tract,  of  which  it  really  is  a  continuation.  This  is  more 
apparent  in  some  animals  than  in  man.     The  loicer  or  pos- 

'  In  connection  with  the  description  of  the  ganglia  of  the  "  tegnicntuni  cruris,"  theSlfc-i 
bodies  are  considered  from  the  standpoint  of  their  other  physiological  functions.  ^^ 


THE  CORPORA    QUADRIGEMmA,  I73 

terior  hracMum  loses  itself  underneatli  the  inner  geniculate 
body,  which  is  situated  at  the  side  of  the  upper  end  of  the 
cms  cerebri. 

The  superior  quadrigeminal  bodies^  or  nates  cerebri,  are 
covered  externally  with  a  thin  layer  of  nerve  fibers,  called  the 
'' stratum  zonaUy  This  constitutes  the  only  place  in  the 
brain  where  fibers  of  the  first  projection  system  of  Meynert 
(p.  31)  are  exposed  to  view  upon  its  exterior.  Beneath  this 
may  be  seen  a  layer  of  gray  matter,  called  the  "stratum  cine- 
reum,,^^  which  is  thicker  at  the  prominent  part  of  the  tuber- 
cle than  at  its  margins,  and  which  contains  numerous  nerve 
cells  of  small  size.  Beneath  this,  again,  lies  a  layer  of  nerve 
fibers  which  are  arranged  in  longitudinal  bundles,  the  so- 
called  "stratum  opticum.^^  These  fibers  are  continuous  with 
the  upper  brachium  and  the  optic  tract.  Scattered  nerve 
cells  are  found  between  the  bundles  of  which  it  is  composed. 
Finally,  between  the  stratum  opticum  and  the  gray  matter 
which  surrounds  the  aqueduct  of  Sylvius,  a  layer  of  nerve 
fibers,  derived  from  the  upper  fillet  or  stratum  lemnisci,  may 
be  demonstrated.  This  layer  is  thickest  at  the  margins  of 
the  tubercle  and  thinnest  at  the  median  line,  where  its  fibers 
appear  to  decussate.  This  gradual  thinning  is  to  be  explained 
by  the  passage  of  some  of  its  fibers  to  the  optic  layer,  and 
some  to  the  gray  matter  surrounding  the  aqueduct  of  Sylvius 
(Tartuferi)/ 

The  inferior  quadrigeminal  bodies,  or  the  testes  cerebri, 
are  composed  almost  entirely  of  gray  matter  formed  of  numer- 
ous small  and  some  large  nerve  cells.  A  thin  layer  of  the  fillet 
separates  the  gray  nucleus  of  this  body  from  the  gray  matter 
surrounding  the  aqueduct  of  Sylvius.     A  connecting  band  of 

'  Flechsig  has  shown  (in  some  late  researches  made  by  him  in  reference  to  the  period 
of  development  of  the  more  important  nerve  tracts  of  the  brain)  that  the  cortical  layer 
of  the  anterior  corpus  quadrigeminum  is  more  intimately  connected  with  the  optic  nerve 
fibers  than  is  the  white  matter  of  that  body.  This  observer  discards  the  internal  genicu- 
late bodies  and  the  posterior  corpora  quadrigemina  from  tjie  optic  apparatus — a  view  that 
is  apparently  supported  by  Guddcn's  method  of  research.  In  the  section  of  this  work 
devoted  to  the  special  consideration  of  the  cranial  nerves,  the  optic  fibers  will  be  further 
discussed,  and  some  of  the  later  discoveries  of  Gudden  and  Ganser  will  then  be  men- 
tioned. 

14 


174  ^^^"^  THE  BRAIK  ^^^^^^^M 

gray  matter  unites  the  gray  nuclei  of  the  two  bodies.  Trans- 
verse fibers  of  the  fillet  bound  this  gray  commissural  band 
both  superficially  and  deeply.  Those  lying  superficially  are 
continuous,  in  part,  with  the  brachium  of  the  lower  quadri- 
geminal  body,  and  in  part,  also,  with  the  fibers  of  the  lower 
fillet ;  the  fibers  of  the  lower  fillet  are  described  by  Meynert 
as  being  continuous  with  the  brachium  of  the  opposite  side. 
If  this  continuity  really  exists,  the  communication  is  probably 
an  indirect  one  by  means  of  interposed  nerve  cells  in  the  gray 
matter. 

The  posterior  commissure  of  the  third  ventricle,  which 
lies  above  the  upper  end  of  the  aqueduct  of  Sylvius,  seems  to 
be  a  direct  continuation  of  the  commissural  fibers  of  the  fillet 
which  have  been  mentioned.  It  apparently  springs  from  the 
tegmentum,  and,  after  decussating,  appears  to  traverse  the 
substance  of  the  thalamus,  and  then  to  radiate  in  the  white 
substance  of  the  hemisphere  of  the  cerebrum.  A  few  of  its 
fibers  are  connected  with  the  pineal  gland ;  some  also  prob- 
ably act  as  commissural  fibers  between  the  thalami  (Fig.  37). 

This  hasty  and  somewhat  imperfect  resume  of  the  anato- 
my of  these  bodies  will  enable  us  to  intelligently  consider 
some  of  the  views  which  have  been  advanced  respecting  their 
probable  functions,  and  the  effects  of  lesions  within  their 
substance. 

Functions  of  the  Corpora  Quadrigemina. — Among  the  in* 
vestigators  who  have  devoted  special  attention  to  these  bodies, 
Adamuck,  Knoll,  Budge,  Hensen,  Voelkers,  Flourens,  Schiff, 
Ferrier,  McKendrick,  Gudden,  and  many  others  of  note,  may 
be  prominently  mentioned.  Some  have  observed  the  effects 
of  their  removal  in  animals  ;  others  have  studied  the  resulta 
of  stimulation  of  their  superficial  and  deep  parts  ;  while  a  few 
have  recorded  the  results  of  destruction  of  the  optic  apparatus 
and  certain  convolutions  of  the  cerebral  hemispheres,  as  pos- 
sessing a  peculiar  bearing  upon  points  in  dispute  regarding 
these  bodies.  From  these  different  sources  a  mass  of  evidence 
has  been  accumulated  which  appears  in  some  instances  to 
lead  to  contradictory  conclusions.     It  is  only  by  comparing 


FUNCTIONS  OF  CORPORA    QUADRIGEMINA.  175 

the  views  of  the  investigators  mentioned,  and  bringing  to  bear 
upon  the  subject  what  is  also  taught  us  by  anatomical  re- 
search, that  the  web  may  be  partially  disentangled.  This 
subject  will  be  considered  again  in  connection  with  the  fibers 
of  the  tegmentum  cruris  which  are  associated  with  these 
bodies. 

The  connection  of  the  anterior  quadrigeminal  bodies,  or 
the  nates  cerebri^  with  the  optic  tract  and  the  sense  of  sight 
appears  to  be  far  more  intimate  than  that  of  the  posterior 
lobules,  or  testes  cerebri^  as  was  first  pointed  out  clearly  by 
Gudden.  This  observer  found  that  the  extirpation  of  the  eye 
on  one  side  of  a  young  animal  was  followed  by  a  degenera- 
tion and  atrophy  of  the  natis  cerebri  and  its  brachium ;  the 
testis  and  its  brachium  remaining  unaltered.  This  view  is 
apparently  sustained  also  by  the  fact  that  the  mole  has  the 
testes  cerebri  largely  developed,  whereas  the  nates  cerebri  are 
markedly  atrophied.  Adamuck  believed  that  he  had  clearly 
demonstrated  the  existence  of  a  center  within  the  nates  which 
presided  over  those  movements  of  the  eye  and  pupil  which 
are  essential  to  the  accominodation  of  vision  for  near  ob- 
jects^ as  well  as  the  coordination  of  all  ocular  movements. 
Knoll  found,  however,  that  reflex  contractions  of  the  pupil 
remained  after  removal  of  the  corpora  quadrigemina ;  and 
Hensen  and  Voelkers  have  been  apparently  successful  in 
mapping  out  the  topography  of  the  centers  which  preside 
over  ocular  and  pupillary  movements  with  greater  accuracy 
than  their  predecessors.  They  were  able  to  produce  at  will,  by 
carefully  applied  electric  stimulation  in  the  region  of  the  floor 
of  the  aqueduct  of  Sylvius,  independent  movements  of  the 
eye  and  pupil.  In  the  dog,  upon  which  animal  these  experi- 
ments were  made,  a  center  which  governed  the  accommoda- 
tion of  vision '  was  found  to  be  situated  in  the  posterior  part 
of  the  third  ventricle  near  to  the  aqueduct,  while  a  center  for 
pupillary  contraction  and  one  also  for  its  dilatation  were  found 
in  the  front  part  of  the  floor  of  the  aqueduct  of  Sylvius,  the 

^  This  center  manifested  an  apparent  control  over  the  ciliary  muscle  only,  and  created 
alterations  in  the  anteroposterior  measurement  of  the  crystalline  lens  of  the  eye. 


176  THE  BRAIK 

former  lying  in  the  median  plane  and  the  latter  more  to  the 
sides.  The  same  observers  state  that  a  center,  which  governs 
those  muscles  of  the  eyeball  which  are  supplied  by  the  third 
cranial  nerve,  can  be  found  in  the  floor  of  the  aqueduct,  im- 
mediately behind  that  which  presides  over  pupillary  contrac- 
tion. Whether  we  accept  these  statements  as  demonstrated 
or  not,  we  know  positively  that  such  centers  exist  somewhere, 
and  are  so  associated  in  their  action  that,  when  the  eyeballs 
are  directed  inward  and  downward,  as  for  near  vision,  the 
pupils  are  at  the  same  time  contracted  ;  and  when  the  eye- 
balls are  directed  upward  and  returned  to  a  state  of  paral- 
lelism, the  pupils  are  dilated  to  a  corresponding  extent.  On 
the  contrary,  when  the  eyeballs  are  moved  sideways  in 
unison,  the  pupils  remain  unchanged.  A  most  positive  proof 
that  the  pupillary  movements  are  not  of  a  psychical  nature  is 
afforded  by  the  experiments  of  Adamuck,  who  produced 
movements  of  both  eyes  by  stimulation  of  the  corpora  quadri- 
gemina  of  either  side,  and  who  also  observed  that  the  pupils 
were  at  the  same  time  made  to  perform  their  proper  move- 
ments. When,  however,  the  corpora  quadrigemina  of  the 
two  sides  were  separated  by  a  median  incision,  stimulation  of 
the  centers  of  either  side  caused  movements  of  the  corre- 
sponding eyeball  only.  In  both  experiments,  changing  the 
seat  of  stimulation  caused  modifications  of  ocular  move- 
ments. 

It  was  only  after  Knoll  had  shown  that  the  reflex  move- 
ments of  the  pupils  remained  after  complete  excision  of 
the  corpora  quadrigemina,  and  the  discovery  of  Hensen  and 
Voelkers  that  the  effects  of  stimulation  of  these  bodies,  as 
first  practiced  by  Adamuck,  were  not  uniform  until  the  un* 
derlying  parts  were  directly  reached,  that  discrepancies  be- 
tween these  observers  were  explained. 

To  determine  the  true  relations  which  these  bodies  bear  to 
the  special  sense  of  sight  is  perhaps  one  of  the  most  difficult 
problems  in  physiology. 

Flourens  and  many  subsequent  observers  have  shown  us 
that  unilateral  extirpation  of  the  corpora  quadrigemina  in 


FUNCTIONS  OF  CORPORA    QUADRIGEMINA.  177 

mammals  and  birds  leads  to  a  blindness  of  the  opposite  eye  : 
and  even  when  the  cerebral  hemispheres  are  removed  without 
disturbing  these  bodies,  that  an  apparently  crude  vision  still 
remains.  We  have  many  experiments,  however,  to  show  that 
destruction  of  certain  convolutions  of  the  cerebrum  also  pro- 
duced the  most  profound  effects  upon  vision  in  spite  of  the 
undisturbed  action  of  the  quadrigeminal  bodies.  When  we 
discussed  the  optic  thalamus,  it  was  also  stated  that  many 
clinical  observations  pointed  toward  the  existence  of  a  center 
within  that  body  which  in  some  way  modified  or  presided 
over  visual  impressions.  We  know  also  that  lesions  within 
the  so-called  "internal  capsule"  of  the  cerebrum  frequently 
produced  most  serious  impairment  of  vision,  and  conjugate 
deviation  of  the  eyes. 

In  the  pages  which  treat  of  the  ganglia  of  the  tegmentum, 
other  functions  of  the  corpora  quadrigemina  will  be  dis- 
cussed. The  reader  is  referred,  therefore,  to  them  for  more 
exhaustive  information. 

Now,  how  are  we  to  explain,  theoretically,  such  contra- 
dictory phenomena  ?  What  views  are  we  apparently  justified 
in  holding  (from  the  standpoint  of  our  present  knowledge 
upon  the  subject)  regarding  the  relations  of  the  cerebral 
cortex,  corpora  quadrigemina,  corpora  geniculata,  optic 
thalami,  and  internal  capsule  of  the  cerebrum,  to  the  fibers  of 
the  optic  tracts  and  the  external  organs  of  sight  ? 

I  think  we  are  justified  in  attributing  to  the  cells  of  the 
cerebral  cortex  (the  external  gray  matter  of  the  hemispheres) 
our  conceptions  of  the  external  world,  as  portrayed  to  us  by 
means  of  the  sensory  nerves  and  the  special  senses.  No  mat- 
ter how  many  collections  of  gray  matter  may  be  interposed 
along  the  course  of  the  nerve  fibers  which  convey  these  im- 
pressions to  the  cortex  (each  of  which  may  possibly  help  to 
modify  them),  there  is  no  argument  which  has  yet  been  ad- 
vanced which  tends  to  overthrow  this  general  law.  Every 
image  cast  upon  the  retina,  every  sound-wave  which  enters 
the  external  ear,  every  odoriferous  particle  which  reaches  the 
nose  or  is  placed  upon  the  tongue,  every  manner  of  form  by 


178 


THE  BRAIK 


which  we  are  brought  into  direct  or  indirect  relation  with 
surrounding  objects  during  life,  becomes  a  conscious  impres- 
sion only  by  affecting  in  some  unknown  way  the  cells  of  the 
cerebral  cortex.  Here  the  image  thrown  upon  the  retina  be- 
comes to  our  mind  the  picture  actually  seen  ;  the  sound-wave 
becomes  the  musical  note;  the  contact  of  the  odoriferous 
particle  is  transformed  by  the  brain  cells  found  in  its  external 
gray  matter  into  a  sense  of  smell  or  of  taste  ;  objects  become 
recognized  as  smooth  or  rough,  hard  or  soft,  heavy  or  light, 
only  when  these  silent  workers  become  thrown  into  activity 
by  some  sensory  impulse  carried  to  the  convolutions  of  the 
brain  by  means  of  nerve  fibers. 

We  have  reason  to  believe  that  the  fibers  of  the  optic 
nerve  reach  the  gray  matter  of  the  convolutions  of  the  cere- 
brum by  different  routes  ;  and  that  each  bundle  meets  (some- 
where in  its  course)  an  interrupting  mass  of  gray  matter,  with 
the  cells  of  which  the  nerve  fibers  become  associated,  and 
from  which  cells  they  are  subsequently  prolonged  to  those  of 
the  cortex.  This  is  the  common  method  of  arrangement  of 
all  nerve  fibers,  after  they  enter  the  substance  of  the  brain  or 
spinal  cord,  to  which  the  optic  fibers  are  no  exception.  The 
interrupting  cells  of  the  optic  fibers  are  comprised  chiefly 
within  the  optic  thalami,  the  corpora  geniculata,  and  the 
corpora  quadrigemina.  Stilling  believes  that  a  bundle  of 
fibers  can  be  traced  to  the  corpus  suMJialamicum^  and 
another  to  the  medulla  oblongata.  The  so-called  "basal 
optic  ganglion  of  Meynert"  is  thought  by  some  to  be  also 


connected  with  a  slender  fasciculus  of  the  nerve. 


When  speaking  of  these  interpolated  masses  of  gray  mat- 
ter and  their  controlling  action  upon  all  impulses  sent  to  the 
brain,  Michael  Foster  makes  use  of  the  following  words, 
which  I  quote  on  account  of  their  applicability  to  the  subject 
under  consideration : 

''All  day  long  and  every  day,  multitudinous  afferent  im- 
pulses from  eye,  and  ear,  and  skin,  and  muscle,  and  other 
tissues  and  organs,  are  streaming  into  our  nervous  system 
and  did  each  afferent  impulse  issue  as  its  correlative  efferenf 


i. 


5tem  »i 
Perentti 

J 


FUIsTOTIONS  OF  CORPORA    QUADRIGEMINA,  179 

motor  impulse,  our  life  would  be  a  prolonged  convulsion.  As 
it  is,  by  the  checks  and  counter-checks  of  cerebral  and  spinal 
activities,  all  these  impulses  are  drilled  and  marshaled  and 
kept  in  orderly  array  till  a  movement  is  called  for  ;  and  thus 
we  are  able  to  execute  at  will  the  most  complex  bodily  ma- 
noeuvres, knowing  only  why^  and  unconscious  or  but  dimly 
conscious  how^  we  carry  them  out." 

The  study  of  the  course  of  the  individual  libers  of  the 
optic  nerve  in  the  region  of  the  optic  chiasm  (Fig.  41)  is 
rendered  particularly  difficult  by  the  curved  direction  which 
they  take ;  hence  the  relative  proportion  of  the  longitudinal 
and  decussating  bundles  is  still  a  subject  of  dispute  among 
authorities  upon  that  subject.  Stilling  states  that  inter- 
retinal  fibers,  which  have  no  cerebral  connection,  can  be 
demonstrated,  while  other  authors  deny  it.  Some  assert  that 
all  of  the  fibers,  which  are  prolonged  into  the  optic  tract, 
decussate  in  man,  as  they  are  known  to  do  in  the  lower  verte- 
brates and  some  mammals,  but  pathological  observation  tends 
to  confute  this  view.  Charcot  advanced  the  theory  some 
years  since  that  those  fibers  of  the  optic  nerve  which  do  not 
decussate  at  the  chiasm  are  continued  along  the  optic  tract  of 
the  corresponding  side  and  eventually  decussate  (probably 
within  the  substance  of  the  corpora  quadrigemina)  after 
which  they  are  continued  into  the  internal  capsule  of  the  op- 
posite hemisphere.  He  sustained  this  theory  on  pathological 
grounds. 

The  latest  researches  of  Wernicke  and  Stilling  respecting 
the  anatomy  of  the  brain  have  tended,  however,  to  confirm 
the  original  view  of  Meynert  that  the  optic  fibers  radiate  into 
the  occipital  lobes,  as  well  as  that  of  Munk  also,  who  first 
advanced  the  statement  that  the  area  of  the  brain  function- 
ally associated  with  conscious  visual  impressions  was  confined 
to  the  cortex  of  the  occipital  lobes. 

Wernicke  has  shown  conclusively  that  a  tract  of  fibers 
passes  from  the  pulvinar  of  the  optic  thalamus  to  the  occipital 
lobe  of  the  same  hemisphere,  and  that  this  tract  is  continuous 
with  the  fibers  that   compose   the  optic  tract.      He  demon- 


180  THE  BRATN. 

strates  furthermore  that  this  tract  passes  heneath  the  angular 
gyrus.  Ferrier  and  Dalton  have  both  pronounced  the  visual 
area  of  the  cortex  to  be  confined  exclusively  to  these  angular 
convolutions  of  the  parietal  lobe.  This  discovery  of  Wernicke 
seems  to  be  a  means  of  reconciling  the  views  of  Ferrier  and 
Munk,  that  have  been  directly  opposed  to  each  other ;  since 
it  is  evident  that  a  deep  injury  to  the  angular  gyrus  would 
cause  impairment  of  Wernicke's  tract  (see  Fig.  43). 

A  very  valuable  resume  of  the  latest  discoveries,  respect- 
ing the  visual  area  of  the  cerebral  cortex  in  man,  by  means 
of  pathological  investigation,  has  been  lately  published  by 
M.  Allen  Starr,'  of  this  city.  This  author  brings  forward 
the  results  of  autopsies  made  upon  some  thirty  cases  where 
brain  lesions  had  produced  hemianopsia  during  life.  He 
draws  conclusions  from  these  cases  that  differ  from  those 
that  have  been  accepted  as  proved  until  within  the  past  five 
years.  Some  of  the  more  important  deductions  drawn  from 
this  remarkable  compilation  of  autopsies  are  as  follows  : 

1.  The  supposed  decussation  of  those  optic  fibers,  which 
do  not  cross  at  the  chiasm,  within  the  corpora  quadrigemina 
(as  schematically  represented  by  Charcot  in  his  diagram,  and 
taught  by  him  for  years  past),  is  erroneous,  and  has  lately 
been  discarded  by  its  author. 

2.  The  diagram  of  Grafe  and  Fere  meets  with  the  author's 
approval ;  and  it  has  been  adopted  by  Charcot,  as  more  cor- 
rect than  his  own. 

3.  He  sustains  the  opinion  of  Mauthner  that  "there  is  no 
w^ell- authenticated  case  in  which  a  lesion  of  one  hemisphere 
has  produced  blindness  of  the  opposite  side." 

4.  He  believes  that  many  of  the  cases,  reported  as  those  of 
amblyopia  from  brain  lesions,  are  capable  of  being  shown  to 
be  aflfected  with  hemianopsia. 

6.  That  any  lesion  of  the  brain,  if  it  affects  the  fibers  of 
the  optic  tmct,  the  pulvinar,  Wernicke's  tract,  or  the  cortex 
of  the  occipital  lobe,  will  cause  hemianopsia.  Hemianopsia 
must  therefore  be  regarded  as  a  symptom  of  a  circumscribed 

^  *'  American  Journal  of  the  Medical  Sciences,"  January,  1884. 


HEMIANOPSIA  FROM  BRAIN-LESIONS.  181 

lesion  of  one  hemispliere  rather  than  a  general  symptom  of 
brain  disease  (see  Fig.  43). 

6.  That  the  older  view  that  ''lateral  homonymous  hemi- 
anopsia "  is  always  due  to  a  lesion  affecting  the  optic  tracts 
at  the  base  of  the  brain  is  an  error  and  unworthy  of  per- 
petuation. 

7.  That  the  view  of  Munk,  who  believes  that  each  occipi- 
tal lobe  presides  over  the  vision  of  the  corresponding  half 
of  each  eye  (the  left  lobe  over  the  left  half,  and  the  right 
over  the  right  half  of  each  eye),  is  correct.  The  view  of  Fer- 
rier,  that  the  angular  gyrus  is  directly  associated  with  the 
visual  sense,  is  not  thus  far  supported  by  pathological  re- 
search in  man. 

It  is  known  that  destruction  of  the  retina  in  the  dog  gives 
rise  to  a  degeneration  of  nerve  strands  in  both  optic  tracts. 
The  chiasm  of  the  cat  has  been  divided  without  destroying 
vision,  thus  warranting  the  inference  that  the  decussation  at 
that  point  is  incomplete.  All  the  experiments  that  have  been 
made  to  determine  the  relation  of  the  cortex  cerebri  to  vision 
are  in  favor  of  an  incomplete  decussation,  because  the  sight 
of  both  eyes  has  been  impaired  by  unilateral  lesions.  A 
large  number  of  cases  have  been  reported  where  lesions 
affecting  one  optic  tract  have  produced  hemianopsia  of  both 
retinse. 

Possibly  the  corpora  quadrigemina  preside  over  other 
functions  in  addition  to  the  special  sense  of  sight.'  Flourens 
was  the  first  to  notice  that  injuries  of  the  corpora  quadri- 
gemina, of  one  side  produced  peculiar  phenomena  called 
"•forced  movements ^^''  and  that  the  complete  removal  of 
these  bodies  caused  inco-ordination  of  movement.  These 
experiments  have  been  repeatedly  verified.  In  the  frog, 
the  removal  of  the  optic  lobes  causes  an  almost  entire 
loss  of  the  power  of  co-ordination  of  movements  required  to 
preserve  its  balance;  but  it  can  still  perform  a  variety  of 
movements  where  co-ordination  is  demanded,  such  as  swim- 

'  The  inferior  corpora  qviadrigernina  do  not  appear  to  be  directly  associated  with  optic 
fibers  (Flechsig  and  Gudden). 


182  THE  BR  Am.  fRPi|^^^^H 

ming,  leaping,  etc.  Schiff  has  attributed  these  effects,  how- 
ever, to  injury  of  deeper  parts  (crura  cerebri).  We  shall 
discuss  phenomena  which  are  somewhat  similar  when  the 
cerebellum  is  under  discussion  ;  but  we  have  as  yet  no  posi- 
tive knowledge  of  the  physiological  connections  between  the 
optic  lobes  and  the  cerebellum. 

The  sense  of  sight  has  a  marked  effect  upon  co-ordination 
of  movement,  as  we  all  know.  Dizziness  often  follows  the 
close  inspection  of  a  water-fall,  or  the  rapid  flight  of  objects 
before  the  eyes.  The  effect  of  extreme  elevation  from  sur- 
rounding objects  frequently  produces  marked  disturbances  of 
equilibrium.  These  facts  seem  to  sustain  the  belief  that  the 
optic  fibers  must  be  closely  associated  with  the  cerebellum, 
pons  Varolii,  or  crura,  and  the  discovery  of  Flourens  is  an 
additional  argument  in  its  favor. 

Finally,  it  is  believed  by  some  that  a  center  which  presides 
over  the  secretion  of  sweat  is  situated  somewhere  in  the  region 
of  the  corpora  quadrigemina. 

A  SUMMARY   OF  THE   EFFECTS   OF  LESIONS   OF  THE   OPTIC   CENTERS 
AND   OPTIC    NERVES. 

In  connection  with  the  discussion  of  the  corpora  quadri- 
gemina and  the  probable  course  and  distribution  of  the 
nerves  of  sight,  it  seems  to  me  an  appropriate  time  to  mention 
some  interesting  phenomena  pertaining  to  vision  which  have 
an  important  bearing  upon  the  localization  of  intra- cranial 
lesions.  Before  doing  so,  however,  it  will  be  necessary  to 
hastily  review  a  few  important  facts  which  are  essential  to  a 
complete  understanding  of  the  subject. 

The  optic  apparatus  may  be  said  to  comprise  the  follow- 
ing parts : 

1.  Certain  cortical  centers,  which  act  as  the  interpreters 
of  visual  sensations  transmitted  to  the  convolutions  by  means 
of  the  nerve  fibers  within  the  white  substance  of  the  cerebral 
hemispheres.  These  centers  probably  transform  all  impulses 
(which  start  originally  as  retinal  impressions)  into  conscious 
visual  perceptions. 


GANGLIA    OF  THE  OPTIC  APPARATUS,  183 

2.  Nodal  masses  of  gray  matter,  with  which  the  optic 
nerve  fibers  are  intimately  associated  before  entering  the 
white  substance  of  the  cerebral  hemisphere.  These  masses 
include  the  corpora  quadrigemina,  the  corpora  geniculata, 
the  corpus  sub-thalamicum,  the  optic  center  of  the  thalamus 
(Luys),  the  basal  optic  ganglion  (Meynert),  and  probably 
some  centers  situated  within  the  medulla  oblongata. 

These  interrupting  ganglia  probably  exercise  a  modifying 
influence  of  some  kind  upon  the  impulses  which  are  con- 
ducted to  them  from  the  retinae  ;  and  subsequently  allow 
them  to  pass  to  the  cells  of  the  cerebral  convolutions  so 
altered  or  materialized  as  to  be  readily  transformed  into 
conscious  perceptions  of  external  objects  recognized  by  the 
eyes.  It  is  not  known  what  the  special  function  of  each  of 
these  interrupting  masses  is,  nor  can  it  be  determined  except 
through  a  more  complete  knowledge  of  cerebral  architecture 
and  pathology  than  we  now  possess. 

3.  Nerve  fibers  witJiin  the  optic  nerves  and  the  optic 
tracts — the  latter  being  the  prolongation  of  the  former  behind 
the  chiasm  (see  Fig.  43).  These  fibers  convey  all  impressions 
made  by  objects  external  to  the  body  upon  the  retinae,  by 
means  of  the  organ  of  sight,  to  the  interrupting  masses  of 
gray  matter  mentioned  above.  The  waves  of  light,  which 
enter  the  pupil  and  fall  upon  the  retina,  create  in  the  struct- 
ural elements  of  that  membrane  (probably  in  the  so-called 
''  rods"  and  ''  cones  of  Jacob")  impulses  which  are  conveyed 
by  means  of  the  optic  fibers  to  the  interrupting  ganglion  cells, 
and  then  to  the  convolutions  of  the  cerebral  hemisphere 
where  these  impulses  become  sight-impressions.  It  is  evi- 
dent, therefore,  that  anything  which  tends  to  interfere  with 
the  perfect  conducting  power  of  these  fibers  will  impair  the 
power  of  accurate  conception  of  external  objects  revealed  to 
us  by  means  of  vision,  because  the  cortical  centers  are  cut  off 
from  their  retinal  connections  ;  hence  the  study  of  the  course 
of  the  nerve  fibers  and  the  relations  of  the  nerve  tracts  to  sur- 
rounding parts  becomes  of  vital  importance  to  the  advanced 
neurologist  (the  diagnosis  of  many  cerebral  and  intercranial 


184  THE  BRAIN. 

lesions  resting  entirely  or  in  part  upon  optic  phenomena 
which  are  to  be  interpreted  from  an  anatomical  standpoint 
alone). 

4.  The  retina^  and  its  various  structural  elements.  This 
membrane  constitutes  the  peripheral  portion  of  the  nervous 
optic  apparatus.  It  is  the  only  place  in  the  body  where  the 
nervous  system  is  so  exposed  as  to  admit  of  a  direct  examina- 
tion, since  we  can  see  it  by  aid  of  the  ophthalmoscope,  and 
thus  study  its  diseased  conditions  as  well  as  its  appearance  in 
health.  Physiologically,  it  is  to  be  considered  as  the  sen- 
sitive plate  from  which  the  details  of  outline  and  color  of 
external  objects  are  telegraphed  to  the  convolutions  of  the 
cerebrum. 

The  experiments  of  Flourens,  already  quoted,  first  demon- 
strated that  a  crude  sense  of  vision  remains  in  animals  which 
have  been  deprived  of  their  cerebral  convolutions  above  the 
level  of  the  corpora  quadrigemina,  and  many  subsequent 
observers  have  attested  to  the  accuracy  of  his  conclusions. 
These  experiments  point  to  some  functions  within  the  masses 
of  gray  matter  that  are  associated  with  the  optic  fibers,  which 
bear  a  close  analogy  to  those  of  the  cortical  cells  of  the  so- 
called  '*  visual  area"  of  the  hemispheres.  We  are  forced  to 
accept  the  view  that  these  ganglionic  masses  take  cognizance 
of  visual  impulses  in  an  imperfect  way,  although  the  cerebral 
convolutions  seem  to  be  essential  to  a  complete  transforma- 
tion of  visual  impulses  into  conscious  sight-perceptions.  Sec- 
tion of  the  optic  fibers  after  they  leave  the  brain  invariably 
destroys  sight,  thus  proving  that  the  retina  itself  has  no  in- 
herent power  of  interpreting  visual  impressions  which  are  cast 
upon  it. 

Now,  from  what  has  been  stated,  we  can  classify  lesions 
which  may  affect  or  destroy  the  visual  function  as  follows : 

1.  Lesions  of  the  retina,  or  of  some  of  the  other  struct- 
ures of  the  visual  apparatus  which  prevent  the  formation  of 
images  within  it. 

2.  Lesions  of  the  optic  nerve,  anteriorly  to  the  chiasm,  at 
which  point  the  decussating  fibers  have  crossed  each  other. 


INTRA-GRANIAL  LESIONS  AFFECTING  SIGHT. 


185 


3.  Lesions  of  the  optic  tracts  and  the  chiasm.,  or  of  parts 
so  adjacent  to  them  as  to  create  pressure  upon  the  optic 
fibers. 

4.  Lesions  of  those  gangltonic  masses  whose  connection 
with  the  optic  fibers  has  been  demonstrated  by  anatomical  or 
pathological  research. 

5.  Lesions  of  certain  regions  of  the  cortex  cerebri.,  which 
have  been  shown  to  be  in  intimate  association  with  vision. 


Fig.  42, — A  diagram  designed  by  the  author  to  show  some  of  the  relations  of  the  optic 
and  olfactory  nerve  fibers  to  surrounding  parts. 

F,  frontal  lobes  of  cerebrum  ;  P,  parietal  lobe ;  T,  temporo-sphenoidal  lobe  ;  S,  fissure  of 
Sylvius ;  R,  fissure  of  Rolando ;  0,  occipital  lobe ;  C,  cerebellum ;  M,  medulla  ob- 
longata ;  1,  olfactory  nerve ;  2,  optic  chiasm  ;  3,  motor-oculi  nerve ;  4,  corpora  quad- 
rigcmina ;  5,  trigeminus  nerve ;  a,  basis  cruris  ;  6,  tegmentum  cruris.  The  diamonds 
in  the  occipital  lobe,  the  cortical  visual  centers  of  Munk.  The  cerebellum  and  pons 
Varolii  are  shown  as  if  separated  from  the  cerebrum,  in  order  to  make  the  relations 
of  the  crus  to  the  optic  tracts  apparent.  This  diagram  should  be  compared. with 
Fig.  43  to  make  its  bearings  upon  cerebral  localization  apparent. 

6.  Lesions  of  the  internal  capsule  of  the  cerebrum  ;  or  of 
such  parts  of  the  medullary  center  of  each  hemisphere  as  con- 
tain fibers  connected  with  the  ''visual  area"  of  the  cortex. 

The  first  set  of  causes  of  impairment  of  vision  enumer- 
ated above  belongs  properly  to  the  province  of  the  oculist 


186  THE  BRAIN. 

rather  than  of  the  neurologist,  although  there  is  one  con- 
dition which  should  always  be  sought  for  when  cerebral 
disease  is  suspected,  viz.,  neuro-retinitis,  or  the  so-called 
'''choked  disky  The  evidences  of  this  condition  are  afforded 
by  the  ophthalmoscope  alone,  because  vision  is  not  impaired 
in  the  early  stages.  Its  existence  is  recognized  early  by  tor- 
tuosity of  the  veins  of  the  fundus  of  the  eye,  swelling  of  the 
optic  nerve,  and  obscureness  of  the  margin  of  the  disk ;  later, 
the  outline  of  the  disk  becomes  unnaturally  sharp  and  dis- 
tinct, the  nerve  atrophies,  the  vessels  become  very  small,  the 
fundus  is  unnaturally  pale,  and  vision  is  impaired.  This  con- 
dition is  always  (?)  bilateral,  although  it  is  not  uncommon  to 
note  a  marked  difference  in  the  severity  of  the  changes  in 
the  two  eyes.  Special  attention  is  called  to  this  disease  of 
the  eye,  because  it  is  now  considered  as  one  of  the  most  reli- 
able signs  of  conditions  of  the  cerebrum  which  tend  to  pro- 
duce a  gradually  increasing  pressure^  particularly  of  tumors ; 
and,  in  the  second  place,  because  its  existence  is  liable  to  be 
overlooked,  since  vision  is  not  impaired  early. 

The  various  phenomena  which  are  due  to  paresis  of  ocu- 
lar muscles,*  and  which  have  often  the  most  positive  value  in 
definitely  localizing  cerebral  disease,  can  not  be  considered 
under  this  set  of  symptoms  or  in  this  connection,  because 
they  do  not  govern  in  any  way  the  sense  of  sight,  although 
they  assist  the  eye  to  focus  images  of  objects  upon  the  retina. 
My  friend  Dr.  W.  C.  Ayers  has  lately  made  a  valuable  con- 
tribution to  medical  literature  in  the  form  of  a  brochure  upon 
the  value  of  the  ophthalmoscope  as  an  aid  in  general  diagno- 
sis," which  may  well  be  consulted  by  all  who  desire  practical 
information  in  regard  to  the  utility  of  this  instrument,  and 
the  intimate  relationship  which  exists  between  the  eye  and 
the  body,  as  revealed  by  clinical  study. 

The  second  set  of  causes  of  impairment  of  vision  (lesions 
of  the  optic  nerve  anteriorly  to  the  chiasm)  includes  chiefly 

'  These  will  be  found  by  consulting  subsequent  pages  which  relate  to  the  motor 
oculi  nerve. 

»  "American  Journal  of  the  Medical  Sciences,"  October,  1882. 


CEREBRAL  LESION'S  AFFEGTIN'a  SIGHT.  187 

those  conditions  within  the  orbit  wMcli  create  pressure 
upon,  or  destruction  of,  the  optic  nerve  after  it  leaves  the 
cavity  of  the  cranium.  It  is  evident  from  the  diagram  (Fig. 
43)  that  the  impairment  of  sight  in  this  case  will  be  confined 
exclusively  to  one  eye.  The  phenomena  produced  by  disease 
within  the  cavity  of  the  orbit  upon  sight  must,  of  course, 
depend  upon  the  amount  of  injury  done  to  the  optic  nerve. 
Blindness  of  one  eye  indicates,  as  a  rule,  some  exciting  cause 
outside  of  the  cavity  of  the  cranium.  Remember  that  neither 
true  amblyopia  or  total  blindness  of  one  eye  occur  in  con- 
nection with  pressure  upon  the  optic  nerve  fibers  either  at 
the  chiasm  or  behind  it. 

We  come  now  to  the  third  set  of  causes  enumerated  on 
page  184,  viz.,  lesions  of  the  optic  tracts  and  chiasm.  This 
set  includes  not  only  actual  lesions  of  the  nerve,  but  also 
pressure-effects  exerted  upon  the  optic  fibers  by  lesions  of 
adjacent  structures.  Before  we  pass  to  the  consideration  of 
the  diagnostic  symptoms  of  this  condition,  it  is  important 
that  we  review  some  of  the  relations  of  the  optic  chiasm  and 
the  optic  tracts. 

If  we  trace  the  optic  nerve  fibers  from  behind  forward,  we 
find  that  the  optic  tracts  appear  to  arise  from  the  optic  thai- 
ami,  the  superior  quadrigeminal  bodies,  and  the  corpora  ge- 
niculata.  As  they  leave  the  under  surface  of  the  thalami,  they 
make  a  sudden  bend  forward  and  curve  around  the  crura 
cerebri  in  the  form  of  a  flattened  band  (Fig.  43).  At  their 
anterior  portions  the  tracts  become  closely  attached  to  the 
crura,  and,  in  the  region  of  the  tuber  cinerium,  an  accession 
of  fibers  to  the  tracts  may  be  demonstrated.  Before  the 
chiasm  is  reached  the  tracts  become  more  cylindrical  in 
form. 

The  optic  commissure,  or  chiasm,  is  about  half  an  inch 
long  in  its  transverse  measurement,  and  lies  upon  the  olivary 
process  of  the  sphenoid  bone.  The  internal  carotid  arteries 
lie  in  close  relation  with  it  at  the  sides,  and  the  anterior  cere- 
bral arteries,  with  their  communicating  branch,  are  so  dis- 
posed as  to  constitute  what  might  be  called  a  loop  about  the 


188  THE  BRAIK 

optic  nerves.  The  clinical  bearing  of  this  fact  will  be  dis- 
cussed later.  Henle  reports  a  few  remarkable  instances  where 
the  chiasm  was  wanting,  the  optic  tracts  being  continued 
without  interruption  to  the  eyeball  of  the  corresponding  side ; 
but  these  abnormalities  are  so  rare  as  to  be  of  no  practical 
importance  from  a  clinical  standpoint. 

We  are  now  able  to  study  the  diagram  which  I  draw  upon 
the  blackboard,  and  to  properly  interpret  the  clinical  deduc- 
tions which  may  be  drawn  from  it.  It  is  intended  to  portray 
the  effects  of  localized  pressure  upon  the  optic  chiasm  and 
optic  tracts,  as  well  as  those  of  destructive  lesions  of  the  same, 
and  of  the  '* internal  capsule"  of  the  brain. 

Now,  this  diagram  is  designed  chiefly  to  portray  the 
mechanism  of  one  peculiar  symptom,  and  the  use  to  which  it 
may  be  employed  by  the  neurologist  in  definitely  determining 
the  seat  of  the  disease-lesion  which  is  creating  it.  I  refer  to 
'^hemianopsia,^''  or  blindness  of  one  lateral  half  of  the  retinal 
The  term  ''  hemiopia"  is  often  employed  to  express  the  same 
condition,  although  it  is  to  my  mind  a  poor  one,  since  it  sim- 
ply means  ''half  vision,"  and  thus  fails  to  express  the  idea 
intended. 

The  following  steps  are  commonly  employed  to  detect  the 
existence  of  this  symptom :  Request  the  patient  to  close  one 
eye  by  pressing  the  lid  down  with  the  finger,  and  to  so  direct 
the  open  eye  as  to  concentrate  its  gaze  upon  some  fixed  object 
near  to  it.  [I  usually  hold  up  the  forefinger  of  my  own  hand 
within  a  foot  of  the  patient's  open  eye,  and  tell  him  to  look 
steadily  at  it.]  Having  done  this,  take  some  object  which  is 
easily  seen  (such  as  a  small  piece  of  white  paper)  in  the  unem- 
ployed hand,  and  move  it  to  the  right  and  left  of  the  object 
upon  which  the  patient  is  gazing,  and  also  above  and  below 
the  object,  asking  the  patient,  in  each  case,  if  the  two  objects 
are  seen  simultaneously  and  with  distinctness,  and  notice  upon 
which  side  of  the  fixed  object  the  patient  can  not  perceive  the 
moving  object.  It  is  self-evident  that  the  retina  is  blind  upon 
the  side  opposite  to  that  upon  which  the  moving  object  is  lost 

»  This  eymptom  will  be  discussed  very  fully  in  the  second  section  of  this  work. 


CEREBRAL  LESIONS  AFFEGTING  SIGHT, 


189 


J   Optic 
( chiasm. 


Superior  corpus 
uadrigeminus,  or 
e  "pulvinar." 


j  Eight  ti-act  of 
I     Wernicke. 


Visual  area  of  cor-  (^ 
tex  of  left  cerebral  ^"^ 
hemisphere. 


Visual  area  of  cor- 
tex of  right  cerebral 
hemisphere. 


Fig.  43. — A   diagram  designed  hy  the  author  to  illustrate  the  latest  views  in  reference 
to  the  course  of  the  optic  nerve  fibers. 

The  dotted  lines  (A  and  B)  arise  from  the  left  hemisphere ;  the  continuous  lines  (C  and  D) 
arise  from  the  right  hemisphere.     It  will  be  perceived  that  the  occipital  cortex  of 

»the  left  hemisphere  is  shown  to  be  connected  with  the  left  half  of  each  eye,  and  the 
right  hemisphere  with  the  right  half  of  each  eye.  The  diagram  also  shows  that  the 
fibers  of  each  optic  tract  pass  through  the  external  geniculate  body,  the  superior 
corpora  quadrigemina,  or  the  pulvinar  of  the  thalamus,  before  they  radiate  to  the 
occipital  cortex ;  1,  2,  3,  4,  5,  indicate  the  various  localities  where  lateral  homony- 
mous hemianopsia  can  be  produced ;  C,  G,  E,  the  external  geniculate  body ;  C,  G,  I, 
internal  geniculate  body. 

15 


190  TEE  BRAIN. 

to  sight.  The  visual  area  can  also  be  accurately  drawn  by 
means  of  a  perimeter  if  it  is  deemed  advisable. 

The  most  common  form  of  hemianopsia  is  that  in  which 
the  nasal  half  of  one  eye  and  the  temporal  half  of  the  other 
is  blind,  this  condition  being  the  result  of  injury  done  to 
parts  posterior  to  the  chiasm.  When  the  chiasm  is  affected 
we  commonly  meet  the  hi-nasal  type. 

There  is  still  one  more  form  which  is  occasionally  encount- 
ered, viz.,  the  hi-temporal  type.  This  has  been  interpreted 
by  an  autopsy  made  upon  a  case  intrusted  to  the  care  of 
Prof.  H.  Knapp,  of  this  city.  It  must  be  evident  that  the 
chances  would  be  extremely  small  of  ever  encountering  a  bi- 
lateral lesion  which  would  affect  only  those  fibers  of  the  optic 
chiasm,  or  optic  tract,  which  supply  the  temporal  half  of  each 
retina,  and  at  the  same  time  leave  the  decussating  fibers  in- 
tact. How,  then,  are  we  to  account  for  the  fact  that  this  form 
is  sometimes  met  with?  In  the  preceding  portion  of  this 
lecture  I  called  your  attention  to  a  peculiar  arrangement  of 
the  arteries  in  the  region  of  the  optic  chiasm.  Now,  it  has 
been  shown  that  atheromatous  degeneration  of  the  ''  circle  of 
Willis "  (a  peculiar  arrangement  of  blood-vessels  at  the  base 
of  the  brain)  so  impairs  the  elasticity  of  the  arteries  as  to 
cause  the  pulsations  of  the  carotids  to  aid  in  creating  a  type 
of  injury  to  the  chiasm,  so  limited  in  its  extent  as  to  impair 
only  the  fibers  distributed  to  the  temporal  halves  of  the 
retinae,  and  thus  to  create  bi-temporal  hemianopsia. 

We  may,  therefore,  summarize  the  clinical  significance  of 
this  peculiar  form  of  blindness  as  follows : 

{a)  The  lateral  homonymous  variety  (where  the  left  or 
right  half  of  each  eye  is  simultaneously  affected)  indicates 
lesions  affecting  the  optic  tract  or  its  prolongations  through 
the  brain-substance  to  the  cortex  of  the  occipital  lobes  (the 
cortical  centers  of  Munk). 

ip)  The  hi-nasal  variety  indicates  a  lesion  pressing  upon 
the  central  portion  of  the  chiasm. 

{&)  The  hi'temporal  variety  indicates,  as  a  rule,  atheroma- 
tous degeneration  of  the  circle  of  Willis.     Possibly  (?)  sym- 


CEREBRAL  LESION'S  AFFECTING  SIOET.  191 

metrical  lesions  of  the  outer  part  of  the  chiasm  might  also 
cause  it.  The  view  of  Charcot,  that  a  decussation  of  the 
optic  fibers  takes  place  within  the  substance  of  the  corpora 
quadrigemina,  is  not  sustained  by  a  recorded  case  of  bi-tem- 
poral  hemianopsia  produced  by  a  circumscribed  lesion  within 
those  bodies,  and  can  be  dismissed  as  incorrect. 

{d)  Finally,  lesions  of  the  internal  capsule  are  sometimes 
associated  with  lateral  homonymous  Jiemianopsia. 

The  bi-nasal,  and  also  the  bi- temporal,  varieties  are  due  (as 
a  rule,  at  least)  to  lesions  confined  to  the  anterior  fossa  of 
the  cranium  ;  hence  we  sometimes  find  the  olfactory  nerve  of 
the  side  corresponding  to  the  seat  of  the  lesion  simultaneously 
affected,  and  creating  anosmia  (loss  of  smell)  with  or  without 
subjective  odors. 

If  the  lesion  be  situated  within  the  middle  fossa  of  the 
cranium,  the  optic  tracts  may  be  affected,  thus  causing  lateral 
homonymous  hemianopsia,  while  the  motor  nerves  of  the  eye 
may  be  simultaneously  pressed  upon  as  they  pass  through 
that  fossa  on  the  way  to  their  foramen  of  exit  from  the  cra- 
nium (the  sphenoidal  fissure),  thus  producing  more  or  less 
impairment  of  the  movements  of  the  eyeball  of  the  same  side. 
The  value  of  these  complications  cannot  be  over-estimated, 
when  they  exist,  because  they  are  of  the  greatest  aid  in  diag- 
nosis, and  often  enable  a  skilled  anatomist  to  positively  deter- 
mine the  seat  of  the  lesion. 

The  fourth!  set  of  causes  of  impairment  of  vision  (according 
to  the  classification  given  on  page  184)  comprises  all  diseased 
conditions  which  are  limited  exclusively  to  those  ganglionic 
masses  through  which  the  optic  fibers  pass  in  order  to  reach 
their  connections  with  the  convolutions  of  the  cerebrum.  If 
we  confine  ourselves  to  this  strict  limitation,  we  are  forced  to 
admit  that  little  can  positively  be  said  respecting  them  which 
will  bear  upon  intra-cranial  diagnosis,  because,  to  my  knowl- 
edge, there  are  no  recorded  cases  where  evidences  of  cerebral 
disease  have  been  confined  exclusively  to  these  regions. 

There  are  some  symptoms,  however,  that  may  coexist  with 
disturbances  of  vision  when  lesions  exist  in  parts  contained 


192  THE  BRAIN. 

within  the  middle  fossa  of  the  skull ;  these  may  prove  of 
assistance  in  deciding  as  to  the  seat  of  the  lesion.  Among 
them  may  be  enumerated :  1.  Crossed  paralysis  of  the  "  tJiird 
nerve  and  body'''  type,  a  condition  characterized  by  hemi- 
plegia and  paralysis  of  the  motor-oculi  nerve  of  the  opposite 
side.  2.  Crossed  paralysis  of  the  ^'olfactory  nerve  and 
body  "  type,  a  condition  characterized  by  hemiplegia  and  loss 
of  smell  in  the  opposite  nostril.  3.  Hemiplegia^  or  loss  of  the 
power  of  voluntary  motion  in  one  lateral  half  of  the  body.  4. 
HemiancBsthesia^  or  a  loss  of  sensation  in  one  lateral  half  of 
the  body.  5.  Ataxic  symptoms,  indicating  an  impairment  of 
coordination  of  muscular  movements. 

The  first  of  these  points  positively  to  a  lesion  of  the  cms 
cerebri,  if  unattended  by  other  symptoms.  But,  if  evidences 
of  disturbance  of  the  optic  tract  (lateral  homonymous  hemia- 
nopsia) exists  simultaneously  with  this  form  of  crossed  pa- 
ralysis, it  indicates  that  the  lesion  is  large  enough  to  interfere 
also  with  the  optic  nerve,  as  well  as  the  motor-oculi  fibers 
within  the  crus  and  the  motor  tract  of  the  cms.  The  symp- 
toms of  this  variety  of  crossed  paralysis  are  so  well  defined 
as  to  render  it  almost  impossible  to  mistake  them. 

The  second  condition  (crossed  paralysis  of  the  olfactory 
nerve  and  body  type)  may  occur  when  the  lesion  is  sufficient- 
ly large  to  create  pressure  upon  the  motor  tracts  of  the  brain, 
thus  causing  hemiplegia  of  the  opposite  side,  and  at  the  same 
time  to  injure  the  olfactory  nerve,  thus  causing  anosmia  (loss 
of  smell)  in  the  nostril  of  the  corresponding  side.  Of  course 
the  optic  tract  or  chiasm  must  be  involved  simultaneously 
when  hemianopsia  also  exists.  The  tests  for  anosmia  will  be 
given  in  a  subsequent  section  of  this  work. 

Hemiplegia  may  occur  in  connection  with  hemianopsia 
when  the  lesion  is  of  sufficient  size  to  affect  any  part  of  the 
so-called  ^^  motor  tracV  simultaneously  with  the  optic  nerve 
fibers.  The  motor  paralysis  is  chiefly  manifested  on  the  side 
opposite  to  the  lesion ;  because  the  fibers  of  the  motor  tract 
decussate  at  the  lower  part  of  the  medulla.  Flechsig  has 
shown  that,  in  rare  cases,  exceptions  to  this  general  rule  are 


CROSSED  PARALYSIS  WITH  HEMIANOPSIA. 


193 


to  be  explained  by  an  abnormality  in  the  decussation  of  the 
motor  fibers.  Hemiplegia  is  now  and  then  observed  in  con- 
nection with  hemianopsia ;  although  the  olfactory,  motor- 
oculi,  trigeminus,  and  facial  nerve  roots  are  equally  liable  to 
be  simultaneously  involved.     This  explains  the  mechanism  of 


VISUAL  AREA. 


Fig.  44. — A  diagram  designed  by  the  author  to  show  the  general  course  of  fibers  in  the 
*■'■  sensory''"'  and  '■'■  motor  tracts,''''  and  their  relation  to  co'tain  fasciculi  of  the  optic 
nerve  tracts.     (Modified  from  Seguin.) 

S,  sensory  tract  in  posterior  region  of  mesocephalon,  extending  to  0  and  T,  occipital  and 
temporal  lobes  of  hemispheres ;  M,  motor  tract  in  basis  cruris,  extending  to  P  and 
F,  parietal  and  (part  of)  frontal  lobes  of  hemispheres ;  C  Q,  corpus  quadrigeminum ; 
0  T,  optic  thalamus ;  N  L,  nucleus  Icnticularis ;  N  C,  nucleus  caudatus ;  1,  the  fibers 
forming  the  "  tegmentum  cruris  "  (Meynert) ;  2,  the  fibers  forming  the  "  basis  cruris  " 
(Meynert) ;  a,  fibers  of  the  optic  nerve  which  become  associated  with  the  "  optic  cen- 
ter" in  the  optic  thalamus,  and  are  subsequently  prolonged  to  the  "visual  area"  of 
the  convolutions  of  the  cerebrum  ;  6,  optic  fibers  which  join  the  cells  of  the  "  cor- 
pora quadrigemina,"  and  are  then  prolonged  to  the  visual  area  of  the  cerebral  cortex. 


the  four  varieties  of  ''crossed  paralysis"  which  are  encoun- 
tered, the  hemiplegia  being  on  the  side  opposite  to  the  lesion, 
and  the  symptoms  produced  by  paralysis  of  the  cranial  nerve 
being  confined  to  the  side  corresponding  to  the  lesion. 

HemiancBsthesia  indicates  some  disturbance  of  the  nerve 
fibers  of  the  so-called  ''sensory  tracV ;  the  loss  of  sensation 
being  confined  to  the  lateral  half  of  the  body  opposite  to  the 
lesion  which  causes  it,  because  the  sensory  fibers  decussate  in 
the  spinal  cord.  In  cerebral  hemiansesthesia  there  is  more  or 
less  insensibility  to  touch,  pain,  and  temperature,  and  also 


194  THE  BRAIK 

abolition  of  muscular  sensibility  with  complete  retention  of 
electro-motor  contractility.  The  mucous  membranes  of  the 
eye,  nose,  and  mouth  are  also  anaesthetic.  Now  the  upper 
portion  of  the  sensory  tract  lies  in  the  posterior  regions  of  the 
crus  cerebri  and  the  internal  capsule,  and  is  in  close  relation 
with  the  posterior  basal  ganglia.  The  fibers  of  the  optic  tract 
may  be  likewise  affected  simultaneously  with  lesions  of  the 
following  parts:  The  crus,  the  internal  capsule,  the  optic 
thalamus,  the  corpora  qnadrigemina,  the  geniculate  bodies, 
and  the  medulla.  Our  ability  to  definitely  locate  lesions  of 
the  sensory  tract,  or  of  the  ganglia  connected  with  it,  is  as 
yet  imperfect.  It  is  only  by  the  careful  study  of  associated 
symptoms  that  conclusions  can  be  arrived  at. 

Ataxic  manifestations^  occurring  in  connection  with  evi- 
dences of  impairment  of  the  sense  of  sight,  open  a  wide  field 
for  speculation.  The  proximity  and  intimate  structural  rela- 
tions of  the  cerebellum  with  the  corpora  quadrigemina,  basal 
ganglia,  crus,  and  medulla,  suggest  the  possibility  of  cerebel- 
lar lesions  when  these  two  symptoms  are  present  to  a  marked 
degree.  The  subject  is  too  complex  for  discussion  here.  It 
will  be  more  intelligible  after  the  cerebellum  has  been  con- 
sidered. 

The  fifth  set  of  causes  of  impairment  of  vision  previously 
tabulated  on  page  184  will  now  be  considered.  Within  the 
past  few  years  the  attention  of  physiologists  has  been  direct- 
ed, by  some  remarkable  results  of  experimentation  upon  the 
convolutions  of  the  cerebral  cortex,  toward  the  view  that  cer- 
tain convolutions  of  the  cerebrum  were  essential  to  perfect 
visual  perceptions.  To  Flourens  and  some  of  the  older  ob- 
servers, who  had  remarked  that  the  removal  of  portions  of 
the  hemispheres,  or  serious  injury  to  them,  created  blindness, 
the  loss  of  sight  appeared  to  be  temporary.  The  statement 
was  explained  in  various  ways,  until  Goltz  called  attention  to 
the  error  of  supposing  that  no  permanent  imperfections  of 
vision  remained  after  extensive  injuries  to  the  cerebral  hemi- 
spheres. This  author  showed  that  the  permanent  results  of 
such  injuries  might  escape  notice  unless  special  care  was  used 


i 


PSYCHICAL  BLINDNESS.  195 

in  the  examinations  of  the  animal.  The  peculiarities  of  the 
permanent  impairment  of  vision  are  manifested  only  when 
the  animal  is  subjected  to  tests  which  had  been  invariably 
potent  before  the  cerebral  injury.  Thus  the  dog,  from  which 
portions  of  the  cerebral  hemispheres  had  been  removed,  fails 
to  recognize  his  food  by  sight ;  when  he  is  threatened  by  a 
whip  he  is  not  cowed ;  he  is  no  longer  affected  by  objects 
which  caused  him  to  be  violently  excited  before  the  mutila- 
tion ;  he  makes  no  response  to  the  extension  of  the  hand  of 
his  master  for  the  paw  ;  and  yet  this  animal  can  see  to  avoid 
objects  and  to  perform  all  varieties  of  movement  as  well  as  in 
his  natural  condition.  Another  striking  characteristic  of  this 
impairment  of  sight  is,  that  under  educational  exercise  recov- 
ery takes  place.  The  dog  may  again  be  taught  to  fear  casti- 
gation  and  to  shrink  at  the  sight  of  the  whip ;  to  recognize 
his  food  ;  to  obey  the  motion  of  his  master's  hand,  etc. 

Two  interpretations  of  these  phenomena  have  been  sug- 
gested :  The  first  is,  that  the  animal  has  imperfect  visual 
perceptions,  so  that  objects  appear  misty  or  as  if  seen  through 
a  gauze.  Goltz  suggests  that  they  may  appear  as  if  all  the 
colors  were  washed  out,  thus  depriving  food,  dress,  etc.,  of 
their  characteristic  appearances.  The  second  interpretation 
supposes  that  the  memory  of  past  visual  impressions  is  ef- 
faced, so  that  the  animal  forgets  the  pain  of  the  lash,  the  taste 
of  the  food,  the  features  of  his  master,  the  tricks  which  have 
been  laboriously  taught  him*  The  first  view  is  that  of  Goltz, 
who  considers  that  the  animal  has  to  learn  to  use  his  imper- 
fect visual  perceptions  before  his  intellectual  faculties  (which 
are  presumed  to  be  unimpaired)  can  respond  to  them  in  a 
proper  way.  The  second  view  is  that  of  Munk,  who  speaks 
of  this  form  of  imperfect  vision  as  "psychical  blindness,"  in 
contrast  to  "absolute  blindness,"  which  is  the  result  of  de- 
struction of  the  optic  fibers.  The  condition  of  the  animal 
resembles  that  of  the  new-born.  Retinal  impressions  have 
DO  associations  connected  with  them.  During  the  period  of 
recovery  the  animal  has  to  acquire  a  new  memory,  as  it 
were. 


196  THE  BRAIK 

With  this  distinction  clearly  in  mind,  we  are  prepared  to 
discuss  the  views  of  Ferrier,  Goltz,  Munk,  Luciani,  Tamburini, 
Yeo,  Dalton,  and  others  respecting  the  exact  seat  of  the  visual 
centers  within  the  cortex  cerebri. 

Goltz,  in  his  experiments  upon  dogs,  was  unable  to  recog- 
nize any  distinct  areas  which  presided  exclusively  over  visual 
impressions.  He  insists  that  disturbances  of  general  sensibil- 
ity accompanied  the  impairment  of  vision  produced  by  de- 
struction of  the  convolutions,  and  that  the  results  depended 
upon  the  amount  of  brain-substance  removed  or  destroyed. 
He  found,  however,  that  the  locality  operated  upon  influenced 
the  phenomena  which  followed,  and  that  recovery  would  take 
place  if  the  injury  was  not  too  extensive.  Goltz  destroyed 
the  brain  by  making  a  hole,  or  a  number  of  them,  through 
the  skull,  and  using  a  forcible  stream  of  water  to  wash  away 
the  brain-substance.  The  faults  of  the  method  may  account 
for  the  negative  results  obtained  by  it. 

Ferrier  investigated  the  subject  chiefly  upon  the  monkey 
tribe  (the  nearest  approach  to  the  human  race)  and  arrived  at 
conclusions  of  a  more  positive  character.  This  observer  was 
led  to  adopt  a  more  certain  way  of  limiting  the  injury  done  to 
the  cortex  than  that  of  Goltz.  His  conclusions  may  be  thus 
summarized:  When  the  ''angular  gyrus" — a  convolution  of 
the  parietal  lobe,  so  called  from  its  shape,  since  it  forms  a 
sharp  angle  (see  Fig.  22) — was  destroyed  upon  one  side  only, 
the  vision  of  the  opposite  eye  was  destroyed  for  a  time,  but  it 
eventually  regained  its  powers.  If  the  angular  gyrus  of  each 
hemisphere  was  simultaneously  destroyed,  the  loss  of  sight 
was  permanent  and  both  eyes  were  equally  affected.  Hence 
it  would  appear  that  each  hemisphere  is  in  some  way  con- 
nected with  both  eyes,  because  unilateral  destruction  of  this 
convolution  does  not  create  permanent  blindness,  as  it  would 
do  if  the  opposite  hemisphere  did  not  come  to  its  relief.  Dal- 
ton has  lately  confirmed  the  views  of  Ferrier  by  experiments 
made  upon  dogs,  thus  tending  to  confute  the  view  of  Goltz 
that  the  effects  of  cortical  lesions  depend  more  on  their  extent 
than  on  their  position.     The  animals  operated  upon  by  this 


THE  CORTICAL  AREA    OF  VISION.  197 

observer  remained  permanently  blind,  although  the  lesion  was 
unilateral. 

Munk,  on  the  other  hand,  has  confined  his  experiments 
chiefly  to  the  occipital  lobes  of  the  cerebrum,  and  has  appa- 
rently demonstrated  the  existence  of  a  "visual  area,"  differ- 
ing in  position  and  of  much  wider  extent  than  that  of  Ferrier. 
He  maintains  that  certain  parts  of  this  region  can  be  shown 
to  preside  over  limited  portions  of  the  retina,  and  that  blind- 
ness of  circumscribed  spots  in  the  retina  can  be  artificially 
produced.  He  states  that  the  *' absolute  blindness"  thus  cre- 
ated is  commonly  associated  with  ''psychical  blindness,"  from 
which  the  animal  may  recover  by  proper  exercise  and  train- 
ing, provided  the  whole  visual  area  is  not  destroyed.  This 
author  attributes  the  recovery  to  a  deposition  of  new  visual 
experiences  in  the  rest  of  the  visual  area.  The  view  advanced 
by  Munk  is  now  quite  generally  accepted  as  the  true  one. 
The  optic  fibers  pass  closely  to  the  cortex  of  the  angular 
gyrus  in  order  to  reach  the  occipital  lobe.  Ferrier  and  Dal- 
ton  probably  severed  them. 

The  sixth  set  of  causes  of  impairment  of  vision,  previously 
tabulated  on  page  184,  has  been  discussed  in  part  in  connec- 
tion with  the  others.  We  have  a  mass  of  clinical  as  well  as 
experimental  evidence  to  show  that  destructive  lesions  situ- 
ated within  the  posterior  one  third  of  the  internal  capsule 
cause  h^miancBsthesia  on  the  opposite  side  of  the  body. 

As  regards  vision,  the  symptoms  which  sometimes  exist 
are  especially  noteworthy.  There  appears  to  be  developed  on 
the  anaesthetic  side  a  partial  blindness  of  the  eye  {amblyopia 
or  7iemianopsia\  and  the  field  of  vision  for  color  is  remark- 
ably contracted,  as  first  pointed  out  by  Landolt. 

In  the  normal  eye  the  field  for  blue  is  the  largest ;  next 
comes  that  for  yellow  ;  then  orange,  red,  green,  and  violet 
have  fields  of  gradually  diminishing  size,  the  last  being  per- 
ceived only  by  the  most  central  parts  of  the  retina.  Now,  in 
connection  with  hemiansesthesia  caused  by  cerebral  lesions, 
the  perception  of  violet  first  disappears,  then  of  green,  and 
later  of  orange.     In  some  cases,  yellow  and  blue  can  be  per- 


198  THE  BR  Am, 

fectly  recognized ;  but  in  tlie  higher  degrees  of  anaesthesia  all 
colors  merge  into  a  uniform  sepia  tint.  Another  important 
fact  has  been  pointed  out  by  Landolt,  viz.,  that  the  eye  on 
the  same  side  as  the  lesion  participates,  though  to  a  less  ex- 
tent, in  the  loss  of  color-perception. 

Clinical  Deductions  drawn  from  Preceding  Pages. — 
Amblyopia  of  one  eye  can  result  from  lesions  involving  the 
optic  nerve  in  front  of  the  chiasm,  or  possibly  (?)  from  lesions 
of  the  internal  capsule.  If  from  the  latter,  the  field  for  color- 
perceptions  will  be  found  to  be  markedly  contracted  or  color- 
vision  will  be  wanting ;  both  eyes  may  be  affected,  the  most 
marked  changes  being  found,  however,  in  the  eye  opposite  to 
the  seat  of  the  lesion. 

Hemianopsia  may  occur  when  the  occipital  lobes  (chiefly 
the  cortex  of  the  cuneus),  Wernicke's  tract,  the  pulvinar  of 
the  thalamus,  the  optic  tracts,  or  the  optic  chiasm  are  pressed 
upon  or  destroyed  by  lesions  of,  or  in  the  region  of,  the 
cerebrum.  It  is  evident,  therefore,  that  the  trephine  cannot 
always  afford  relief  of  this  symptom.  When  syphilitic  gum- 
mata  may  be  suspected,  the  prognosis  is  extremely  favorable 
if  active  treatment  be  employed.  The  variety  of  hemianopsia 
often  indicates  the  seat  of  the  lesion  with  great  exactness. 

11  paralysis  (in  any  of  its  forms)  coexist  with  hemianopsia, 
a  valuable  guide  will  often  be  afforded  in  determining  the  ex^ 
tent  of  the  lesion. 

Crossed  paralysis  of  the  *'  olfactory  nerve  and  body  type  " 
indicates  a  localized  pressure  which  is  chiefly  exerted  upon 
parts  within  the  anterior  fossa  of  the  skull.  The  motor  tract 
is  probably  involved  by  upward  pressure  upon  the  caudate  or 
lenticular  nucleus,  or  the  fibers  of  the  internal  capsule,  thus 
accounting  for  the  hemiplegia  of  the  opposite  half  of  the  body. 
The  olfactory  nerve,  which  lies  near  to  the  optic  chiasm,  is 
affected  by  pressure  in  the  downward  direction,  and  the  optic 
chiasm  or  tract  may  be  simultaneously  involved  ;  hence  a  loss 
of  smell  in  the  nostril  on  the  same  side  as  the  lesion  may  co- 
exist with  some  form  of  hemianopsia,  as  well  as  with  a  crossed 
hemiplegia. 


CROSSED  PARALYSIS  AND   CHOKED  DISK.  199 

Crossed  paralysis  of  the  '' motor-oculi  nerve  and  body" 
type  indicates  a  lesion  situated  within  the  cms  cerebri.  If 
hemianopsia  be  present  in  connection  with  this  condition,  it 
proves  conclusively  that  the  optic  tract,  which  lies  in  close 
relation  with  the  crus,  is  simultaneously  affected  by  the  lesion. 
We  find,  therefore,  that  the  eye  on  the  same  side  as  the  lesion 
is  blind  in  its  temporal  half  if  the  optic  tract  be  involved ; 
that  it  can  no  longer  be  turned  toward  the  nose  or  made  to  act 
in  parallelism  with  the  opposite  eye  ;  that  the  pupil  is  dilated ; 
and  that  the  upper  eyelid  droops  over  the  eyeball,  giving  it  a 
sleepy  appearance.  On  the  side  opposite  to  the  lesion  the  eye 
is  blind  in  its  nasal  half,  and  the  body  is  hemiplegic.  There 
are  few  conditions  which  are  of  greater  clinical  importance 
than  this  type  of  crossed  paralysis,  because  the  seat  of  the 
lesion  is  i)ositively  indicated. 

ChoTced  disk  is  a  common  symptom  of  lesions  of  the  base 
of  the  cerebrum,  and  of  any  intra- cranial  disease  which  pro- 
duces a  gradually  increasing  pressure.  It  is  specially  diag- 
nostic of  tumors.  It  is  not  associated  w^ith  impairment  of 
vision  until  late,  so  that  it  is  often  unsuspected  when  present. 
The  ophthalmoscope  is  necessary  for  its  detection.  It  may 
coexist  with  hemianopsia,  and  is  always  bilateral.  It  is  a 
positive  contra-indication  to  trephining. 

Lesions  at  the  base  of  the  skull  may  cross  the  mesial  line, 
and  still  involve  only  one  optic  tract.  If  this  occurs,  the 
hemianopsia  will  be  accompanied  by  other  symptoms  of  diag- 
nostic importance,  no  longer  confined  to  one  side.  Double 
anosmia,  general  paresis  or  complete  paralysis,  general  anaes- 
thesia, and  paralytic  symptoms  referable  to  both  eyeballs, 
might  be  thus  produced.  Lesions  of  this  character  are  more 
liable  to  affect  the  chiasm  of  the  optic  nerves  than  the  optic 
tracts ;  in  either  case,  however,  hemianopsia  would  result, 
and  its  type  would  be  a  reliable  guide  to  the  seat  of  pressure 
(see  Fig.  43). 

Crossed  paralysis  of  the  ''facial  nerve  and  body  type"  is 
not  as  liable  to  coexist  with  hemianopsia  as  the  two  forms 
previously  mentioned.     The  reason  for  this  is  a  purely  ana- 


200  THE  BRAIN. 

tomical  one.  The  symptoms  of  facial  paralysis  are  too  in- 
volved to  be  given  here  in  detail. 

Uncomplicated  hemianopsia  indicates  that  no  pressure- 
effects  are  exerted  upon  the  motor  or  sensory  projection 
tracts,  or  adjacent  nerves. 

Aphasia  sometimes  coexists  with  hemianopsia.  I  have 
met  with  two  instances  of  this  kind.  In  one  there  was  slight 
paresis  of  the  left  side,  tending  to  prove  that  aphasia  can  oc- 
cur with  lesions  involving  the  right  hemisphere.  Both  were 
cured  with  specific  treatment.  We  must  attribute  the  devel- 
opment of  this  complication  to  pressure  upon  parts  in  the 
neighborhood  of  Broca's  center,  or  to  lesions  of  the  internal 
capsule,  where  the  speech  tract  comes  in  close  relation  to  the 
optic  fibers  (Fig.  39). 

Lesions  confined  to  the  crus  cerebri  seldom  create  impair- 
ment of  any  of  the  special  senses  excepting  that  of  the  sight. 
These  cases  are  not  associated  with  impairment  of  intellect  or 
usually  of  speech.  It  has  been  claimed  that  severe  lesions 
cause  paralysis  of  the  bladder,  but  I  have  never  encountered 
it.  Many  points  of  interest  pertaining  to  lesions  of  the  crura 
wiU  be  considered  later. 


THE    CRURA   CEREBRI. 

If,  after  the  removal  of  the  brain  from  the  skull,  the  base 
of  the  cerebrum  be  examined,  the  adjacent  parts  being  left 
intact  (Fig.  28),  it  will  be  perceived  that  the  crura  cerebri 
emerge  from  the  upper  border  of  the  pons  Varolii,  diverge 
from  one  another,  and  then  disappear  in  the  cerebral  hemi- 
spheres, passing  beneath  the  optic  tracts.  A  space  is  thus 
left  between  the  crura,  in  which  may  be  seen  the  so-called 
^'posterior  perforated  space''''  (where  the  vessels  enter  the 
brain  to  supply  the  optic  thalamus),  and  the  "corpora  mam- 
illaria"  (Fig.  37),  which  are  formed  by  the  anterior  pillars  of 
the  fornix.  ■ 

On  the  inner  aspect  of  each  crus,  near  to  the  angle  of 
divergence  from  its  fellow,  may  be  noticed  several  bundles  of 


h 


TEE  CEUS  CEREBRI. 


201 


fibers  which  issue  from  its  substance  to  form  the  third  cranial 
or  '' motor-oculi"  nerve  of  the  corresponding  side.  The 
groove,  from  which  these  bundles  escape,  may  be  considered 
as  an  external  indication  of  the  separation  of  the  fibers  con- 
tained within  the  crus  into  two  bundles  (the  '^  basis  cruris ^'^^ 
or  ^'cTUsta,^^  and  the  "tegmentum  cruris ^\  which  we  have 
already  discussed  (Fig.  45).  The  larger  portion  of  the  crus, 
which  lies  anterior  to  this  groove,  is  the  '^crusta"  ;  while  the 
*'  tegmentum  "  is  the  smaller  or  posterior  portion. 

If  a  cross-section  of  the  crus  be  now  made,  it  will  be  per- 
ceived (Fig.  45)  that  the  crusta  and  tegmentum  are  separated 
by  a  tract  of  dark-colored  gray  substance,  the  "'substantia 


Left  half,  designed  to  show  the  rela- 
tions of  certain  parts  to  one  another. 


Eight  half;  designed  to  show  the  two 
main  subdivisions  of  the  crus. 


(^Lateral 
(  qvoave 


Fig.  45. — A  diagrammatic  representation  hy  the  author  of  the  parts  seen  in  a  horizon- 
tal cross-section  on  a  level  with  the  snperior  quadrigeminal  body. 

c.  q.,  corpora  quadrigemina ;  S.  JV.,  substantia  nigra ;  R.  JV.,  red  nucleus ;  S.,  aqueduct 
of  Sylvius,  surrounded  by  its  gray  matter;  q.  t.,  tract  of  trigeminus  nerve  root 
(quintus  tract);  p.  If.,  posterior  longitudinal  fasciculus. 

nigra  "  of  Soemmering.  This  collection  of  nerve  cells  comes 
to  the  surface,  on  the  inner  aspect  of  the  cms,  at  a  point 
which  corresponds  to  the  escape  of  the  fasciculi  of  the  third 
cranial  nerve  (the  sulcus  oculo-motori\  and,   on  the  outer 


202  THE  BRAIN. 

aspect  of  the  crus,  along  a  grooved  line  (the  lateral  sulcus). 
The  construction  of  the  two  main  subdivisions  of  the  crus 
and  its  collections  of  gray  matter  must  be  considered  sepa- 
rately. 

The  Crusta  or  Basis  Cruris  {proper  cerebral  pedun- 
cle).— This  portion  of  the  cerebral  peduncle  lies  ventrad  of 
the  substantia  nigra,  and  is  formed  almost  entirely  of  bun- 
dles of  fibers  running  longitudinally,  and  continuous  below 
with  those  of  the  pons  Varolii  and  medulla  oblongata  (Fig. 
8).  It  is  semilunar  in  section — the  concave  surface  of  the 
substantia  nigra  projecting  into  it  (Fig.  45). 

Those  bundles  which  lie  adjacent  to  the  substantia  nigra 
are  smaller  than  the  rest  and  are  partially  separated  by  pro- 
cesses of  this  gray  mass  (left  half  of  Fig.  45).  They  have 
been  named  by  Meynert  the  ''stratum  intermedium.^^  Their 
origin  and  termination  differ  from  those  of  the  bundles  which 
lie  more  anteriorly.  They  serve  to  connect  chiefly  the  cells 
of  the  substantia  nigra  with  the  reticular  formation  of  the 
pons  and  medulla,  although  a  few  pass  upward  to  join  the 
lenticular  nucleus  (Meynert). 

The  main  tracts  of  the  crusta  are  a  direct  prolongation 
downward  of  fibers  of  the  internal  capsule  of  the  cerebrum 
(Fig.  8)  and  corona  radiata.  These  fibers  are  continuous 
below  with  those  of  the  anterior  pyramids  of  the  medulla 
oblongata,  at  the  lower  part  of  which  ganglion  the  majority 
of  the  bundles  decussate  and  pass  down  the  lateral  columns 
of  the  opposite  side  of  the  spinal  cord  as  the  ''crossed 
pyramidal  tracts''''  (Fig.  46).  The  ganglia  of  origin  are  pos- 
sibly the  nucleus  caudatus  and  the  nucleus  lenticularis,  but 
more  probably  the  cells  of  the  motor  cerebral  gyri. 

The  bundles  which  are  situated  in  the  lateral  or  outer 
part  of  the  crusta  are  stated  by  Meynert  to  present  peculiari- 
ties of  origin  and  distribution.  He  believes  that  the  fibers 
which  compose  these  bundles  arise  from  the  occipital,  parietal, 
and  temporo-sphenoidal  lobes  of  the  cerebrum  (the  sensory 
area\  and  enter  the  crus  without  any  apparent  connection 
with  the  cells  of  the  basal  ganglia  ;  that  they  decussate  in  the 


MOTOR  FIBERS  OF  CRUSTA    CRURIS. 


203 


Pyramidal  fibers  of   the 
left  cerebral  hemisphere. 


Fibers  of  Tiirck'B  col 
umn  of  left  half 
cord. 

Fibers  of  the  crossed 
pyramidal  column  of 
the  left  side  of  cord. 


.'  y — [Pyramidal  fibers  of  the  right  cere- 
\^f3  t,    bral  hemisphere. 


{Decnssatlon  of  the  crossed  pyra- 
midal tracts  within  the  me- 
dulla oblontrata. 


Fibers  of  Turck's  column  of 
right  half  of  cord. 

r  Fiber  of  the  crossed  pyra- 
"S  midal  column  of  the  right 
^    side  of  cord. 


Column  of  Tiirck  of  right 
Bide. 


../Direct  cerebellar  col- 

\    umn  of  right  side. 
...f  Crossed      pyramidal 

t    column     of    right 
Bide.  ^ 


Fig.  46. — A  diagram  designed  hy  the  author  to  show  the  course  of  the  fibers  of  the 
crusta  cerebri  {motor)  after  they  leave  the  pyramids  of  the  medulla. 

The  direct  pyramidal  tracts  {a-a,  b-b)  pass  down  the  column  of  Tiirck  (T^'s  Col.)  of  the 
same  side  of  the  cord.  The  crossed  pyramidal  tracts  (c-c,  d-d)  pass  down  the  so- 
called  crossed  pyramidal  column  (C.  P.  C.)  of  the  opposite  side  of  the  cord ;  £^s  C, 
Burdach's  column ;  Cs  C,  Goll's  column ;  D.  C.  C,  direct  cerebellar  column. 


204 .  THE  BRAIK 

medulla,  above  the  point  of  crossing  of  the  lateral  pyramidal 
fasciculus  just  described ;  and,  finally,  that  they  can  be  traced 
to  the  posterior  column  of  the  opposite  side  of  the  spinal 
cord. 

Flechsig  has  shown  that  the  bundles  of  the  crusta  lying 
nearest  to  the  mesial  plane  of  the  body  are  developed  later 
than  those  of  the  main  pyramidal  tracts,  and  are  therefore  to 
be  considered  as  a  distinct  formation. 

Finally,  there  remain  to  be  added  to  the  four  sets  of  fibers 
already  described  certain  bundles  which  are  connected  with 
the  cerebellum  and  which  interlace  themselves  with  the  fibers 
of  the  cerebral  tracts— chiefly  during  their  passage  through    .\ 
the  pons  Varolii.  ■■  H 

In  summary,  it  may  be  said  that  the  crusta  is  composed  of 
five  sets  of  bundles,  each  of  which  has  probably  a  function     ' 
of  its  own,  and  certain  individual  peculiarities  of  distribution 
which  distinguish  it  from  the  others. 

I  have  not  mentioned  among  these  five  distinct  tracts  of  j 
the  crusta  the  fibers  of  the  third  cranial  nerve  which  are  j 
depicted  in  the  diagram  (Fig.  45).  The  motor-oculi  fibers  ; 
escape  from  the  crus  in  the  region  of  the  substantia  nigra,  ; 
and  are,  therefore,  not  associated  with  those  bundles  which  lie  : 
anteriorly  to  it.  \ 

The  ganglia  of  origin  of  the  fibers  which  help  to  compose  \ 
the  crusta  are  believed  to  be  as  follows:  (1),  The  nucleus  \ 
caudatus ;  (2),  the  nucleus  lenticularis  ;  (3),  the  substantia  \ 
nigra;  (4),  the  motor  cerebral  convolutions;  (5),  possibly  i 
some  parts  of  the  sensory  area  of  the  cerebral  cortex.  The  ] 
first  and  second,  as  well  as  the  fourth  and  fifth,  have  already  \ 
been  described  as  parts  of  the  so-called  "corpus  striatum,"  < 
and  the  fibers  of  the  crusta  which  are  anatomically  related  to  ; 
them  have  received  more  or  less  notice  in  previous  pages.  It  : 
is  necessary,  therefore,  to  confine  our  remarks  here  only  to  i 
the  third  of  these  ganglionic  masses.  ©! 

The  Substantia  Nigra  {locus  niger).— This  collection  ofe^l 
gray  matter  separates  the  fibers  of  the  crusta  from  those  of  the  < 
tegmentum  cruris  (Fig.  45).     Its  limits  extend  vertically  from 


THE  SUBSTANTIA  NIGRA.  205 

the  posterior  border  of  the  corpora  albicantia  to  the  upper 
border  of  the  pons  Varolii.  The  nerve  cells  which  compose  it 
are  darkly  pigmented.  This  gives  it  the  appearance  indicated 
by  its  name.  It  is  thicker  in  its  mesial  portion  than  laterally, 
and  sends  out  processes  which  penetrate  between  the  longi- 
tudinal bundles  which  form  the  crusta.  One  very  marked 
projection,  in  which  the  nerve  cells  are  smaller  and  more 
numerous  than  else  were,  marks  the  dividing  line  between  the 
inner  and  middle  thirds  of  the  crusta. 

At  its  inner  border,  the  substantia  nigra  is  traversed  by 
the  fibers  of '  origin  of  the  third  cranial  or  motor-oculi  nerve 
(Fig.  45).  Some  of  these  fibers  also  pass  through  its  inner 
third. 

The  cells  of  the  substantia  nigra  are  supposed  to  afford  a 
communication  between  fibers  of  the  cerebrum  and  some  bun- 
dles of  the  cerebellar  system  of  fibers.  Certain  spinal  fibers 
also  terminate  within  them,  according  to  Meynert  and  others. 
When  we  consider  how  marvelous  it  is  that  the  muscular  ap- 
paratus can  act  in  perfect  harmony  with  the  impressions 
which  we  are  constantly  receiving  by  means  of  sight,  hear- 
ing, and  the  tactile  sense,  as  exhibited  in  the  finer  feats  of 
balancing,  dancing,  etc.,  it  becomes  evident  that  the  nerves 
which  carry  such  sensory  impressions  to  the  nerve  centers 
must  be  brought  somewhere  into  a  close  relationship  with 
the  motor  nerves  which  influence  the  muscles  of  the  ex- 
tremities. It  has  been  already  shown  that  an  animal  de- 
prived of  the  cerebral  hemispheres  (but  not  of  the  basal 
ganglia)  can  perform  feats  of  equilibrium  with  perfect  exact- 
ness. It  is  manifest,  therefore,  that  we  must  look  to  the 
basal  ganglia  of  the  cerebrum,  or  to  parts  associated  with 
them  (chiefly  the  cerebellum),  as  the  probable  seat  of  these 
coordinated  movements.  To  what  extent  the  cells  of  the  sub- 
stantia nigra  enter  into  this  complicated  mechanism  is  as  yet 
problematical,  but  there  is  little  doubt  that  it  constitutes  one 
of  its  important  factors. 

The  Tegmentum  Cruris.— The  fibers  of  the  posterior  di- 
vision of  the  crus  cerebri  (Fig.  45)  have  the  following  ganglia 
IG 


206  THE  BRAIK 

of  origin :  (1),  The  optic  thalami ;  (2),  the  corpora  quadri- 
gemina ;  (3),  the  corpora  geniculata ;  (4),  the  corpora  mam- 
illaria ;  (5),  the  ansa  peduncularis ;  (6),  the  pineal  gland; 
(7),  the  red  nucleus  ;  (8),  the  ganglion  of  the  hahenula. 

Most  of  these  have  been  already  considered.  The  re- 
mainder will  be  described  in  connection  with  the  fibers  which 
arise  from  them. 

The  tegmentum  is  composed  of  small  longitudinal  bundles 
of  nerve  fibers,  more  or  less  extensively  interlaced  by  others 
which  are  directed  transversely.'    The  bundles  are  also  sepa- 

*  The  distinct  nerve  tracts  within  the  tegmentum  cruris  have  been  lately  observed  by 
Flechsig,  with  a  view  of  determining  the  relative  periods  of  development  of  each,  and  thus 
positively  determining  their  course  and  probable  functions  with  some  approach  to  ac- 
curacy.    It  may  be  well  to  summarize  the  results  of  these  investigations,  as  follows : 

1.  The  mperior  peduncle  of  the  cereJcWwm  ("  processus  e  cerebello  ad  testes  "of  the 
earlier  anatomists)  was  found  to  arise  (1)  from  the  dentate  nucleus,  and  (2)  from  the 
cerebellar  cortex  near  to  the  worm.  By  the  first  point  of  origin,  it  is  brought  indirectly  into 
intimate  relationship  with  the  restiform  tracts  of  the  cord  and  some  parts  of  the  cere- 
bellar cortex.  Some  of  its  fibers  appear  to  terminate  in  the  red  nucleus  of  the  opposite 
side.  The  remaining  bundles  terminate,  according  to  this  author,  in  the  lenticular  nucleus 
and  the  corona  radiata. 

2.  The  lemniscus  seems  to  consist  of  two  distinct  sets  of  fibers  ;  one  of  which  under- 
goes descending  degeneration,  and  the  other  ascending  degeneration  when  separated  from 
their  trophic  centers.  We  can,  therefore,  conclude  that  they  carry  impulses  that  corre- 
spond to  the  form  of  degeneration  that  they  undergo,  one  centrifugal  and  the  other  cen- 
tripetal. The  centrifugal  conducting  tract  comprises  two  thirds  of  the  entire  bulk  of  the 
lemniscus.  It  arises  from  the  external  division  of  the  lenticular  nucleus  of  the  corpus 
striatum  and  takes  the  following  course  from  above  downward :  (1)  across  the  internal 
capsule  ;  (2)  above  the  body  of  Luys ;  (3)  to  the  outer  side  of  the  red  nucleus  ;  (4)  through 
the  substance  of  the  pons,  lying  dorsal  of  the  pyramidal  tracts  ;  (5)  it  terminates  in  the 
olivary  body.  The  centripetal  conducting  tract  arises  at  the  sensory  decussation  of  the 
medulla  and  then  passes  through  the  pons  and  afterward  behind  the  red  nucleus  of  the 
tegmentum.  It  then  turns  beneath  the  corpus  quadrigeminum  inferior  and  the  pulvinar, 
and  becomes  lost  in  the  corona  radiata. 

3.  T\\Q  posterior  longitudinal  fascicidibs.  This  bundle  seems  to  be  composed  of  fibers 
of  association  between  the  nuclei  of  origin  of  the  cranial  nerve  roots,  chiefly  those  of  the 
third,  fourth,  and  sixth  nerves.  It  can  be  shown  to  be  connected,  below,  with  the  ante- 
rior columns  of  the  cord,  thus  demonstrating  that  it  is  physiologically  related  to  motion. 
Superiorly,  it  is  continued  into  the  gray  lining  of  the  third  ventricle.  This  tract  is  the 
first  to  be  developed  in  the  brain  of  the  foetus.  It  lies  immediately  beneath  the  gray 
lining  of  the  fourth  ventricle. 

4.  The  formatio  reticularis.  The  fibers  that  become  intermingled  in  this  structure 
are  not  yet  definitely  settled.  Flechsig's  researches  seem  to  establish  the  presence  of 
fibers  that  descend  from  the  quadrigeminal  bodies,  as  well  as  some  that  ascend  from  the 
posterior  columns  of  the  cord. 

5.  The  general  sensory  tract  from  the  periphery  to  the  cerebral  cortex  seems  to  be 
formed  above  the  medulla  by  the  union  of  fibers  derived  from  the  superior  peduncle  of  the 


i 


FIBERS  OF  THE  TEGMENTUM  CRURIS.  207 

rated  to  some  extent  by  collections  of  gray  matter  contain- 
ing scattered  nerve  cells.  Some  of  the  bundles  form  well- 
defined  tracts.     These  will  demand  a  separate  description. 

The  Posterior  Longitudinal  Bundle.— This  tract  of  fibers 
(Fig.  45)  lies  between  the  gray  matter  underlying  the  aque- 
duct of  Sylvius  and  the  so-called  ''reticular  formation,-'  so 
well  defined  in  transverse  sections  made  through  the  upper 
part  of  the  pons  Varolii.  If  traced  upward,  the  fibers  which 
compose  this  bundle  seem  to  become  lost  in  the  region  of  the 
posterior  commissure,  either  by  becoming  intermingled  with 
the  nuclei  of  origin  of  the  third  and  fourth  cranial  nerves 
in  the  mesencephalon,  or  by  a  dispersion  in  the  reticular 
formation.  Below,  they  appear  to  be  a  continuation  of  the 
fibers  of  the  anterior  column  of  the  spinal  cord.  It  will  be 
again  referred  to  when  the  architecture  of  the  medulla  oblon- 
gata is  considered. 

The  Superior  Peduncle  of  the  Cerebellum. — This  tract  will 
be  discussed  in  detail  in  connection  with  the  description  of 
the  cerebellum.  It  has  been  already  referred  to  when  the 
caudate  nucleus  of  the  corpus  striatum  was  under  considera- 
tion. It  bears  an  intimate  relation  after  decussation  with  the 
red  nucleus  of  the  tegmentum  (Fig.  45),  from  the  cells  of 
which  some  accessory  fibers  are  probably  given  to  it.  The 
decussation  of  the  fibers  of  this  tract  can  easily  be  demon- 
strated in  all  cross- sections.  It  is  claimed  by  Luys  that  this 
bundle  of  fibers  enables  the  cerebellum  to  reenforce  the  cells 
of  the  corpus  striatum.  Some  anatomists  claim  that  the  optic 
thalamus  receives  some  of  its  fibers.  Flechsig  traces  its  fibers 
to  the  lenticular  nucleus  and  the  corona  radiata. 

The  Tract  of  the  Fillet  {Lemniscus  Tract).— TYas  tract  has 
been  the  subject  of  much  investigation.     At  the  upper  level 

cerebellura,  the  sensory  division  of  the  lemniscus,  the  ascending  fibers  of  the  formatio 
reticularis,  and  a  few  fibers  of  the  posterior  longitudinal  bundle.  These  tracts  unite  at 
about  the  level  of  the  quadrigeminal  bodies.  They  then  become  joined  by  fibers  arisinir 
from  these  bodies  and  pass  into  the  posterior  part  of  the  internal  capsule,  and  radiate, 
opposite  the  posterior  third  of  the  thalamus,  into  the  cortex  of  the  parietal  and  temporal 
regions  and  the  precuneus.  The  term  "  corona  of  the  tegmentum "  is  applied  to  the 
tract  as  a  whole. 


208  THE  BRAIN. 

of  the  pons  it  appears  as  a  flattened  bundle  of  longitudinal 
fibers  at  the  anterior  border  of  the  reticular  formation  (Fig. 
45).  It  is  prolonged  cephalad  into  the  corresponding  part  of 
the  tegmentum.  Some  of  its  fibers  pass  obliquely  outward, 
and  curve  over  the  cerebellar  peduncle  at  the  side  of  the  cms. 
In  the  latter  respect,  they  resemble  the  course  of  the  anterior 
medullary  velum^  whose  fibers  reenforce  those  of  the  fillet. 
A  layer  of  gray  matter  covers  the  fillet  externally.  The  fibers 
of  this  tract  are  thought  by  some  anatomists  to  be  chiefly  dis- 
tributed, above,  to  the  inferior  quadrigeminal  body.  Below, 
they  appear  to  be  connected  with  the  nuclei  of  the  posterior 
columns  of  the  spinal  cord.  Some  of  its  fibers  probably  be- 
long to  the  sensory  tracts  of  the  cord.  The  name  'lemniscus " 
is  applied  to  the  curved  fibers  of  the  fillet. 

The  views  of  Flechsig  respecting  the  composition  of  the 
fillet  have  been  given  in  a  foot-note  on  a  preceding  page. 

The  mesial  fibers  of  the  tract  of  the  fillet  are  believed  by 
Meynert  to  j)ass  upward  in  the  intermediate  stratum  of  the 
crusta. 

According  to  the  researches  of  Forel,  a  middle  portion  of 
this  tract  presents  some  peculiarities  of  course  and  distribu- 
tion. Some  pass,  according  to  this  author,  upward  through  the 
reticular  formation,  and  subsequently  join  the  corpus  albicans 
or  become  lost  in  the  longitudinal  bundles ;  a  few  of  the 
lateral  fibers  of  this  middle  portion  pass  to  the  upper  quadri- 
geminal body  {natis  cerehri\  this  bundle  being  distinguished 
as  the  ''  upper  fillet  ^^  m  contradistinction  from  the  fibers  of 
the  lateral  portion  of  the  tract  which  pass  to  the  lower  quad- 
rigeminal body  {testis  cerebri\  which  are  known  as  the  ''''lower 
fillet:' 

Some  authorities  claim  that  the  fibers  of  the  tract  of  the 
fillet  may  be  traced  into  the  posterior  part  of  the  lateral 
column  of  the  spinal  cord,  as  well  as  into  the  anterior  column. 

Late  researches,  regarding  the  physiological  function  of 
this  tract  of  fibers,  seem  to  point  toward  a  relationship  be- 
tween the  lemniscus  and  the  so-called  "muscular  sense" 
(Spitzka  and  Starr). 


THE  LEMNISCUS,    OR  FILLET  TRACT.  209 

The  fillet  tract  becomes  intermingled  with  the  fibers  of  the 
stratum  intermedium,  although  it  lies  more  to  the  lateral  por- 
tion of  the  medulla.  It  is  apparently  connected  above  with 
the  inferior  corpora  quadrigemina  (testes  cerebri),  although 
some  observers  think  its  fibers  pass  to  the  cerebral  cortex  by 
means  of  the  corona  radiata ;  below,  it  is  believed  to  partici- 
pate to  some  extent  in  the  piniform  decussation  (Spitzka). 
Some  authors  are  led  to  believe  that  this  tract  is  intimately 
associated  with  the  sense  of  sight  as  well  as  with  coordination 
of  movements. 

E.  C.  Spitzka  has  lately  investigated  the  results  of  a  lesion 
of  the  pons  that  chiefly  involved  the  fillet  tract.  The  case  is 
one  of  great  interest,  as  bearing  upon  the  question  of  the 
probable  paths  of  coordination.  The  prominent  symptom 
during  the  life  of  the  patient  was  an  inability  to  perform  co- 
ordinated movements  upon  the  right  side. 

The  deductions  drawn  by  this  observer,  from  a  careful 
study  of  microscopical  sections  of  the  pons  and  medulla,  are 
summarized  by  him  as  follows  ("New  York  Medical  Journal," 
March  15,  1884) : 

*^  1.  The  so-called  lemniscus  layer  contains  in  its  mesal  por- 
tion an  individualized  column  of  fibers  of  high  physiological  im- 
portance, which  decussates  in  the  so-called  sensory  decussation  of 
Meynert. 

'*  2.  The  stratum  intermedium,  as  this  bundle  should  be  called, 
for  reasons  to  be  advanced  further  on,  is  a  tract  mediating  an  essential 
factor  of  voluntary  motility — coordination. 

**  3.  The  ataxia  of  movement  observed  in  destruction  of  this  tract 
is  not  due  to  a  loss  of  tactile  sensibility.  The  latter  was  not  sufficiently 
impaired  to  account  for  the  absolute  unilateral  ataxia  attributable  to 
the  division  of  the  stratum  intermedium. 

*^4.  The  stratum  intermedium  is  not  purely  a  centripetal  tract. 
It  degenerates  centrifut^ally. 

"  5.  Physiologically,  it  appears  to  be,  in  part  at  least,  centripetal ; 
this  is  shown  by  the  paraesthesia  and  hypersesthesia  complained  of  by 
the  patient. 

"  6.  While  the  stratum  intermedium  is  probably  the  continuation 
Oi  the  column  of  Goll,  and,  in  part,  of  that  of  Burdach,  toward  the 
cerebrum,  the  secondary  degeneration  of  the  spinal  part  of  this  (ideal) 
tract  advances  centripetally,  while  the  cerebral  portion  degenerates 


210  THE  BRAIK 

centrifugally,  the  point  to  which  both  converge  being  the  nuclei  of 
the  posterior  columns. 

**  7.  Flechsig's  statement  that  there  is  no  direct  continuation  of 
the  posterior  columns  into  the  piniforra  decussation,  but  that  they 
terminate  provisionally  in  their  nuclei,  is  demonstrated  beyond  perad- 
venture  by  this  case. 

"  8.  While  Flechsig  is  also  sustained  in  his  denial  of  a  gross  con- 
nection between  the  so-called  upper  pyramidal  decussation  of  Meynert 
and  the  pyramids  proper,  yet  there  is  an  intimate  connection  between 
the  stratum  intermedium  and  the  pyramid  of  the  same  side,  extending 
along  the  known  course  of  the  former  tract  from  its  decussation  up  to 
the  lower  part  of  the  pons.  It  is  possible  that  the  connection  between 
the  sensory  periphery  and  the  pyramids,  which  Meynert  attempted  to 
establish,  really  exists  through  the  medium  of  this  interchange,  though 
in  much  lesser  degree  than  the  distinguished  founder  of  modern  cere- 
bral anatomy  surmised. 

"  9.  The  system  of  fibers  which  is  represented  in  the  fasciculi  arch- 
ing through  the  olivary  nuclei,  those  of  the  external  arciform  group 
— and  which  are  not  without  reason  supposed  to  connect  the  posterior 
columns,  or  rather  the  latter,  through  nuclear  intervention,  with  the 
restiform  column — is  entirely  independent  of  the  stratum  intermedium. 
Nor  have  the  olivary  nuclei,  or  any  of  the  tracts  connected  with  them, 
a  connection  with  the  stratum  intermedium. 

"  10.  The  vertical  fibers  of  the  trapezium  appertain  to  the  stratum 
intermedium." 

The  results  of  Starr's  investigation  of  a  microcephalic  brain 
(lately  awarded  the  Alumni  Association  prize  of  the  College 
of  Physicians  and  Surgeons)  are  not  in  full  accord  with 
Spitzka  regarding  this  tract. 

Ganglia  of  the  Tegmentum. — That  there  is  a  functional 
independence  between  the  cerebral  hemispheres  and  the 
masses  of  gray  matter  connected  with  the  fibers  of  the  pos- 
terior division  of  the  crus  seems  to  be  proved  by  a  comparison 
of  the  relative  development  of  the  two  in  animals.  The  optic 
thalami  and  corpora  quadrigemina  are  less  developed,  in  pro- 
portion to  the  weight  of  the  cerebrum,  in  man  than  in  either 
the  ape  or  deer. 

The  OPTIC  THALAMUS  is  probably  associated  with  the  fibers 
of  the  tegmentum  (1)  by  means  of  the  bundle  connected  with 
the  ganglion  of  the  hahenula  conarii ;  (2)  by  means  of  the 
so-called  lamince  medullar es  ;  (3)  by  means  of  the  posterior 


J  J 


GANGLIA    OF  TEE  TEGMENTUM  CRURIS.  211 

commissure.  Differences  of  opinion  exist  between  Meynert 
and  Luys  respecting  the  relations  of  special  fibers  to  the 
ganglionic  masses  found  within  the  thalamus.  Some  of  these 
have  been  already  discussed.  Future  investigations  regard- 
ing the  effects  of  disease  of  these  parts  and  additional  light 
afforded  by  experimental  physiology  can  alone  render  our 
knowledge  of  the  sensory  tracts  of  the  brain  less  conjectural. 
The  latest  conclusions  of  Flechsig,  Spitzka,  and  Starr  are  of 
particular  interest  in  this  connection. 

The  anterior  coepus  quadrigeminum  of  either  side  seems 
to  be  associated  with  the  special  sense  of  sight,  although  its 
connections,  as  well  as  those  of  the  posterior  pair,  with  the 
fibers  of  the  tegmentum  and  the  cerebellum  would  indicate  a 
more  extended  function.  In  previous  pages,  the  structure  of 
this  ganglion  (taken  as  a  whole)  and  the  results  of  physio- 
logical experiments  upon  it  have  been  discussed  in  detail. 
Setschenow  has  shown  that,  among  the  other  functions  which 
this  ganglion  seems  to  possess,  it  appears  to  be  able  to  inten- 
sify the  inhihitory  or  controlling  influence  of  the  brain  upon 
the  reflex  actions  of  the  spinal  cord.  Although  it  is  unques- 
tionably connected  with  the  optic  fibers,  this  ganglion  is  cer- 
tainly not  the  center  of  consciousness  of  visual  impressions. 
It  seems  probable  rather  that  it  may  be  a  center  of  coordina- 
tion between  retinal  impressions  and  special  muscular  move- 
ments. It  is  stated  by  some  observers  that  blindness  of  the 
opposite  eye  follows  its  destruction,  but  this  is  not  accepted 
as  proved  by  all  physiologists. 

Impairment  of  sight  may  be  attributed  in  many  cases  to  a 
severance  of  the  optic  fibers  from  their  connections  with  the 
visual  area  of  the  convolutions.  Such  an  occurrence  in  con- 
nection with  a  lesion  of  the  anterior  pair  does  not  prove  that 
the  corpora  quadrigemina  are  centers  of  vision.  They  stand 
in  no  constant  relation  to  the  development  of  the  eyes,  as  is 
proved  by  the  fact  that  they  are  largely  developed  in  some 
animals  where  the  eyes  and  optic  tracts  are  rudimentary 
(Longet). 

Goltz,  Serres,  Cayrade,  and  others  have  noticed  effects, 


212  THE  BRAIK 

produced  by  destruction  of  these  bodies,  upon  the  function 
of  equilibration,  Ferrier  has  confirmed  these  statements  by- 
experiments  made  upon  monkeys,  fishes,  and  rabbits,  and 
McKendrick  has  been  led  to  the  same  conclusion  by  his  in- 
vestigations upon  pigeons. 

Goltz  and  Vulpian  were  led  to  believe  that  plaintive  cries 
(as  a  form  of  emotional  expression  produced  by  sensations  of 
pain  or  pleasure)  ceased  when  the  corpora  quadrigemina  were 
destroyed.  Ferrier  thinks  that  this  conclusion  is  only  partly 
true ;  because  he  was  able  by  intense  stimulation  to  excite 
responses  in>  the  form  of  cries  in  a  rabbit  whose  optic  lobes 
had  been  entirely  removed. 

Spitzka  employs  the  following  diagram  to  interpret  his 
views  respecting  a  supposed  relationship  between  the  inferior 
quadrigeminal  bodies  (post-optic  lobes)  and  visceral  and  vaso- 
motor innervations  (page  213). 

The  effects  observed  in  the  pupillary  movements  and  oculo- 
motor reactions  after  mechanical  irritation  and  electric  stimu- 
lation of  these  bodies  in  animals  are  comparatively  uniform. 
The  pupils  dilate,  the  head  and  eyes  are  turned  to  the  opposite 
side,  the  ears  are  drawn  backward,  the  jaws  become  clinched 
firmly,  the  lips  are  retracted,  and  finally  complete  opisthoto- 
nos is  produced.  Various  forms  of  vocalization  have  also 
been  observed  to  follow  irritation  of  the  "  testes  cerebri."  It 
is  impossible  to  state  which  of  these  effects  is  due  to  irrita- 
tion of  the  optic  lobes  themselves  and  which  to  the  tracts  of 
fibers  underlying  them.  The  ganglia  of  the  mesencephalon  as 
well  as  the  cerebellum  are  too  intimately  connected  with  the 
pons  and  crura  to  make  any  positive  differentiations  possible. 

Meynert's  view  that  one  of  the  roots  of  the  fifth  nerve 
can  be  traced  to  a  collection  of  large  cells  w^hich  lies  adjacent 
to  the  aqueduct  of  Sylvius  may  help  to  interpret  the  move-  \ 
ments  of  the  jaws  when  the  optic  lobes  are  stimulated.  We  ? 
meet  with  similar  manifestations  of  transmitted  irritation  by 
means  of  the  spinal  cord  in  tetanus  ;  and,  when  these  phenom- 
ena are  grouped  with  the  movements  of  the  limbs  and  trunk  ; 
which  are  likewise  created  by  excitation  of  the  corpora  quad- 


CONNECTION'S  OF  POST-OPTIC  GANGLION 


213 


rigemina  in  frogs,  fishes,  and  mammals,  we  are  forced  to  the 
conviction  that  these  ganglia  are  important  factors  in  the  ex- 
hibition of  the  physical  emdences  of  painful  sensations  in 
general. 


POST.  OPTIC 
GANGLION. 


POST.  OPTIC 

GAN 

GLION. 

_I     . 

IX  PAIR. 

<  2 

Z  ^ 

>  1- 

si 

Si  Q 
1  ^ 

X  PAIR. 

i  X 

y 

5i 

_XI_PAIR. 

^1 

3o 

z  g 

\ 

»- 

u. 

POSTERIOR  COLUMNS 
OF  SPINAL  CORD. 


Spttzka's  Diagram. 


Danilewsky  finds  that  modifications  in  the  arterial  press- 
ure^ associated  with  a  slowing  of  the  heart  and  amplification 
of  the  pulse-waives^  follows  electric  stimulation  of  these  gan- 
glia, and  Budge  and  Valentin  claim  to  have  created  contrac- 
tions of  the  stomachy  intestine^  and  bladder  in  the  same  man- 
ner. I  am  inclined  to  doubt,  however,  if  these  phenomena 
are  due  to  the  local  effects  of  such  stimulation,  because  we 


214  THE  BRAIN. 

know  positively  that  electric  currents  are  often  widely  dif- 
fused. They  have  been  adduced,  however,  by  Ferrier  as 
proofs  (not  well  established)  of  the  relation  of  the  optic  lobes 
to  the  reflex  manifestations  of  emotion.  Fear  is  not  uncom- 
monly exhibited,  as  we  know,  by  the  human  race  as  well  as 
by  some  animals,  by  involuntary  passage  of  the  urine  and 
faeces,  and  occasionally  by  vomiting. 

The  relation  of  the  corpora  quadrigemina  to  vision,  as  well 
as  some  other  pathological  and  physiological  facts  of  clinical 
interest,  has  been  considered  more  fully  in  previous  pages,  to 
which  the  reader  is  referred. 

The  Geniculate  Bodies. — These  ganglia  (Fig.  43)  are 
considered  by  some  authors  as  appendages  to  the  optic  thai- 
ami  and  the  corpora  quadrigemina,  because  they  appear  to 
be  associated  to  a  greater  or  less  extent  with  the  special  sense 
of  sight.  Their  situation  furthermore  supports  the  view  of 
Meynert,  that  they  are  also  ganglia  of  origin  of  fibers  of  the 
tegmentum. 

In  the  external  geniculate  body  the  gray  matter  is  ar- 
ranged in  laminse  which  present,  in  cross-sections  made 
through  its  substance,  a  zigzag  outline,  as  if  the  laminae  had 
been  crushed  or  folded  together.  The  cells  of  tl^is  mass  are 
large,  granular,  and  pigmented. 

The  internal  geniculate  body  is  less  intimately  connected 
with  the  optic  lobes  and  the  fibers  of  the  optic  tract,  as  proved 
by  the  latest  researches  of  Flechsig,  Gudden,  and  Ganser. 
Its  gray  matter  is  not  arranged  in  the  manner  peculiar  to  its 
companion,  although  it  is  apparently  traversed  by  fibers  of 
the  optic  tract  connected  with  both  the  natis  and  testis  cere- 
bri. The  nerve  cells  of  this  body  appear  to  effect  a  decided 
reduction  in  the  number  of  fibers  which  pass  through  it. 

Some  of  the  optic  fibers  pass  directly  from  the  optic  tract 
to  the  corpora  quadrigeminum  without  any  intervention  of 
these  ganglionic  bodies,  while  a  few  of  the  innermost  bundles 
of  the  optic  tract  become  apparently  intertwined  with  the 
outermost  fasciculi  of  the  crusta.  Burdach  thinks  that  he 
has  traced  a  connection  between  these  bundles  and  the  sub- 


BED  NUCLEUS  AND  PINEAL   GLAND,  215 

stantia  nigra  of  Soemmering.  Meynert  has  not  been  able  to 
confirm  this  view. 

The  Red  Nucleus  of  the  Tegmentum. — This  ganglionic 
mass  has  been  discussed  already  in  connection  with  the  supe- 
rior peduncle  of  the  cerebellum,  and  will  be  again  referred  to 
when  the  cerebellum  is  described.     It  is  shown  in  Fig.  43. 

The  Mammillaky  Tubercle  {corpus  albicans — bulb  of  the 
fornix). — The  situation  of  this  body,  as  well  as  its  method  of 
formation,  is  shown  in  a  preceding  diagram  (Fig.  37).  Its 
structure  has  been  discussed  in  connection  with  the  third 
ventricle.  It  is  classed  by  Meynert  and  others  among  the 
ganglia  of  origin  of  the  tegmental  fibers. 

The  Pineal  Gland. — This  body  (the  conarium\  which 
resembles  a  fir-cone  in  shape,  lies  above  and  between  the  two 
upper  quadrigeminal  bodies  (Fig.  37).  It  is  often  spoken  of 
as  the  ^'JiypopJiysis  cerebri^^'*  although  improperly  so  accord- 
ing to  the  view  of  Meynert.  The  opinion  of  Luys  that  this 
body  is  directly  continuous  with  the  gray  lining  of  the  third 
ventricle  is  opposed  by  Arnold,  who  claims  to  have  demon- 
strated that  it  is  separated  from  it  by  a  medullary  layer. 
Meynert  regards  it  as  one  of  the  ganglia  of  origin  of  the  teg- 
mentum cruris,  since  it  is  connected  with  the  crus  by  means 
of  the  posterior  commissure.  It  is  also  connected  with  the 
meduUary  substance  of  the  cerebral  hemispheres  by  means 
of  its  peduncles. 

The  cells  which  are  found  within  the  gray  substance  of  the 
pineal  gland  are  of  two  sizes,  one  15 /^  and  the  other  6/i  in 
thickness.  These  cells  are  packed  more  closely  than  in  the 
other  cerebral  ganglia. 

The  pedicle  of  the  pineal  gland  {Jiabenula)  is  believed  by 
Meynert  to  be  directly  connected  with  the  posterior  com- 
missure of  the  third  ventricle,  as  well  as  with  the  fornix 
anteriorly. 

In  microscopic  structure  the  pineal  gland  bears  a  resem- 
blance to  the  anterior  lobe  of  the  pituitary  body.  A  number 
of  hollow  follicles  may  be  demonstrated  within  it,  which  are 
filled  with  epithelial  cells,  and  a  gritty  matter— the  so-called 


216  THE  BRAIK 

acervulus  cerebri  or  brain-sand.     This  sabulous  material  is 
also  found  upon  the  exterior  of  the  gland  and  its  peduncles. 

During  the  development  of  the  brain  the  pineal  gland  ap- 
pears as  a  hollow  excrescence  from  the  part  destined  to  form 
the  third  ventricle.  Subsequently,  this  diverticulum  becomes 
cut  off  from  the  ventricle,  and  tubes  develop  within  it.  Final- 
ly, these  tubes  are  seen  to  separate  into  isolated  vesicles,  which 
are,  as  a  rule,  spherical  in  shape. 


THE  ARCHITECTURE   AND  FUNCTIONS  OF  THE  CEREBELLUM. 

The  cerebellum  or  ** hinder-brain"  consists  of  two  lateral 
hemispheres,  joined  together  by  an  intermediate  portion  which 
is  called,  from  a  fancied  resemblance  to  a  worm,  the  "  vermi- 
form process."  The  peculiar  appearance  of  this  process  is  due 
partly  to  its  shape  and  partly  to  transverse  ridges  and  furrows 
which  are  very  apparent.  When  the  under  surface  of  the 
cerebellum  is  examined,  this  process  appears  as  a  well-marked 
projection,  the  'inferior  "cermiform  process. ^^  On  the  upper 
surface  it  is  only  slightly  elevated,  forming  the  so-called  ''  svr 
perior  mrmiform  process. "^^  In  birds,  as  well  as  in  some  ani- 
mals lower  in  the  scale,  the  vermiform  process  alone  exists.' 
It  is  the  part  first  developed  in  mammals.  In  most  mammals, 
moreover,  it  constitutes  a  distinct  central  lobe,  clearly  demar- 
kated  from  the  lateral  portions — the  hemispheres  of  the  cere- 
bellum. 

The  cerebellar  hemispheres  are  separated  behind  by  a  deep 
notch.  Below,  a  deep  fossa  (the  vallecula),  which  is  continu- 
ous with  the  notch  seen  posteriorly,  lodges,  the  inferior  vermi- 
form process.  This  hollow  also  receives  the  medulla  in  front, 
and  the  falx  cerebelli  behind.  The  hemispheres  are  convex 
on  their  lower  surface,  and  tend  to  partly  conceal  the  inferior 
vermiform  process  ;  above,  however,  they  are  somewhat  flat- 
tened in  the  center,  and  slope  downward  toward  the  sides, 

'  The  vermiform  process  appears  to  bo  a  complete  ganglion  in  itself,  associated  with 
its  own  nerve  tracts.  The  cerebellar  hemisplia-es  are  added,  in  the  higher  grades  of  ani- 
mals, in  proportion  to  the  development  of  the  cerebral  lobes. 


THE  CEREBELLUM. 


217 


causing  the  slightly  elevated  superior  vermiform  process  to 
be  less  distinctly  outlined  than  the  inferior  process  is. 

The  cerebellum  measures  about  three  and  a  half  inches 
transversely,  about  two  and  a  half  inches  from  before  back- 
ward, and  about  two  inches  in  depth  at  its  thickest  portion, 
although  it  thins  out  at  its  lateral  borders. 


Fig.  4Y. —  Cerehellum  and  medulla  oblongata.     (Hirschfeld.) 

1,  1,  corpus  dentatum  ;  2,  tuber  annulare ;  3,  section  of  the  middle  peduncle ;  4,  4,  4, 4, 4, 
laminae  forming  the  arbor  vitae ;  5,  6,  olivary  body  of  the  medulla  oblongata ;  6,  an- 
terior pyramid  of  the  medulla  oblongata ;  7,  upper  extremity  of  the  spinal  cord. 


The  surfaces  of  the  cerebellum  are  everywhere  marked  by 
deep,  closely  set,  transverse,  and  somewhat  curved  fissures. 
These  are  often  of  considerable  depth,  the  larger  ones  conceal- 
ing many  folia  which  do  not  reach  the  surface  of  the  cerebel- 
lum. Some  of  these  fissures  are  better  marked  than  the  rest, 
the  most  conspicuous  one  being  the  great  horizontal  fissure^ 
which  starts  in  front  at  the  middle  peduncle,  and  extends 
around  the  outer  and  posterior  border  of  each  hemisphere, 
being  prolonged  into  the  posterior  notch,  where  it  joins  with 
its  fellow  of  the  opposite  side.  This  fissure  separates  the 
cerebellum  into  an  upper  and  lower  portion,  which  correspond 
to  the  upper  and  lower  surfaces.  Each  of  these  portions  is 
likewise  subdivided  by  fissures,  somewhat  more  distinct  than 
the  rest,  into  small  lobes.     The  names  of  these  lobules  can  be 


218  THE  BRAIN. 

found  in  any  work  upon  descriptive  anatomy.  The  tonsillar 
and  flocculV  are  the  more  important.  The  vermiform  pro- 
cess, or  ''worm,"  is  also  subdivided  into  lobules.  Physio- 
logical experiment  or  pathological  research  has  not  yet  posi- 
tively located  any  special  functions  in  these  lobules,  so  that 
they  are  of  use  chiefly  in  describing  the  situation  of  lesions 
of  the  cerebellum  and  the  course  of  fibers  to  the  cerebellar 
cortex. 

Sections  made  through  the  substance  of  the  cerebellum 
show  a  beautifully  foliated  or  arborescent  appearance  ;  named 
''arbor-vitae"  in  consequence  of  the  medullary  or  white  sub- 
stance of  the  ganglion  being  prolonged  into  the  laminse.  The 
main  branches  of  the  medullary  substance,  or  groups  of  them, 
correspond  to  the  lobules  of  the  cerebellum.  These  are  con- 
nected, as  the  cerebral  convolutions  are,  by  festoon-like  fibers 
(fibrse  proprise).  The  medullary  substance  is  more  abundant 
in  the  hemispheres  than  in  the  worm  (vermiform  process). 

In  the  center  of  each  hemisphere  a  nucleus  of  gray  matter, 
the  so-called  '' corpus  dentatum,'*^  is  seen  in  all  vertical  and 
transverse  sections  of  that  region.  In  structure  it  resembles 
that  of  the  olivary  body  of  the  medulla  oblongata,  having  a 
wavy  layer  of  yellowish-brown  substance  externally,  and 
white  matter  in  its  center.  At  its  upper  and  inner  part  this 
wavy  layer  is  interrupted,  so  that  the  plicated  capsule  is  not 
complete.  The  fibers  which  are  contained  within  the  processes 
cerebelli  ad  cerebrum  (superior  peduncle  of  cerebellum)  and 
the  valve  of  Vieussens  may  be  traced,  in  part,  to  the  corpus 
dentatum. 

Stilling,  who  has  made  elaborate  researches  respecting  the 
minute  structure  of  the  cerebellum,  describes  three  other  col- 
lections of  gray  matter  within  the  white  center  of  the  hemi- 
spheres. These  are  named  the  ''nucleus  emboliformis^^^  the 
''nucleus  globosus,'"  and  the  "nucleus  fastigiV  These 
nuclei  are  not  distinctly  isolated  in  all  parts,  but  are  con- 
nected here  and  there  with  one  another,  and  with  the  corpus 

'  The  Jloceuhm  is  believed  by  some  authors  to  be  directly  associated  with  a  fasciculus 
derived  from  the  pneumogastric  nerve. 


CEREBELLAR  NUCLEI  AND   CORTEX.  219 

dentatum.  Their  functions  are  not  yet  determined.  The 
" nucleus  fastigW^  i^  often  called  the  ''nucleus  of  the  ven- 
tricular roof "  (Spitzka).  It  is  situated  in  the  white  mass  of 
the  worm,  and  lies  in  the  roof  of  the  fourth  ventricle.  It 
probably  receives  fibers  of  the  auditory  nerve  root  and  the 
trapezium.  This  nucleus  is  separated  from  its  fellows  by  a 
thin  septum  of  white  matter.  The  other  two  nuclei  described 
by  Stilling  lie  in  intimate  relation  with  the  dentate  nucleus  of 
the  hemisphere. 

The  cerebellum,  as  a  whole,  is  described  as  possessing 
three  peduncles.  These  are  collections  of  nerve  fibers  which 
pass  out  from,  or  into,  the  substance  of  the  hemispheres. 

The  superior  peduncles  {processi  cerehelU  ad  cerehrum) 
are  directed  upward  and  forward  from  the  mesial  part  of  the 
hemispheres. 

The  middle  peduncles  {processi  cerehelU  ad  pontem) 
emerge  from  the  lateral  part  of  the  hemispheres  and  pass  to 
the  pons  Varolii. 

The  inferior  peduncles  {processi  cerehelU  ad  medullam) 
escape  from  the  hemispheres  of  the  cerebellum  between  the 
other  two,  pass  forward  outside  of  the  superior  peduncles  to 
reach  the  lateral  wall  of  the  fourth  ventricle,  and  then  turn 
sharply  downward  to  become  the  so-called  "restiform  bodies" 
of  the  medulla  oblongata.  Each  of  these  processes  will  be 
considered  separately. 

We  are  now  prepared  to  consider  the  minute  structure  of 
the  cerebellum  and  its  processes.  The  various  theories  which 
have  been  advanced  in  regard  to  the  probable  functions  of  this 
ganglion  can  be  intelligently  discussed  only  after  some  knowl- 
edge of  its  connections  with  other  regions  of  the  cerebro- 
spinal system.  Experimental  physiology  frequently  conflicts 
with  the  observed  effects  of  pathological  lesions  of  the  nerve 
centers. 

THE   CEREBELLAR   CORTEX. 

The  external  gray  matter  of  the  cerebellum  differs  in  its 
microscopical  appearance  from  that  of  the  cerebrum,  which 
has  been  described  in  a  previous  lecture.     It  consists  of  three 


220  THE  BRAIK 

layers — an  outer,  composed  of  both  cells  and  fibers ;  a  middle, 
consisting  of  large  cells,  termed  the  "  corpuscles  of  Purkinje  " ; 
and  an  inner,  which  is  reddish-gray  in  color  and  of  a  granular 
structure. 

In  the  outer  layer  most  of  the  fibers  have  a  direction  at 
right  angles  to  the  surface  of  the  cerebellum.  The  greater 
proportion  of  these  fibers  are  simply  the  prolongation  of  the 
processes  of  the  large  cells  of  the  middle  layer  (cells  of  Pur- 
kinje). Others  are  fine,  tapering  fibers,  which  seem  to  rest 
by  a  broad  base  on  the  pia  mater,  w^hich  covers  the  outer 
layer.  These  fibers  make  up  a  dense  felting,  inclosing  free 
nuclei  and  scattered  cells.  The  cells  of  this  layer  are  granule- 
like bodies,  the  larger  of  which  are  apparently  connected  with 
the  processes  of  the  cells  of  Purkinje.  The  smaller  probably 
belong  to  the  matrix  ;  the  larger  are  supposed  to  be  nervous 
in  function.  Along  the  innermost  portion  of  the  outer  layer 
nerve  fibers  may  be  also  demonstrated,  which  run  parallel 
with  the  surface  of  the  cerebellum. 

The  middle  layer  is  characterized  by  the  peculiar  cells' 
found  imbedded  in  it— the  "cells  of  Purkinje."  Most  of 
these  cells  are  flask-shaped,  although  a  few  are  irregular  in 
form.  The  long  axis  of  the  cell  is  placed  at  a  right  angle  to 
the  free  surface  of  the  cerebellum.  The  diameter  of  these  cells 
varies  from  -^  to  j^^  of  an  inch.  Two  sets  of  processes  may 
be  demonstrated  as  arising  from  these  cells,  viz.,  one  passing 
through  the  outer  layer  of  the  cerebellar  cortex  and  one  pass- 
ing through  the  inner  layer.  The  former  are  of  large  size,  and 
are  connected,  in  some  instances,  with  the  corpuscles  of  the 
outer  layer  ;  others  pass  directly  through  the  layer  to  become 
lost  at  its  surface.  In  either  case  they  subdivide  repeatedly 
in  their  passage  through  the  outer  layer.  The  inner  set  of 
processes  are  fine  and  undivided,  and  pass  into  the  granule 
layer,  where  some  probably  become  continuous  with  the  axis- 
cylinders  of  nerve  fibers  composing  the  medullary  portion. 

*  The  bodies  of  these  cells  are  colossal  (sixty  to  seventy  millimetres  in  length,  and 
twenty  to  thirty  millimetres  in  thickness).  They  appear  to  be  inclosed  within  a  loose- 
fitting  capsule,  formed  of  connective-tissue  fibers  (Oborsteiner). 


LAYERS  OF  CEREBELLAR   CORTEX.  221 

The  inner  layer^  called  the  ''granule  layer,"  lies  next  to 
the  medullary  center  of  the  cerebellum.'  It  consists  of  gran- 
ule-like corpuscles,  which  are  imbedded  in  groups  in  a  gelati- 
nous matrix.  Nerve  fibers  can  be  demonstrated  to  join  with 
the  processes  of  the  cells  of  Purkinje  within  this  layer.  The 
cells  of  this  layer  are  both  round  and  angular.  Each  consists 
of  a  nucleus,  a  thin  envelope  of  protoplasm,  and  processes 
which  unite  with  the  plexus  of  nerve  fibers  in  its  vicinity. 
They  measure  from  -c^-^  to  -f-}-^-^  of  an  inch. 

It  will  be  evident,  after  this  hasty  description,  that  the 
cortex  of  the  cerebellum  differs  markedly  from  that  of  the 
cerebrum,  in  spite  of  the  various  structural  types  of  the  latter. 
The  cells  of  Purkinje  are  characteristic  of  the  cerebellum 
alone.    The  number  of  layers  is  less  than  in  the  cerebral  cortex. 

We  are  apparently  justified  in  attributing  to  the  cerebel- 
lum some  functional  attributes  of  a  special  type,  because 
similar  anatomical  elements  are  to  be  found  in  no  other 
region.  The  theories  which  have  been  advanced  respecting 
the  functions  of  this  ganglion  will  be  considered  later. 

In  cross-sections  of  each  fold  or  lamina  of  the  cerebral  cor- 
tex may  be  seen  a  central  medullary  or  white  portion,  resem- 
bling the  stem  and  diverging  branches  of  a  twig,  with  its  at- 
tached leaves.  This  ^''medullary  center ^^  can  be  shown  to 
consist  of  bundles  of  fibers  which  run  parallel  with  each  other 
or  interlace,  until  they  turn  obliquely  into  the  gray  matter  of 
the  cortex.  It  is  still  undecided  whether  these  fibers  termi- 
nate in  the  "granule  layer"  of  the  cortex,  becoming  joined 
to  the  axis- cylinder  processes  of  the  cells  of  Purkinje,  or  by  a 
union  with  the  plexus  of  fine  fibers  described  as  existing  in 
the  outer  layer. 

THE   CEl^TRAL  WHITE   SUBSTAITCE   OF  THE   CEREBELLUM. 

The  peduncles  of  the  cerebellum  have  been  mentioned  in 
the  early  part  of  this  lecture,  but  much  remains  to  be  said  re- 

^  The  striking  resemblances  between  this  layer  and  the  granular  strata  of  the  olfac- 
tory lobe  have  been  commented  upon  by,Meynert.     The  cells  of  this  layer  are  regarded  by 
Gcrlach  as  connective-tissue  elements ;  by  Ilenle  and  Merkel  as  lymphoid  elements ;  and 
by  Stilling  as  small  multipolar  nerve  cells. 
17 


THE  BRAIK 

specting  the  probable  course  of  the  fibers  contained  in  each, 
during  their  passage  through  the  white  or  medullary  center 
of  the  cerebellum.  The  course  which  they  pursue  outside 
of  the  limits  of  this  ganglion  will  also  merit  subsequent 
attention. 

The  fibers  of  the  superior  peduncle  can  be  traced  almost 
entirely  into  the  interior  of  the  '*  nucleus  dentatum";  al- 
though a  few  can  be  demonstrated  to  pass  around  the  outer 
side  of  this  central  mass  of  gray  matter  without  entering  it, 
and  some  mesial  fibers  can  be  shown  to  enter  directly  into  the 
white  substance  of  the  vermiform  process.  As  was  stated  to 
be  the  case  with  the  corpus  striatum  and  the  optic  thalamus, 
it  is  probable  that  a  few  of  the  fibers  which  apparently  enter 
the  substance  of  the  nucleus  dentatum  do  not  become  joined 
with  the  cells  of  that  body,  but  simply  pass  through  it  to  go 
to  the  cerebellar  cortex ;  on  the  other  hand,  it  is  equally 
probable  that  most  of  the  fibers  which  enter  it  become  associ- 
ated more  or  less  intimately  with  the  cells  found  within  that 
body,  and  that  they  are  subsequently  continued  to  a  periph- 
eral termination  in  some  part  of  the  cortex.  The  fibers  which 
inclose  the  nucleus  dentatum  are  so  matted  together  into  a 
network  that  it  is  impossible  to  trace  the  course  of  even  dis- 
tinct bundles  from  their  entrance  into  the  cerebellum  to  their 
termination  in  the  cortex.  The  course  of  these  fibers  through 
the  cms  has  been  described  in  preceding  pages. 

The  fibers  of  the  middle  peduncle  leave  the  pons  to  enter 
the  lateral  part  of  the  white  substance  of  the  cerebellum  as 
two  main  bundles.  One  is  composed  of  the  superior  trans- 
verse fibers  of  the  pons  ;  the  other  consists  of  the  lower  trans- 
verse fibers  of  the  pons  mingled  with  those  of  the  inferior 
peduncle  of  the  cerebellum  {restiform  body  of  the  medulla). 
The  upper  bundle  passes  obliquely  downward  over  the  lower, 
and  enters  the  lateral  and  anterior  portions  of  the  medullary 
center  of  the  hemisphere.  The  lower  bundle,  after  joining 
with  the  fibers  of  the  restiform  body  of  the  medulla  oblon- 
gata, turns  upward,  and  radiates  into  the  upper  part  of  the 
medullary  center  of  the  corresponding  hemisphere  of  the  cere- 


FIBERS  OF  THE  CEREBELLUM.  223 

bellum  and  the  upper  part  of  the  vermiform  process.  Stilling 
states  that  the  fibers  of  the  restiform  body  pass,  in  part,  into 
the  nucleus  dentatum,  while  the  rest  curve  over  the  nucleus, 
— the  so-called  ''  semicircular  fibers." 

Finally,  certain  commissural  fibers  are  described  by  Stil- 
ling as  existing  in  the  cerebellum.  These  may  be  divided  into 
two  sets.  The  first  are  analogous  to  the  commissural  fibers  of 
the  cerebrum,  crossing  the  median  line  and  probably  joining 
homologous  regions  of  the  cerebellar  cortex  in  the  two  hemi- 
spheres ;  the  second,  analogous  to  the  collateral  fibers  of  the 
cerebrum,  connecting  one  lamina  of  the  cortex  with  another, 
and  arching  around  the  fissures  between  the  laminae.  The 
latter  set  are  confined  to  one  hemisjjhere,  and  dp  not  cross 
the  median  line  of  the  cerebellum.  The  direction  of  these 
fibers  is  transverse  to  that  of  the  ''peduncular"  cerebellar 
fibers. 

It  is  evident,  therefore,  that  the  general  arrangement  of 
the  cerebellar  fibers  bears  a  striking  resemblance  to  that  of 
the  cerebrum ;  the  nucleus  dentatum^  olivary  body,  red  nu- 
cleus^ and  gray  matter  of  the  pons  being  the  analogues  of  the 
basal  ganglia  of  the  cerebrum,  and  the  ''radiating,"  "com- 
missural," and  "associating  systems "  being  similar  in  many 
respects.  The  cerebellum,  like  the  cerebrum,  may  be  said, 
therefore,  to  exhibit  three  so-called  "projection  systems" 
of  fibers,  as  follows  :  1.  The  inner  projection  system,  the 
fibers  of  which  serve  to  connect  the  cortex  of  the  cerebel- 
lum with  the  nucleus  dentatus  of  the  same  hemisphere  and 
the  olivary  body,  the  red  nucleus  of  the  tegmentum,  and  the 
anterior  gray  substance  of  the  pons  Varolii  of  the  opposite 
side ;  2.  The  middle  projection  system,  the  fibers  of  which 
connect  the  enumerated  masses  of  gray  matter  with  the  gray 
matter  of  the  crus,  pons,  and  spinal  cord ;  3.  The  outer  pro- 
jection system,  the  fibers  of  which  are  included  in  the  expan- 
sions of  the  central*  tubular  gray  matter  to  the  periphery  of 
the  body  by  means  of  the  spinal  nerves. 

The  following  diagram  will  help  to  make  certain  points 
clear  regarding  the  intimate  structure  of  the  cerebellum  and 


224 


THE  BRAIK 


its  connections  with  adjoining  parts.     It  is,  of  course,  purely 
schematic,  but,  if  used  in  connection  with  actual  representa- 


CRURA  CEREBRI 


Fig.  48. — A  diagram  designed  hy  the  author  to  illustrate  the  various  sets  of  Jihers  com- 
prised within  the  cci'cbello-spinal  system.      (Modified  from  Ross.) 

c.  R.,  crusta  cruris ;  t,  e.  g.,  tegmentum  cruris ;  a.  s.,  aqueduct  of  Sylvius  surrounded  by  the 
tubular  gray  matter ;  s.  N.,  substantia  nigra ;  r.  n.,  red  nucleus  of  the  tegmentum ; 
o.  M.  p.,  anterior  gray  matter  of  the  pons ;  c.  c,  cerebclla  cortex  ;  n.  d.,  nucleus  denta- 
tum ;  0.  B.,  olivary  body ;  c.  n.,  clavate  nucleus ;  t.  n.,  triangular  nucleus ;  d.  c.  t.,  fibers 
of  the  "direct  cerebellar  tract"  of  the  spinal  cord;  p.  r.  z.,  fibers  of  the  "posterior 
root  zone"  of  the  same;  g.,  fibers  of  the  "column  of  GoU";  1,  cerebro-ccrebel- 
lar  fibers ;  2,  fibers  from  the  red  nucleus  of  the  tegmentum  to  the  dentate  nucleus  of 
the  cerebellum ;  3,  fibers  from  the  red  nucleus  to  the  cerebellar  coi-tex ;  4,  fibers 
from  the  cerebellar  cortex  to  the  dentate  nucleus ;  5,  fibers  from  the  dentate  nucleus 
to  the  olivary  body  of  the  opposite  side ;  6,  fibers  from  the  cerebellar  cortex  to  the 
olivary  body  of  the  opposite  side ;  7,  fibers  from  the  cerebellar  cortex  to  the  anterior 
pray  nucleus  of  the  pons  of  the  opposite  side ;  8,  fibers  of  the  direct  cerebellar  tract ; 
9,  fibers  connecting  the  clavate  nucleus  and  the  olivary  body  of  the  same  side ;  10, 
fibers  connecting  the  triangular  nucleus  and  the  olivary  body  of  the  same  side;  11, 
fibers  passing  from  the  olivary  body  to  the  horns  of  the  spinal  gray  matter; 
1 2,  fibers  passing  from  the  anterior  gray  matter  of  the  pons  to  the  horns  of  spinal 
gray  matter;  13,  fibers  passing  from  the  red  nucleus  of  the  tegmentum  to  the  ante- 
rior horns  of  the  spinal  gray  matter;  14,  fibers  escaping  from  the  spinal  cord  through 
the  anterior  root  of  a  spinal  nerve ;  1 5,  fibers  of  the  posterior  root  of  a  spinal  nerve 
entering  at  the  posterior  horn  of  the  spinal  gray  matter.  The  dots  in  the  cut  end  of 
the  spinal  cord,  near  to  15,  indicate  the  relative  position  of  the  different  tracts  with 
which  they  are  connected,  a,  a,  a,  represent  fibers  which  are  destined  to  connect 
different  convolutions  of  the  cerebellar  cortex  {Jibrce  proprice). 


FIBERS  OF  TEE  CEREBELLUM.  225 

tions  of  the  parts,  it  will  prove  of  great  value  in  comprehend- 
ing many  statements  which  are  to  follow.  In  this  diagram 
the  shaded  parts  represent  collections  of  gray  matter ;  the 
lines  indicate  the  direction  and  extent  of  individual  sets  of 
nerve  fibers  which  are  in  direct  communication  with  the 
shaded  masses. 

The  arrangement  of  the  middle  projection  system  of  fibers 
pertaining  to  the  cerebello-spinal  apparatus  is  less  definitely 
settled  than  that  of  the  cerebro-spinal.  It  is  probable,  how- 
ever, that  the  cerebellum  receives  afferent  sets  of  fibers  from 
the  spinal  cord,  and  gives  off  also  certain  efferent  sets  of 
fibers,  which  are  brought  into  more  or  less  direct  communica- 
tion with  the  motor  tracts  of  the  crura,  pons  Varolii,  medulla, 
and  spinal  cord. 

The  AFFEREis^T  FIBERS  of  the  Cerebellum  probably  reach 
that  ganglion  through  the  following  channels  (Fig.  48) : 

1.  By  means  of  the  columns  of  Goll  (a.),  which  terminate 
in  the  so-called  ''  clavate  nucleus  "^^  (c.  n.). 

2.  By  means  of  the  columns  of  BurdacJi  or  the  posterior 
root  zone  of  the  spinal  cord  (p.  r.  z.),  which  seems  to  be  struct- 
urally related  with  the  so-called  "triangular  nucleus ^^ 
(t.  n.). 

3.  By  means  of  fibers  which  connect  the  triangular  and 
clavate  nuclei  with  the  "-olivary  hody^'^  of  the  corresponding 
side  of  the  medulla  oblongata  (9  and  10). 

4.  By  means  of  the  '^direct  cerebellar  tract ''^  of  fibers 
(d.  c.  t.)  which  is  found  within  the  lateral  column  of  the 
spinal  cord  near  to  the  extremity  of  the  posterior  horn  of  the 
spinal  gray  matter. 

5.  By  means  of  fibers  connected  with  the  auditory  and 
possibly  with  the  sensory  root  of  the  fifth  cranial  nerves. 
The  auditory  fibers  are  probably  associated  chiefly  with  the 
corpus  dentatum  and  the  nucleus  fastigii.  It  is  stated  that 
they  decussate  either  in  the  medulla  or  cerebellum.  If  so, 
they  pass  through  the  auditory  nucleus  before  entering  the 
cerebellum.  The  apparatus  of  hearing  performs  an  important 
part  in  equilibration. 


THE  BRAIN, 

The  EFFERENT  FIBERS  of  the  Cerebellum'  are  probably 
comprised  within  the  following  fasciculi : 

1.  Bundles  of  fibers  which  connect  the  dentate  nucleus 
and  the  cerebellar  cortex  with  the  corpus  striatum  or  optic 
thalamus  by  means  of  the  ''processus  cerebelli  ad  cerebrum." 
This  bundle  is  also  in  intimate  relation  with  the  ''red  nucleus 
of  the  tegmentum,"  and  probably  is  structurally  related  with 
some  of  the  nerve  cells  found  in  that  nucleus  (2  in  Fig.  48). 
Luys  believes  that  the  corpus  striatum  is  charged,  when  its 
nervous  force  becomes  exhausted,  by  means  of  this  process  of 
the  cerebellum.  If  this  be  the  case,  the  cerebellum  exerts 
some  influence  upon  the  impulses  emitted  from  the  cerebral 
hemispheres ;  because  many  such  impulses  are  probably 
modified  within  the  corpora  striata  before  they  are  trans- 
mitted to  the  more  distant  parts  of  the  nervous  apparatus  (the 
gray  matter  of  the  spinal  cord,  and  the  spinal  nerves).  The 
probable  relations  of  cerebral  and  cerebellar  influences  upon 
muscles  will  be  discussed  later. 

2.  Fibers  which  probably  connect  the  red  nucleus  of  the 
tegmentum  with  the  anterior  horns  of  the  spinal  gray  matter 
(13  in  Fig.  48). 

3.  Fibers  which  probably  connect  the  olivary  bodies  of 
the  medulla  oblongata  with  the  anterior  horns  of  the  spinal 
gray  matter  (11  in  Fig.  48). 

4.  Fibers  which  connect  the  anterior  gray  substance  of 
the  pons  Varolii  with  the  anterior  horns  of  the  spinal  gray 
matter  (12  in  Fig.  48). 

From  the  imperfections  of  our  present  knowledge,  much 
that  is  stated  here  regarding  the  exact  course  of  the  afferent 
and  efferent  impulses  of  the  cerebellum  must  be  somewhat 
conjectural.  The  results  of  experimental  physiology  and  of 
pathological  research  are  not,  and  can  not  well  be,  of  a  posi- 
tive character.     Many  conflicting  theories  have  been  at  dif- 

*  If  the  brain  be  considered  as  a  whole,  fibers  passing  from  the  cerebellum  to  the 
cerebrum  by  means  of  the  superior  and  middle  peduncles,  as  well  as  those  passing  to 
the  tubercular  quadrigeniina,  by  means  of  the  valve  of  Vicusscns,  may  be  classed  as 
afferent  fibers.  Spitzka  denies  the  existence  of  efferent  cerebellar  fibers  (outside  of  the 
superior  and  middle  peduncles). 


PEDUNCLES  OF  THE  CEREBELLUM. 


227 


ferent  times  advanced  regarding  the  functional  attributes  of 
this  ganglion.  These  will  be  considered  when  the  anatomical 
data  have  been  more  fully  presented. 

Processus  cerebelli  ad  cerebrum,  {processus  e  cerebello  ad 
testes^  superior  peduncle  of  cerebellum). — In  connection  with 
previous  topics,  chiefly  in  those  pages  which  treat  of  the  corpus 
striatum  and  the  optic  thalamus,  the  relation  of  the  cere- 
bellum with  the  medullary  portion  of  the  cerebrum  by  means 
of  special  fibers  has  been  mentioned.  The  special  group  of 
fibers  which  compose  the  processus  cerebelli  ad  cerebrum  ap- 
pear to  start  anteriorly  from  among  the  radiating  fibers  of  the 
cerebrum  and  are  forced  apart,  in  the  region  of  the  crus, 
above  the  corpora  quadrigemina,  by  the  introduction  of  a 
nodal  mass  of  gray  matter,  characterized  by  nerve  cells  and 
granular  material,  the  so-called  '-''red  nucleus  of  the  tegmen- 


FiG.  49. — A  ci'ude  diagram  designed  hy  the  author  to  illustrate  the  three  pairs  of  pedun- 
cles of  the  cerebellum. 

Those  of  one  side  only  are  shown. 

tum.''^  In  the  region  of  the  lower  half  of  the  superior  corpus 
bigeminum  this  tract  appears  as  a  simple  bundle  of  fibers, 
which  are  not  destitute  of  nerve  cells,  but  whose  circumfer- 
ence is  much  less  than  in  the  reejion  of  the  red  nucleus.     The 


328  THE  BRAJN-. 

nerve  cells  of  this  bundle  are  of  extreme  size,  and  appear  to 
be  arranged  parallel  with  the  vessels  of  that  region  rather 
than  with  the  nerve  fibers.  In  some  cases  they  bend  to  fit  the 
angles  of  the  branches  of  the  arteries,  and  send  out  long  pro- 
longations that  run  longitudinally  along  and  probably  in 
their  walls  (Meynert).  Even  in  the  ''red  nucleus"  this  ar- 
rangement may  be  demonstrated.  The  presence  of  nerve  cells 
within  this  tract  does  not  cease  until  after  its  decussation  and 
its  escape  from  the  corpus  quadrigeminum.  It  yet  remains 
to  be  demonstrated  whether  the  crural  portion  of  the  pro- 
cessus cerebelli  ad  cerebrum  is  the  only  seat  of  a  peripheral 
termination  of  nerve- cell  processes  in  the  walls  of  capillaries 
in  the  midst  of  the  central  organ. 

If  successive  cross-sections  of  the  region  occupied  by  this 
tract  be  studied,  it  will  be  seen  that  the  processus  cerebelli 
ad  cerebrum  of  either  side  approaches  the  median  line,  and 
that  the  fibers  eventually  decussate.  The  region  occupied  by 
these  decussating  fibers  lies  between  the  "posterior  longitudi- 
nal fasciculus  ^^  and  the  "stratum  lemnisci^^^  the  remaining 
bundles  of  spinal  fibers  which  enter  the  tegmentum  having 
been  crowded  away  by  them.  After  their  decussation,  these 
fibers  pass  outward  until  they  reach  the  inner  surface  of  the 
inferior  lamina  of  the  lemniscus,  which  forms  a  sort  of  pro- 
tective cover  for  them.  Meynert  has  compared  the  outline  of 
the  two  processes  to  the  form  of  a  horseshoe,  whose  opening 
is  directed  backward.  This  opening  represents  an  area  which 
embraces  those  fibers  of  the  "tegmentum  cruris"  directly  pro- 
longed from  the  spinal  cord ;  bounded  by  the  stratum  lem- 
nisci  and  the  posterior  longitudinal  fasciculus.  The  decus- 
sating fibers  of  the  cerebellar  tract  force  their  way  among  the 
fibers  of  the  tegmentum  cruris  to  reach  their  lateral  position  ; 
hence,  cross-sections  made  at  diiferent  altitudes  show  ever- 
varying  relations  between  these  fibers  and  those  of  the  teg- 
mentum. Stilling  and  Arnold,  who  have  made  a  special  study 
of  the  course  of  the  fibers  of  the  processus  cerebelli  ad  cere- 
brum, differ  as  to  the  completeness  of  the  decussation,  the 
latter  denying  that  all  the  fibers  cross  the  median  line.     Mey- 


VALVB  OF  VIEUSSENS.  229 

nert  confirms  the  view,  originally  advanced  by  Stilling,  tliat 
the  decussation  is  complete. 

After  the  decussation  of  its  libers,  each  processus  disen- 
gages itself,  both  superiorly  and  externally,  from  the  fibers 
of  the  tegmentum  cruris  in  which  it  was  imbedded.  Oppo- 
site to  the  point  of  greatest  convexity  of  the  pons  Varolii,  it 
becomes  uncovered  by  the  inferior  lamina  of  the  lemniscus. 
Later  in  its  course  it  becomes  buried  in  the  white  substance 
of  the  cerebellum,  and  finds  an  ultimate  connection  with  the 
*' nucleus  dentatus,"  the  central  mass  of  gray  matter  within 
the  cerebellar  hemisphere. 

When  we  examine  the  fourth  ventricle,  the  exposed  por- 
tion of  this  tract  will  be  seen  to  constitute  the  lateral  bound- 
ary-walls of  that  cavity  {processus  e  cerebello  ad  testes) ;  with 
the  so-called  ''valve  of  Vieussens"  {velum  medullary  ante- 
rius)  inclosed  between  them.  The  latter  formation  deserves 
special  notice  in  this  connection. 

The  processus  cerebelli  ad  cerebrum  itself  is  by  no  means 
free  from  admixture  of  foreign  elements  during  its  passage 
from  the  cerebrum  to  the  cerebellum,  the  details  of  which  I 
have  just  given.  At  the  level  of  origin  of  the  fifth  cranial 
nerve  (trigeminus)  fibers  from  the  cerebellum  apparently  pass- 
ing to  the  greater  root  of  that  nerve  can  be  demonstrated  as 
fasciculi  which  in  part  cover  it  and  in  part  traverse  it.  It 
is  also  traversed,  at  a  lower  plane,  by  fasciculi  destined  to 
belong  to  the  eighth  cranial  nerve  (auditory). 

Valve  of  Vieussens.— In  this  commissural  band  (the  me- 
dullary velum)  three  different  systems  of  fibers  lie  inter- 
woven: 1.  The  great  mass  of  its  substance  is  composed  of 
bundles  of  fibers  derived  from  the  frenulum.  2.  The  decus- 
sating fibers  of  the  fourth  cranial  nerve  (trochlearis),  which 
are  grouped  at  the  anterior  extremity  of  the  valve  into  bun- 
dles of  extreme  thickness,  are  intertwined  transversely  with 
the  fasciculi  of  the  frenulum.  3.  Certain  longitudinal  fibers 
may  be  demonstrated  which  can  be  traced  to  the  superior 
vermiform  process  of  the  cerebellum.  The  course  of  these 
fibers  is  peculiar.    They  decussate  before  leaving  the  superior 


230 


THE  BRATR. 


vermiform  process  ;  they  then  traverse  the  valve  of  Yieussens 
almost  to  the  lower  border  of  the  corpus  quadrigeminum  ;  at 
this  poiut  they  double  upon  themselves,  describing  curves 
whose  convexity  looks  upward  ;  finally,  they  join  the  inferior 
lamina  of  the  lemniscus  at  its  posterior  bundle,  and  pass  on- 
ward with  the  latter,  in  the  posterior  division  of  the  pons 
Varolii,  to  the  spinal  cord. 

Processus  cerehelU  ad  pontem  {middle  ped.uncle  of  cere- 
helium). — When  the  general  architecture  of  the  cerebro  spi- 
nal axis  was  under  consideration,  the  relation  of  the  cerebel- 
lum to  certain  fibers  which  helped  to  form  the  ''  basis  cruris" 
of  Meynert  {crusta  cruris)  was  touched  upon,  as  an  anatomi- 
cal explanation  of  the  fact  that  the  number  of  fibers  of  the 
middle  projection  system  suffered  an  apparent  decrease  dur- 
ing their  passage  through  the  pons  Varolii.  It  was  then 
stated  that  some  of  the  efferent  fibers  of  the  cerebrum  prob- 
ably left  the  direct  tract  of  the  projection  system  within 
the  region  of  the  pons,  and  passed  to  the  cerebellum.  Some 
points  pertaining  to  the  physiological  importance  of  these 
fibers  were  also  mentioned  in  connection  with  my  description 
of  the  corpus  striatum.  It  has,  moreover,  been  stated  in  pre- 
vious lectures,  that  the  region  of  the  pons  contained  certain 
transverse  fibers  connected  with  the  cerebellum,  which  inter- 
laced with  the  fibers  of  the  cerebral  projection  tracts,  and 
were  probably  more  or  less  intimately  associated  with  the 
nodal  masses  of  gray  matter  found  in  that  region.  Some  of 
these  fibers  are  unquestionably  commissural  in  character, 
serving  to  unite  homologous  regions  of  the  cerebellar  hemi- 
spheres ;  others  probably  serve  to  unite  the  hemispheres  of 
the  cerebellum  with  the  gray  matter  of  the  pons  of  the  oppo- 
site side.  In  man  the  pons  is  long,  because  the  crusta  cruris 
is  developed  in  proportion  to  the  size  of  the  cerebral  lobes ; 
in  animals  it  becomes  shorter  in  proportion  to  the  decrease  in 
size  of  the  cerebrum.  The  interlacement  of  the  fibers  of  the 
projection  system  with  those  of  the  *' processus  cerebelli  ad 
pontem  "  occupies  the  region  of  the  pons  and  the  upper  half 
of  the  medulla  (Meynert).     It  is  somewhat  curious  to  observe 


THE  EESTIFORM  BODY.  231 

that  the  lateral  regions  of  the  cerebellum  keep  pace  in  their 
development  with  the  cerebral  lobes,  and  the  "nucleus  den- 
tatus'^  of  the  cerebellum  is  developed  in  direct  proportion  to 
that  of  the  olivary  bodies  of  the  medulla  oblongata. 

Cross  sections  of  the  region  of  the  pons  reveal  the  fact 
that  the  transverse  fibers  of  the  processus  cerebelli  ad  pontem 
may  be  divided  into  three  sets,  as  follows :  1,  a  superficial 
layer ;  2,  fibers  which  interlace  with  longitudinal  fibers  escap- 
ing from  the  crus ;  3,  a  deep-seated  layer.  The  superficial 
and  deep  layers  appear  to  be  perfectly  independent  of  any 
association  with  the  fibers  which  belong  to  the  middle  projec- 
tion system  of  the  cerebrum  (those  of  the  crusta  and  tegmen- 
tum cruris).  Meynert,  however,  brings  forward  certain  rea- 
sons, based  upon  a  minute  study  of  the  general  relations  of 
these  layers,  which  apparently  lend  support  to  the  view  that 
the  fibers  of  these  strata  are  in  communication  with  nerve- 
cells  embedded  in  the  pons,  that  certain  crural  fibers  are  like- 
wise Joined  to  these  cells,  and  that  the  two  sets  of  fibers  are 
thus  brought  into  communication  with  each  other.  He  states 
his  conclusion  as  follows  : 

''Each  fasciculus  of  the  basis  cruris  cerebri  that  termi- 
nates in  either  side  of  the  anterior  division  of  the  pons  is  rep- 
resented in  the  cerebellar  liemisphere  of  tJie  opposite  side  by 
two  fasciculi,  one  of  which  runs  with  the  superficial,  the 
other  with  the  deep  stratum  of  the  transverse  system  of  fibers 
from  the  point  of  their  connection  with  the  crural  fasciculus 
into  the  processus  cerebelli  ad  pontem  of  the  opposite  side." 

Processus  cerebelli  ad  medullam  {restiform  body,  inferior 
peduncle  of  the  cerebellum). — A  complete  description  of  this 
important  bundle  properly  belongs  to  a  subsequent  lecture, 
which  shall  treat  of  the  architecture  of  the  medulla  oblon- 
gata. It  is  a  round  and  prominent  cord,  which  passes  direct- 
ly into  the  corresponding  hemisphere  of  the  cerebellum.  The 
fibers  of  the  direct  cerebellar  tract  and  the  arched  fibers  of 
the  medulla  oblongata  can  positively  be  traced  through  it  to 
the  substance  of  the  cerebellum.  The  distribution  of  some 
other  bundles  found  within  it  is  still  unsettled.     The  fibers 


238  THE  BRAIN.  ^^^H 

of  the  restifonn  body  probably  terminate  either  in  the  corpus 
dentatum,  the  cortex  of  the  posterior  surface  of  the  hemi- 
sphere, or  the  central  gray  matter  of  the  worm. 

RELATIONS  OF  THE  CEREBELLUM  TO  CRANIAL  NERVES. 

At  various  times  articles  have  appeared  which  tend  to 
show  that  the  fibers  of  origin  of  some  of  the  cranial  nerves 
can  be  traced  to  the  cerebellum.  When  a  positive  demon- 
stration of  the  statements  made  by  some  of  the  later  anato- 
mists can  be  furnished,  much  light  will  be  shed  upon  the 
functions  of  this  ganglion.  There  seems  to  be  every  reason, 
at  present,  to  believe  that  the  auditory  nerve  can  be  traced 
to  the  cerebellum  after  its  fibers  have  passed  through  the  au- 
ditory nucleus  ;  and  the  number  of  such  fibers  appears  to  be 
in  excess  of  those  actually  comprised  within  the  nerve  itself. 
In  this  respect  a  strong  analogy  is  presented  between  the  au- 
ditory fibers  and  those  of  the  coronary  radiata  of  the  cere- 
brum, which  are  themselves  more  numerous  than  those  of  the 
crus,  although  they  appear  to  be  in  direct  continuity  with 
them  (as  was  stated  when  the  basal  ganglia  of  the  cerebrum 
were  under  consideration).  The  opinion  advanced  by  Spitz- 
ka,  that  the  fibers  of  the  sensory  root  of  the  trigeminus  can 
be  also  traced  to  the  cerebellum,  lacks  positive  confirmation 
as  yet ;  and  the  same  remark  might  apply  with  equal  justness 
to  the  views  of  those  observers  who  believe  that  the  thirds 
fourth^  and  tenth  cranial  nerves  have  a  direct  association 
with  that  ganglion.  There  are  physiological  experiments  on 
record  which  seem  to  sustain  all  of  these  views ;  as  well  as  oth- 
ers which  combat  them.  These  will  be  explained  later.  The 
proof,  however,  that  fibers  of  the  nerves  mentioned  can  be 
actually  demonstrated  within  the  substance  of  the  cerebellum 
cannot,  to  my  mind,  be  considered  as  final,  although  some 
neurologists  are  inclining  more  strongly  of  late  toward  that 
belief. 

THE  FUNCTIONS  OF  THE  CEREBELLUM. 

From  the  date  of  Flourens's  first  experiments  upon  the 
cerebellum  of  animals  down  to  the  present  time,  neither  sen- 


FUNCTIONS  OF  THE  CEREBELLUM,  233 

sibility  nor  marked  excitability  seems  to  have  been  demon- 
strated as  attributes  of  this  ganglion.  Animals  which  have 
suffered  extreme  mutilation  of  the  cerebellum  experience  no 
apparent  pain,  nor  does  direct  irritation  of  that  ganglion  re- 
sult in  pain  or  convulsive  movements.  The  opinion  that  the 
cerebellum  is  incapable  of  direct  stimulation,  which  is  still 
held  by  some  physiologists,  seems  to  be  confuted,  however, 
by  the  experiments  of  Budge,  who  observed  that  movements 
of  the  testicle  and  vas  deferens  occurred  in  the  male,  and  of 
the  horn  of  the  uterus  and  the  Fallopian  tubes  in  the  female, 
when  direct  irritation  of  the  cerebellum  was  employed.  The 
same  observer  produced  movements  in  the  stomach  and 
CBsophagus  by  means  of  cerebellar  stimulation. 

The  widest  differences  in  opinion  exist  among  physiolo- 
gists and  neurologists  regarding  the  functions  of  this  gan- 
glion, since  the  most  positive  and  direct  results  of  experi- 
mentation upon  animals  are  apparently  contradicted  by 
pathological  observations  upon  the  human  subject.  There  is 
one  conclusion,  however,  in  which  most  physiological  observ- 
ers, since  the  date  of  Flourens's  original  experiments,  concur, 
viz.,  that  the  cerebellum,  in  some  way,  influences  to  a  marked 
degree  the  cobrdination  of  muscular  movements.  This  is 
very  apparent  in  birds  deprived  of  the  cerebellum  in  whole  or 
in  part ;  since  the  power  of  performing  definite  and  regular 
acts  of  locomotion  is  lost,  although  the  animal  is  not  para- 
lyzed. If  laid  upon  the  back  the  bird  cannot  recover  itself, 
in  spite  of  exhausting  efforts  to  do  so.  If  placed  upon  the 
feet  it  executes  sudden  and  disordered  movements,  and  shows 
an  agitation  which  is  in  marked  contrast  to  the  stupor  which 
follows  a  removal  of  the  cerebral  lobes ;  it  can  still  see  and 
hear,  feel  pain,  exhibit  evidences  of  volition  in  its  endeavors 
to  avoid  a  threatening  blow,  and  apparently  it  possesses  nor- 
mal intellectual  faculties.  Life  is  not  particularly  endan- 
gered by  these  experiments,  as  some  of  Flourens's  birds  lived 
several  months ;  although  severe  haemorrhage  and  injury  to 
the  medulla  may  sometimes  occur  in  performing  them.  If 
only  portions  of  the  cerebellum  are  removed,  the  animal  ap- 


234:  THE  BRAIK 

pears  to  slowly  regain  its  power  of  coordination  of  muscular 
movement ;  this  fact  may  tend  to  explain  the  absence  of 
marked  symptoms  in  the  human  subject,  in  spite  of  extensive 
lesions. 

When  Andral  published  a  collection  of  ninety-three  cases 
in  which  well-marked  lesions  of  the  cerebellum  were  found 
after  death,  and  announced  that  only  one  sustained  the  view 
that  the  cerebellum  governed  coordination  of  movement, 
physiologists  were  startled  and  made  to  doubt  the  positive- 
ness  of  their  own  conclusions.  These  cases  are,  however, 
carefully  analyzed  by  Flint,  who  enters  into  a  lengthy  argu- 
ment to  prove  that  the  cases  cited  do  not  warrant  the  conclu- 
sion of  their  compiler.  Nothnagel  published  in  1878  the 
results  of  his  analysis  of  more  than  two  hundred  and  fifty 
cases  of  cerebellar  disease.  He  is  inclined  to  admit  the  exist- 
ence of  cerebellar  ataxia  (which  he  describes  as  a  perversion 
of  equilibrium  resembling  alcoholic  intoxication)  as  charac- 
teristic of  cerebellar  disease  ;  but  he  thinks  that  the  superior 
vermiform  process  is  especially  liable  to  produce  it,  if  exten- 
sively affected.  In  the  majority  of  instances  the  upper  ex- 
tremities remain  free  from  incoordination.  Subjects  in  whom 
cerebellar  ataxia  is  well  marked  stand,  as  a  rule,  with  their 
feet  well  apart,  in  order,  as  it  were,  to  increase  their  base  of 
support ;  they  sway  from  side  to  side  and  titubate  ;  the  toes 
are  seen  to  be  in  active  motion  if  the  patient  stands  bare- 
footed ;  in  walking,  the  body  sways  and  the  heel  and  ball  of 
the  foot  are  brought  into  contact  with  the  ground  irregularly ; 
the  ataxic  symptoms  may  and  may  not  be  increased  by  clos- 
ing the  eyes  ;  in  the  recumbent  posture  all  these  ataxic  mani- 
festations entirely  disappear. 

The  tentorium  cerebelli,  which  seiTes  to  separate  the  cere- 
bellum from  the  posterior  cerebral  lobes,  and  which  in  some 
animals  is  a  partition  of  bone,  ai)pears  to  have  a  clinical  bear- 
ing upon  the  development  of  lesions  of  the  cerebellum,  since 
it  seems  to  favor  their  growth  in  a  forward  and  downward 
direction.  It  is  important  for  you  to  bear  this  in  mind  when 
the  effects  of  focal  lesions  of  this  ganglion  are  under  con- 


SYMPTOMS  OF  CEREBELLAR  LESION'S.  235- 

sideration  ;  as  well  as  the  fact  that  an  experimental  or  patho- 
logical lesion  seldom,  if  ever,  involves  all  the  numerous  nerve- 
tracts  and  centers  which  exist  within  this  ganglion,  and  have 
different  peripheral  connections. 

By  recalling  the  important  connections  of  the  cerebellum 
with  other  parts  of  the  brain  and  the  spinal  nerve-tracts,  by 
means  of  its  three  crura,  and  bearing  in  mind  also  that  the 
third,  fourth,  fifth,  acoustic,  and  pneumogastric  nerves  may 
possibly  have  direct  sources  of  origin  within  its  substance  (the 
proof  of  a  relation  with  all  of  which,  however,  is  still  some- 
what unsatisfactory'),  you  can  readily  understand  that  the 
symptomatology  of  cerebellar  lesions  must,  of  necessity,  be 
peculiarly  involved  and  complex.  The  important  organs 
which  underlie  the  cerebellum  (the  corpora  quadrigemina,  the 
tegmentum  cruris,  and  the  medulla  oblongata)  are  liable,  fur- 
thermore, to  be  simultaneously  affected,  either  by  pressure  or 
the  extension  of  the  disease  to  these  parts.  Within  the  first 
of  these  we  probably  have  centers  which  govern  the  move- 
ments of  the  eyeball  (Adamuck) ;  in  the  second,  a  vaso-motor 
center,  and  possibly  one  which  presides  over  convulsive  move- 
ments, (?)  are  believed  by  some  authorities  to  exist ;  tn  the 
third  we  find  the  olivary  bodies,  which  are  connected  with  the 
cerebellum,  and  the  various  nuclei  of  origin  of  important 
cranial  nerves. 

We  are  apparently  justified,  on  anatomical  grounds,  in 
attributing  the  disturbances  of  msion  which  are  so  often  ob- 
served in  connection  with  lesions  of  the  cerebellum  to  pressure 
upon  the  geniculate  bodies,  the  corpora  quadrigemina,  or  the 
fibers  or  nuclei  of  origin  of  the  third,  fourth,  or  sixth  nerves. 
On  similar  grounds,  the  attacks  of  nausea^  vomiting,  cardiac 
disturbances,  and  sudden  death  sometimes  encountered  may 
be  attributed  to  the  pressure  of  cerebellar  lesions  upon  the 
nuclei  of  origin  of  the  vagus  nerve  within  the  floor  of  the 
fourth  ventricle,  resulting  in  either  irritation  or  complete 
paralysis  of  that  nerve.     The  convulsive  attacks,  which  are 

^  The  connection  of  the  auditory  nerve  with  the  cerebellum  is  now  quite  generally 
accepted  by  neurologists. 


236  ^^^  BR  A  IK 

occasionally  observed  in  connection  witli  cerebellar  lesions, 
may  perhaps  be  explained  by  pressure  upon  the  convulsive 
center  of  the  tegmentum  cruris;  and  the  development  of 
hemiplegia  of  an  imperfect  type,  or  of  general  paralysis, 
both  of  which  have  been  reported  as  occurring  from  cere- 
bellar disease,  may  be  explained  by  a  similar  effect  upon  the 
direct  motor  tract  of  the  cerebral  projection  system. 

In  direct  antagonism  to  the  results  of  Flourens's  experi- 
ments, lesions  of  the  cerebellum  of  the  human  race  seem  to 
be  often  associated  with  pain,  which  predominates  in  the  oc- 
cipital region.  In  fact,  the  diagnosis  of  cerebellar  disease  is 
made  chiefly  on  the  predominant  occipital  pain  (Brown- 
Sequard,  Seguin,  and  others),  with  titubation  and  other  pe- 
culiarities observed  during  the  erect  attitude  of  the  patient. 
Exclusion  of  disease  in  adjoining  regions  must,  however, 
always  be  made  by  the  absence  of  symptoms  before  making 
a  positive  diagnosis,  because  occipital  pain  and  titubation 
may  both  be  often  wanting,  and  the  so-called  '*  ataxic  symp- 
toms," when  present,  do  not  exist  in  the  marked  degree  com- 
monly met  with  in  posterior  spinal  sclerosis.  It  is  uncom- 
mon to  find  true  ataxic  jerking ;  and  choreic  movements  and 
tremor  are  usually  absent.  The  want  of  harmony  between 
antagonistic  groups  of  muscles  is  also  wanting. 

An  attempt  has  been  made  to  connect  the  cerebellum  with 
the  generative  function,  but  physiological  experiment  has 
apparently  demonstrated  its  fallacy.  A  rooster,  in  whom  the 
cerebellum  had  been  removed,  attempted  to  mount  a  hen 
eight  months  afterward,  and  failed  apparently  only  on  ac- 
count of  the  lack  of  power  to  coordinate  his  muscles  (Flou- 
rens).  There  seems  to  be  no  well- authenticated  instance 
where  the  sexual  instinct  has  been  destroyed  in  animals  by 
removal  of  the  cerebellum.  Leuret  found  that  the  cerebellum 
was  even  larger  in  geldings  than  in  stallions  or  mares.  Among 
the  numerous  cases  of  disease  of  this  ganglion  to  which  we 
have  referred,  some  suffered  from  a  marked  excitation  of  the 
sexual  apparatus,  while  others  had  a  well-marked  atrophy  of 
the  genital  organs  and  impotency.     There  are  many  physio- 


SYMPTOMS  OF  CEREBELLAR  LESION'S  237 

logical  as  well  as  pathological  facts  which  tend  to  refute  the 
idea  that  the  cerebellum  is  the  seat  of  sexual  instinct,  and  to 
locate  it  in  the  lumbar  region  of  the  spinal  cord  ;  still  it  can- 
not be  denied  that  numerous  cases,  on  the  other  hand,  seem 
to  point  to  some  connection  between  the  cerebellum  and  that 
center,  or  the  organs  of  generation,  in  the  human  subject. 

When  the  corpus  striatum  was  discussed,  it  was  stated  that 
the  superior  peduncles  of  the  cerebellum  could  perhaps  be 
traced  to  the  so-called  "  yellow  nucleus"  of  the  caudate  por- 
tion of  that  ganglion.  Luys  considers  that  by  means  of  these 
fibers  the  cerebellum  is  thus  enabled  to  constantly  reenforce 
the  cells  of  the  corpus  striatum  when  they  become  exhausted, 
thus  enabling  them  to  exert  their  modifying  effects  upon  all 
the  motor  impulses  arising  in  the  cerebral  cortex  which  are 
forced  to  pass  through  them,  as  well  as  to  manifest  a  peculiar 
automatism  which  the  cells  of  the  basal  ganglia  seem  to  pos- 
sess. This  theory  of  Luys  does  not  differ  markedly  from  that 
advanced  by  Mitchell,  viz.,  that  the  cerebellum  serves  as  a 
storehouse  of  nerve  force,  which  may  be  drawn  by  means  of 
any  of  its  peduncles  when  emergencies  arise  to  demand  it. 
Some  interesting  physiological  experiments  have  been  made, 
which  seem  to  point  to  some  intimate  association  between  the 
cerebellum  and  the  basal  ganglia.  We  know  that  section  of 
the  middle  peduncle  of  the  cerebellum  almost  invariably  gives 
rise  to  a  peculiar  "  forced  movement,"  the  animal  rolling  rap- 
idly round  its  own  longitudinal  axis,  the  rotation  being  com- 
monly toward  the  side  operated  upon.'  This  is  accompanied 
by  a  peculiar  dancing  and  oscillation  of  the  eyeballs,  termed 
"nystagmus."  Now,  Purkinje  observed  long  ago  that  elec- 
tric currents  sent  through  the  head  from  ear  to  ear  produced 
the  same  movements  of  the  eyeballs,  and  a  tendency  toward 
the  forced  movement  of  rotation.  The  patient  leans  toward 
the  anode,  and  objects  spin  before  the  eyes  in  the  direction  of 
the  electric  current.  When  the  current  is  broken  the  objects 
revolve  in  an  opposite  direction,  and  the  patient  leans  toward 
the  cathode.     Hitzig  has  shown  that  neither  the  vertigo  nor 

'  Bechterew  has  lately  shown  that  section  of  the  olivary  bodies  has  the  same  effect, 
10 


THE  BRAIK 

the  movements  of  the  patient's  body  depend  upon  the  objects 
perceived  by  vision,  since  the  same  phenomena  were  witnessed 
in  blind  subjects  and  in  those  whose  eyes  were  closed.  He 
found  also  that  vertigo  could  be  excited  in  this  way  with  a 
current  too  feeble  to  excite  ocular  movements. 

These  remarkable  experiments  have  been  used  by  different 
authors  as  confirmatory  evidence  of  the  three  following  propo- 
sitions :  1.  That  the  symptoms  produced  indicated  an  ane- 
lectronic  and  catelectronic  state  of  the  respective  auditory 
nerves  ;  2.  That  the  cerebellar  structures  were  called  into 
action  by  the  current ;  3.  That  parts  of  the  cerebrum  were 
affected  by  the  current. 

The  experiments  of  Cyon  afforded  ground  for  the  first 
proposition,  since  he  found  that,  when  the  semicircular  canals 
of  the  ear  were  divided,  peculiar  "forced  movements"  and  a 
loss  of  coordination  were  produced.  The  symptoms  noticed 
in  auditory  vertigo  (Meniere's  disease)  are  strongly  in  accord 
with  these  experiments,  since  slight  defects  in  hearing  are 
accompanied  in  some  instances  by  alarming  vertigo,  vomit- 
ing, and  unconsciousness. 

The  second  proposition  seems  improbable,  because  the  seat 
of  the  electrodes  would  appear  to  be  too  far  removed  from  the 
cerebellum  to  directly  affect  it. 

The  third  proposition  is  based  upon  the  situation  of  the 
electrodes  and  the  fact  that  the  electric  current  may  be  sup- 
posed to  pass  in  the  most  direct  line  through  the  cerebral  sub- 
stance. It  is  possible  that  the  artificial  current  is  suificiently 
strong  to  arrest  in  its  passage  the  cerebellar  current  which 
constantly  flows  into  the  cells  of  the  caudate  nucleus  of  the 
corpus  striatum,  and  that  the  symptoms  of  vertigo  and  inco- 
ordination are  to  be  thus  explained. 

From  a  standpoint  of  our  present  knowledge,  the  cerebel- 
lum must  be  considered  as  the  "  terra  incognita  "  of  the  brain. 
The  clinical  evidence  is  discordant.  The  anatomical  connec- 
tions of  the  cerebellum  with  other  parts  of  the  nervous  system 
are  remarkable,  and  their  minute  structure  is,  as  yet,  imper- 
fectly understood.     The  region  overlapped  by  the  cerebellum 


SYMPTOMS  OF  CEREBELLAR  DISTURBANCE.  239 

is  interspersed  with  important  collections  of  gray  matter 
which  act  as  nuclei  of  origin  for  important  nerve  tracts,  so 
that  all  experiments  made  upon  the  cerebellum  itself,  or  its 
peduncles,  are  liable  to  cause  injury  to  some  of  the  neighbor- 
ing parts,  and  thus  to  yield  results  which  are  puzzling  and 
unreliable.  Conjecture  inevitably  forms  an  important  element 
in  all  of  the  theories  advanced  respecting  the  functions  of  the 
ganglion  itself,  or  of  certain  of  its  parts.  Nothnagel  claims 
to  have  demonstrated  that  mechanical  stimulation  of  the  sur- 
face of  the  cerebellum  will  give  rise  to  muscular  movement 
without  signs  of  pain  being  perceived.  He  found  that  these 
movements  developed  slowly,  appearing  first  on  the  side  oper- 
ated upon,  and  then  ceasing,  only  to  appear  upon  the  opposite 
side.  He  states  that  he  has  demonstrated  that  the  fifth,  facial, 
and  hypoglossal  nerves,  as  well  as  nerves  distributed  to  the 
trunk  and  extremities,  can  be  thus  called  into  action.  The 
same  observer  concludes  that  destruction  of  the  commissural 
fibers  of  the  cerebellum  alone  produces  incoordination  of 
movement.  Hitzig  and  Ferrier  believe  that  injuries  to  the 
lateral  lobe  produce  the  same  varieties  of  ''forced  move- 
ments "  as  are  noticed  after  section  of  the  middle  peduncle. 
Flourens  observed  that  injuries  to  the  anterior  or  posterior 
parts  of  the  median  process  caused  animals  to  fall  forward  or 
backward  respectively,  and  his  views  have  been  confirmed  by 
others.  Ferrier  found  that  stimulation  of  the  cerebellar  cor- 
tex by  the  interrupted  electric  current  produced  in  monkeys, 
cats,  and  dogs  movements  of  the  eyeballs,  with  associated 
movements  of  the  head,  limbs,  and  pupils.  Adamuck  pro- 
duced the  same  effects,  however,  by  stimulating  the  corpora 
quadrigemina.  Hitzig  refutes  the  view  that  Ferrier's  results 
were  due  to  an  escape  of  the  current,  by  claiming  to  have  pro- 
duced similar  effects  by  mechanical  irritation  of  the  cortex. 
Eckhard  has  brought  forward  facts  which  tend  to  show  that 
in  certain  parts  of  the  cerebellum  lesions  tend  to  produce  dia- 
betes or  simple  hydruria,  thus  resembling  the  effects  of  irri- 
tation of  the  medulla  in  the  region  of  the  floor  of  the  fourth 
ventricle. 


240  THE  BRAIK 


In  the  face  of  this  conflicting  mass  of  experimental  evi- 
dence, I  mention  now  one  of  the  most  plausible  and  attractive 
theories  respecting  the  relation  of  the  cerebellum  and  cere- 
brum to  muscular  contraction,  which  has  been  advocated  by 
Spencer  and  sustained  by  Hughlings- Jackson,  Koss,  and 
others.  It  is  believed  by  these  authors  that  all  continuous 
tonic  muscular  contraction  is  governed  by  the  cerebellum, 
and  the  alternate  or  clonic  muscular  contractions  by  the 
cerebrum,  in  so  far  as  they  are  required  to  maintain  a  posture 
or  produce  a  change  in  attitude.  In  all  efforts  to  maintain  an 
attitude  (one  assumed  as  the  result  of  some  cerebral  impres- 
sion received),  the  cerebellum  holds  the  muscular  apparatus 
in  its  proper  state  of  tonicity  ;  but  when  the  attitude  is  to  be 
changed,  for  any  possible  reason  of  which  the  cerebrum  is 
conscious,  the  proper  muscles  are  relaxed  and  others  thrown 
into  a  state  of  contraction  by  means  of  the  higher  ganglion. 
The  body  is  then  intrusted  to  the  influence  of  the  cerebellum 
if  the  attitude  is  to  be  again  maintained.  Thus  it  is  sug- 
gested that  the  cerebellum  be  considered  as  capable  of  auto- 
matic action,  but  still  as  a  subordinate  to  the  cerebrum,  which 
possesses  the  power  of  overcoming  it  in  one  of  two  ways: 
First,  by  increasing  the  supply  of  nerve  force  to  certain  sets 
of  cells,  then  under  the  influence  of  the  cerebellum,  and  thus 
altering  the  traction  upon  muscles ;  or,  second,  by  inhibiting 
or  totally  arresting  the  cerebellar  influx  to  the  antagonistic 
sets  of  muscles.  Both  are  designed,  according  to  this  view, 
to  act  either  automatically  or  in  unison,  but  the  cerebellum 
is  the  servant  of  the  cerebrum,  to  do  its  bidding  when  re- 
quired. 

It  will  be  at  once  perceived  that  this  theory  applies  to  the 
complex  physiological  acts  of  walking ;  the  prolonged  main- 
tenance of  any  given  posture ;  the  transfer  of  the  center  of 
gravity  ;  the  passive  state  of  groups  of  muscles  ;  and  many  of 
the  morbid  phenomena  observed  in  muscles,  as  the  result  of 
impairment  of  the  higher  nerve-centers.  It  will  be  impossible 
to  discuss  all  of  these  conditions  in  this  connection.  Hugh- 
lings- Jackson  and  Ross  have  covered  the  more  important 


DIAGNOSIS  OF  CEREBELLAR  LESION'S  241 

points  in  their  works.  If  we  form  onr  views-  of  the  physio- 
logical functions  of  the  cerebellum  purely  from  the  standpoint 
of  the  anatomical  connections  which  that  ganglion  is  known 
to  possess,  we  cannot  but  agree  with  Bechterew  in  some  of  the 
conclusions  which  he  has  lately  advanced.  This  author  be- 
lieves that  the  cerebellum  is  intimately  connected  with  three 
organs  which  tend  to  exert  an  influence  upon  equilibrium,  as 
follows :  First,  the  semicircular  canals^  connected  with  the 
organ  of  hearing  ;  second,  the  organ  of  sights  since  the  move- 
ments of  the  globe  of  the  eye,  and  possibly  the  sense  of  vision, 
may  be  traced  to  a  relation  with  the  gray  matter  in  the  floor 
of  the  third  ventricle,  and  subsequently  with  the  cerebellum  ; 
third,  the  olivary  gray  matter^  which  the  author  thinks  is 
probably  connected  with  the  organs  of  tactile  sensibility. 

The  views  of  this  author  have  been  in  part  anticipated  and 
sustained  by  Spitzka,  who,  in  an  admirable  article  published 
about  two  years  ago,  considered  the  cerebellum  as  the  center 
where  "impressions  of  touch  and  position  are  associated  with 
those  of  time  and  space,"  and  hence  the  seat  of  coordination 
of  the  most  delicate  forms  of  movements  ;  such  as  are  neces- 
sary, for  instance,  to  the  proper  adjustment  of  the  drum- 
membrane  of  the  ear  for  the  correct  appreciation  of  sounds, 
the  appreciation  of  time  and  rhythm,  and  the  finer  acts  of 
equilibrium.  In  filling  this  position,  the  latter  author  be- 
lieves that  the  cerebellum  is  subordinate  to  the  cerebrum,  to 
which  it  acts  as  an  ''informing  depot"  for  coordination, 
rather  than  as  a  distinct  center. 

DIAGN^OSTIC   SYMPTOMS   OF   LESIONS   OF  THE   CEREBELLUM. 

The  functional  attributes  of  this  ganglion  are  as  yet  im- 
perfectly determined,  and  the  effects  of  lesions  (tumors, 
haemorrhage,  softening,  and  sclerosis)  which  involve  its  dif- 
ferent regions  vary  with  their  seat.  The  following  deductions 
are  based  chiefly  upon  those  of  N'othnagel,  who  has  devoted 
special  attention  to  diseases  of  this  ganglion,  and  those  of 
Seguin,  who  has  lately  contributed  a  digest  of  several  cases 
of  cerebellar  disease : 


242  THE  BRAIN. 

Lesions  of  one  of  tlie  cerebellar  hemispheres  are  often 
incapable  of  diagnosis,  especially  if  only  one  hemisphere  be 
involved. 

Lesions  of  the  vermiform  process  are  generally  attended 
with  symptoms  of  a  more  decided  character. 

Incoordination  of  movement^  an  intense  vertigo  (identical 
with  that  of  Meniere's  disease),  and  a  "  titubating  gait,''  are 
the  more  common  effects  of  cerebellar  lesions  ;  but  these  are 
not  in  themselves  pathognomonic  of  cerebellar  disease,  because 
they  may  be  produced  by  lesions  of  other  parts  of  the  brain. 
The  consideration  of  all  the  morbid  phenomena  of  each  case 
(both  of  a  positive  and  negative  character)  is  required  to 
render  the  diagnosis  certain. 

A  staggering  gait  is  especially  liable  to  be  developed  in 
case  the  "worm"  of  the  cerebellum  is  directly  involved,  or  is 
pressed  upon  by  lesions  of  adjacent  parts.  It  only  exists 
when  the  subject  is  in  the  upright  posture,  and  the  ataxic 
symptoms  rarely  affect  the  delicate  movements  of  the  fin- 
gers. 

Gastric  crises  (chiefly  exhibited  by  persistent  vomiting) 
are  a  diagnostic  feature  of  lesions  of  the  cerebellum  in  many 
cases.  When  destructive  lesions  of  the  cerebellum  exist, 
vomiting  is  less  frequently  observed  than  when  that  ganglion 
is  encroached  upon  by  lesions  of  other  j)arts. 

Atrophy  of  the  cerebellum  has  been  observed  to  produce 
imperfections  of  speech  (anartheia).  The  difficulty  seems 
to  be  confined  exclusively  to  the  motor  apparatus.  The  mem- 
ory of  words  is  not  disturbed. 

Pain  in  the  occipital  region  is  often  present  in  cerebellar 
disease. 

The  organ  of  vision  may  be  affected.  Occasionally,  the 
eyes  may  exhibit  incoordination  of  movement  and  nystag- 
mus ;  and  also  the  evidences  of  choked  disk,  amblyopia,  and 
amaurosis. 

Hcemorrhage  into  the  cerebellum  is  sometimes  associated 
with  a  loss  of  facial  expression,  due  to  a  slight  paresis.  The 
patient  may  also  exhibit  a  tendency  to  assume  one  position, 


THE  PITUITARY  BODY.  243 

and  to  return  to  it  when  moved  by  the  attendants.  Should 
hemiplegia  occur,  it  indicates  that  the  lesion  exerts  pressure - 
effects  upon  the  pyramidal  tracts,  either  in  the  crus,  pons,  or 
medulla. 

Irregularity  of  the  hearts  action^  which  is  sometimes  ob- 
served in  connection  with  a  cerebellar  lesion,  indicates  a 
pressure  upon  the  cardio-inhibitory  center  of  the  medulla. 

Abnormal  mental  symptoms  are  generally  absent  in  con- 
nection with  cerebellar  lesions.  When  atrophy  of  the  organ 
is  present,  or  when  other  parts  of  the  brain  are  diseased  simul- 
taneously with  the  cerebellum,  mental  derangements  may  be 
observed. 

When  the  middle  crura  of  the  cerebellum  (those  going  to 
the  pons)  are  affected  by  lesions  which  create  irritation, 
rotary  movements  of  the  body  and  a  lateral  deflection  of  the 
head  and  eyes  may  be  developed.  As  a  rule,  these  rotary 
movements  are  toward  the  healthy  side  ;  feut  this  is  not  in- 
variably the  case,  as  they  sometimes  are  toward  the  side  upon 
which  the  lesion  is  situated.  It  is  a  curious  fact  that  most  of 
the  effects  of  cerebellar  lesions  are  attributable  to  a  greater  or 
less  extent  to  irritation  of  the  crura. 

Lesions  of  the  superior  peduncle  of  the  cerebellum  are 
liable  to  induce  paralysis  of  the  motor-oculi  nerve,  as  shown 
by  the  development  of  ptosis,  external  strabismus,  and  dilata- 
tion of  the  pupil.  Hemianesthesia  and  more  or  less  ataxia 
may  be  induced  by  pressure  upon  the  tegmentum  and  the 
fillet  tract  (lemniscus). 


THE  PITUITARY  BODY. 

That  portion  of  the  brain  which  lies  in  the  sella  turcica  of 
the  sphenoid  bone  is  called  the  pituitary  body  or  the  hypo- 
physis cerebri.  It  was  formerly  called  the  pituitary  gland, 
because  it  was  supposed  to  discharge  '^pituita"  into  the  nos- 
trils.    It  is  diagrammatically  shown  in  Fig.  37. 

It  is  a  smaU,  reddish  mass,  which  consists  of  two  lobes,  of 
which  the  anterior  is  the  larger  and  embraces  the  posterior. 


244  THE  BRAIN. 

The  anterior  lobe  is  darker  in  color  than  the  posterior,  and, 
in  the  adult,  consists  of  a  lar^e  number  of  slightly  convoluted 
tubules  or  alveoli,  which  are  lined  with  epithelium.  Some- 
times a  colloid  substance  is  found  within  them.  It  is  joined 
to  the  posterior  lobes  in  mammals  only. 

The  posterior  lobe  is  developed  as  a  hollow  projection  from 
the  portion  of  the  cavity  of  the  embryonic  brain  which  is 
destined  to  constitute  the  cavity  of  the  third  ventricle.  It 
remains  small  and  undeveloped  in  the  higher  vertebrates 
but  becomes  transformed  into  an  integral  part  of  the  brain 
in  the  lower  vertebrates  through  the  formation  of  nerve 
cells  and  nerve  fibers  within  it.  Occasionally,  the  cavity 
whigh  originally  existed  in  its  substance  remains  unoblit- 
erated. 

The  function  of  the  pituitary  body  is  unknown.  In  its 
microscopic  structure,  the  anterior  lobe  closely  resembles 
that  of  the  thyroid  body. 


THE  MEDULLA  OBLONGATA  AND  PONS  VAROLII. 

The  medulla  oblongata  is  received  anteriorly  (ventrad)  into 
a  groove  on  the  basilar  process  of  the  occipital  bone,  and  pos- 
teriorly (dorsad)  into  a  fossa  between  the  cerebellar  hemi- 
spheres. From  its  sides,  the  seventh,  eighth,  ninth,  tenth, 
eleventh,  and  twelfth  cranial  nerves  escape. 

Its  form  has  been  compared  to  an  "irregularly  truncated 
cone."  It  is  expanded  both  laterally  and  antero-posteriorly 
at  its  upper  portion,  and  measures  about  one  inch  in  length, 
three  quarters  of  an  inch  in  its  greatest  breadth,  and  slightly 
less  in  its  dorso-ventral  plane. 

The  anterior  median  fissure  of  the  spinal  cord  is  pro- 
longed upward  (cephalad)  throughout  the  whole  extent  of  the 
medulla,  and  terminates  (at  the  junction  of  the  medulla  with 
the  pons  Varolii)  in  a  deep  recess,  called  the  '^ foramen  ccecum 
of  Vicq  d'Azyr:'  Some  of  the  decussating  bundles  of  the 
pyramids  partially  interrupt  this  fissure. 

The  posterior  median  fissure  of  the  spinal  cord  is  also 


THE  MEDULLA    OBLONGATA  AND  PONS. 


245 


res- 


continued  upward  (cephalad)  into  the  medulla,  as  far  as  the 
lower  angle  of  the  fourth  ventricle,  where  the  so-called 
tiform  bodies  "  diverge. 

We  owe  to  Stilling,  Van  der 
Kolk,  Turck,  Meynert,  Clarke, 
Flechsig,  Krause,  Spitzka,  Laura, 
Aeby,  Roller,  Starr,  and  others 
who  have  devoted  special  study 
to  the  architecture  of  the  me- 
dulla, the  limited  knowledge  of 
this  complicated  piece  of  mech- 
anism we  now  possess.  Within 
this  ganglion  we  find  numerous 
collections  of  gray  matter  in  ad- 
dition to  well-defined  nerve  tracts. 
Some  of  these  gray  masses  are 
analogous  to,  and  probably  direct 
continuations  of,  distinct  areas  of 
the  spinal  gray  substance.  On 
the  other  hand,  we  are  forced  to 
admit  the  existence  of  other  nodal 
masses,  which  are  structurally  in- 
dependent of  any  relationship  to 
the  cord.  Some  well-defined  tracts 
of  nerve  fibers  within  the  cere- 
brum and  spinal  cord  find  their 
end  in  the  gray  masses  of  the 
medulla  and  pons ; '   while  other 


Fig.  50. — Anterior  view  of  the  me- 
dulla oblongata.     (Sappey.) 


^  In  connection  with  the  gray  substance  of 
the  pons,  the  late  researches  of  Flechsig  have 
shed  some  light  upon  the  relative  development 
of  different  nerve  tracts,  and  in  this  way  helped 
to  interpret  some  points  in  dispute  respecting 
their  distribution.  This  author  draws  the  fol- 
lowing conclusions  : 

1.  A  tract  of  nerve  fibers  passes  from  the 
frontal  lobe  of  the  cerebrum,  through  the  ante- 
rior division  of  the  internal  capsule,  and  the 
inner  two  fifths  of  the  crus  cerebri,  to  the  gray 
nuclei  in  the  antero-median  gray  matter  of  the 


1,  infundibulum ;  2,  tuber  cinercum  ; 
3,  corpora  albicantia ;  4,  cere- 
bral peduncle ;  5,  tuber  annu- 
lare; 6,  origin  of  the  middle 
peduncle  of  the  cerebellum ;  V, 
anterior  pyramids  of  the  medul- 
la oblongata;  8,  decussation  of 
the  anterior  pyramids  ;  9,  oliva- 
ry bodies ;  10,  restiform  bodies; 
11,  ardform,  fibers ;  12,  upper 
extremity  of  the  spinal   cord; 

13,  ligamentum   denticulatum  ; 

14,  14,  dura  mater  of  the  cord ; 

15,  optic  tracts;   16,  chiasm  of 
•   the  optic  nerves ;  IV,  motor  ocu- 

li  communis ;  18,  patheticus ;  19, 
fifth  nerve;  20,  motor  oculi 
extemus;  21,  facial  nerve;  22, 
auditory  nerve;  23,  nerve  of 
Wrisberg;  24,  glosso-pharynge- 
al  nerve ;  25,  pneumogastric ; 
26,  26,  spinal  accessory;  2*7, 
sublingual  nerve;  28,  29,  30, 
cervical  nerves. 


246  TEE  BRAIN, 

nerve  tracts  begin  in  these  gray  masses  and  are  either  pro- 
longed to  other  parts  of  the  brain,  or  leave  the  substance  of 
the  medulla  as  cranial  nerves,  possessing  various  functions. 

The  term  ^'medulla  oblongata,"  as  first  employed*  by 
Yieussens  and  Willis,  included  both  the  crura  cerebri  and 
the  pons  Varolii,  in  addition  to  the  ganglion,  to  which  the 
term  is  now  restricted  by  more  modern  authors.  It  is  used 
here  to  include  only  the  collection  of  nerve  tracts  and  gray 
masses  situated  between  the  pons  and  the  spinal  cord. 

The  medulla  has  been  subdivided  by  Krause  into  three 
portions,  whose  limits  are  as  follows :  The  inferior  ^portion 
extends  from  the  plane  of  the  first  cervical  nerve  to  the  lower 
border  of  the  olive  ;  the  middle  portion  includes  that  portion 
of  the  medulla  between  the  upper  and  lower  borders  of  the 
olive  ;  the  superior  portion  extends  from  the  upper  border  of 
the  olive  to  the  plane  intersecting  the  middle  of  the  floor  of 
the  fourth  ventricle.  Sections  of  the  inferior  and  middle  por- 
tions exhibit  the  central  canal  more  or  less  modified,  and 
those  of  the  superior  portion  show  the  ventriclilar  floor. 

The  line  of  origin  of  the  anterior  roots  of  the  spinal  nerves 
is  not  marked  by  a  distinct  furrow  in  the  spinal  cord  ;  but  in 
the  medulla  a  well-marked  longitudinal  groove  (which  extends 
as  far  as  the  lower  border  of  the  pons)  indicates  the  direct 
continuation  of  that  line.    This  groove  is  partially  obliterated 

pons.  This  tract  of  fibers  is  apparently  prolonged  (after  traversing  this  gray  mass)  to 
the  lateral  and  posterior  portions  of  the  cerebellum  ;  hence,  the  gray  substance  of  the 
pons  must  be  regarded  as  interpolated  in  a  tract  which  serves  to  unite  the  cerebellum 
with  the  frontal  lobes  chiefly,  but  not  exclusively,  of  the  opposed  cerebral  hemisphere. 

2.  The  postero-median  nuclei  of  the  gray  substance  of  the  pons  is  similarly  connected 
with  a  tract  of  fibers  that  joins  the  cerebellum  with  the  cortex  of  the  temporo-occipital 
region  of  the  cerebrum.  It  never  develops  when  the  cerebellum  is  wanting,  and  is  not 
clothed  with  myeline  until  some  months  after  birth.  The  course  of  this  tract  seems  to 
be  (1)  through  the  external  one  fifth  of  the  crus;  (2)  through  the  internal  capsule;  (3) 
along  the  base  of  the  lenticular  nucleus  of  the  corpus  striatum ;  and,  (4)  outward  to  the 
cortex.  The  late  development  of  these  fibers  apparently  disproves  any  connection  be- 
tween them  and  the  sense  of  hearing  or  of  the  tactile  sense. 

3.  The  caudate  and  lenticular  nuclei  of  the  corpus  striatum  are  connected  with  the 
nuclei  of  the  gray  substance  of  the  pons  by  means  of  fibers  that  pass  downward  through 
the  median  bundles  of  the  crus  to  the  substantia  nigra  and  the  nuclei  of  the  pons.  The 
fibers  of  this  tract  are  connected  with   the  cerebellum,  after  traversing  these  gray 


GRAY  MATTER   OF  MEDULLA    OBLONGATA.  247 

below  the  olivary  body  by  transverse  fibers  ;  above  this  point 
it  separates  the  olivary  body  from  the  pyramid. 

Out  of  this  groove  the  roots  of  the  hypoglossal  nerve  leave 
the  substance  of  the  medulla  ;  they  may  therefore  be  consid- 
ered as  analogous  to  the  anterior  roots  of  the  spinal  nerves 
below.  This  analogy  apparently  holds  good  in  respect  also 
to  the  area  of  gray  substance  within  the  medulla  from  which 
the  roots  of  this  nerve  appear  to  spring  ;  although  Spitzka  is 
led  to  believe  that  the  gelatinous  substance  anterior  to  the 
central  canal  of  the  spinal  cord  is  more  directly  connected 
with  its  formation. 

The  line  of  attachment  of  the  posterior  or  sensory  roots 
of  the  spinal  cord  is  prolonged  upon  the  surface  of  the  medul- 
la as  a  series  of  bundles  which  help  to  form  the  spinal  acces- 
sory nerve.  These  are  seen  to  approach  the  posterior  roots  of 
the  spinal  nerves  in  the  cervical  region,  and  to  swing  into  a 
direct  line  of  continuation  with  them  above  the  level  of  the 
foramen  magnum.  At  a  higher  level  of  the  medulla  the  vagus 
nerve  roots  spring  from  the  same  line,  and  still  higher  up  the 
roots  of  the  glosso-pharyngeal  nerve.  Assuming,  therefore, 
that  these  nerves  escape  from  regions  in  the  medulla  that  are 
analogous  to  those  associated  in  the  cord  with  the  posterior 
roots  of  the  spinal  nerves,  we  are  naturally  led  to  infer  that 
the  fibers  of  origin  of  these  nerves  are  probably  connected 
with  masses  of  gray  substance  within  the  medulla  which  are 
structurally  related  to  the  posterior  horns  of  the  spinal  gray 
matter.  This  is  apparently  the  fact,  as  subsequent  pages  will 
help  to  demonstrate. 

The  changes  which  occur  during  the  transition  state  (in 
which  the  spinal  cord  is  so  altered  in  its  construction  as  to 
accommodate  itself  to  the  requirements  of  the  medulla)  may 
be  simplified  to  the  mind  of  some  readers  by  an  illustration 
employed  by  Quain,  which  I  quote.  He  says  :  "The  opening 
up  of  the  central  canal  and  separation  of  the  lips  of  the  pos- 
terior median  fissure  bring  the  gray  matter  to  the  surface  of 
the  fourth  ventricle,  while  the  posterior  cornua  are  coinci- 
dently  shifted  to  the  side,  much  in  the  same  way  as  it  would 


243  THE  BRAIN. 

be  if  a  median  incision  were  made  from  the  posterior  surface 
of  the  spinal  cord  into  the  central  canal,  and  the  two  lateral 
halves  were  then  turned  outward,  so  that  the  sides  of  the 
posterior  median  fissure  became  the  posterior  surface  of  the 
cord." 

The  anatomical  construction  of  the  medulla  and  pons  is 
particularly  difficult  of  comprehension,  chiefly  because  the 


Pig.  61. — Anterior  view  of  the  medvlla  and  pons,  designed  to  show  some  of  the  relations 
of  surrotmding  parts  and  the  apparent  origin  of  the  cranial  nerves.  (From  a  sketch 
by  the  author.) 

The  cranial  nerves  arc  indicated  by  numerals.  G,  ganglion  of  Gasscr;  P,  pons  Varolii; 
C,  cerebellum ;  F,  flocculus;  11,  hypophesis  cerebri,  or  the  pituitary  body,  behind 
which  two  rounded  eminences,  the  corpora  albicantia,  are  seen. 

fibers  which  compose  the  motor  and  sensory  tracts  of  the 
cerebrum  are  more  or  less  intermingled  with  masses  of  gray 
matter  (some  of  which  have  not  been  as  yet  referred  to),  and 
greatly  altered  in  their  relative  positions  to  each  other  when 
compared  with  those  of  the  cms  cerebri  above  or  the  spinal 
cord  below. 


GRAY  MATTER   OF  MEDULLA    OBLON'GATA.  249 

It  will  facilitate  description  to  consider  separately  the 
gray  and  the  white  matter  of  the  medulla  and  pons. 

THE    GRAY    MATTER. 

The  gray  matter  of  the  medulla  and  pons  is  best  compre- 
hended by  tracing  from  below  upward  the  successive  changes 
which  the  gray  matter  of  the  spinal  cord  undergoes  from  the 
point  where  the  crossing  of  the  fibers  of  the  cerebral  motor 
tract  (Fig.  7)  occurs  throughout  the  entire  extent  of  the  me- 
dulla and  pons.  This  subject  naturally  divides  itself  into  the 
following  heads : 

(1)  A  hasty  survey  of  the  architecture  of  the  spinal  cord 
at  its  junction  with  the  medulla  oblongata,  noting  its  columns 
and  the  arrangement  of  its  gray  substance. 

(2)  The  gray  substance  of  the  medulla  at  its  lowest  part 
contrasted  with  that  of  the  spinal  cord. 

(3)  The  nuclei  of  origin  of  the  cranial  nerve  roots. 

(4)  The  method  of  continuation  of  the  anterior  horns  of 
the  cord  upward. 

(5)  The  continuation  upward  of  the  posterior  horns  of  the 
cord. 

(6)  The  continuation  upward  of  the  central  gray  column 
and  that  of  Clarke,  which  becomes  apparently  represented  in 
the  lower  planes  of  the  medulla. 

(7)  The  accessory  nuclei,  which  are  developed  with  the 
medulla  and  pons. 

(8)  The  superadded  gray  substance  of  the  medulla  and 
pons. 

The  diagram  introduced  (Fig.  52)  will,  it  is  hoped,  make 
clear  the  main  subdivisions  of  the  spinal  cord  (which  are  sim- 
ply enumerated  in  its  accompanying  text,  as  a  full  descrip- 
tion of  the  various  parts  is  reserved  for  the  section  which 
deals  exclusively  with  the  subject). 

We  are  now  prepared  to  study  a  section  of  the  medulla 
(made  at  its  point  of  junction  with  the  cord),  and  to  observe 
the  changes  in  the  gray  matter  which  are  produced  (1)  by 
modifications  in  the  relative  size  of  the  columns  depicted  in 


250 


THE  BRAIN. 


Fig.  52,  and  (2)  by  the  decussation  of  the  fibers  which  com- 
pose the  '^ crossed  pyramidal  columns"  of  the  cord,  shown  in 
the  diagram  (Fig.  53). 


Fig.  62. — A  diagram  to  show  tJie  more  important  subdivisions  of  the  spinal  cord. 
(Altered  from  Flechsig.) 

D,  anterior  horns ;  E,  posterior  horns ;  CI,  gray  columns  of  Clarke,  which  are  not  repre- 
sented in  the  lumbar  or  cervical  regions  of  the  cord.  They  are  introduced  here, 
however,  to  explain  some  subsequent  points  pertaining  to  the  architecture  of  the 
medulla ;  w.  c,  anterior  white  commissure ;  a.  g.  c,  anterior  gray  commissure  in  front 
of  the  central  canal ;  p.  g.  c,  posterior  gray  commissure :  K,  the  so-called  "  crossed 
pyramidal  columns"  (see  Fig.  46.);  G,  columns  of  TUrck,  or  the  so-called  "direct 
pyramidal  columns  " ;  H,  anterior  root  zones ;  C,  direct  cerebellar  columns ;  M,  col- 
umns of  Burdach,  or  the  so-called  "posteroexternal  columns";  N,  columns  of  GoU, 
or  the  so-called  "posterointernal  column";  S,  sensory  tract  of  lateral  colmnn, 
according  to  Gowers,  Ott,  and  others. 

In  this  section  we  perceive  that  the  continuation  of  the 
COLUMN  OF  GoLL,  or  the  so-called  '^fasciculus  gracilis, ^^  of 
each  side  is  increased  in  size  by  the  addition  of  a  mass  of  cells 
—the  ''clavate  nucleus  ^^— to  its  central  portion  (Fig.  53);  and 
that  the  column  of  Burdach,  or  the  so-called  "fasciculus 
cuneatus^^^  also  gains  a  collection  of  gray  matter — the  "tri- 
angular nucleus  " — at  a  slightly  higher  level. 

The  effect  of  this  increase  in  size  of  the  posterior  columns 
is  to  crowd  the  gelatinous  substance  of  the  posterior  horns  to 


THE  SPINO-MEDULLART  TRANSITIOK 


251 


either  side,  so  that  they  appear  near  to  the  lateral  borders  of 
the  section  (Figs.  53,  R,  and  54,  s  g). 

Again,  the  crossing  of  the  fibers  of  the  ''crossed  pyramidal 
column"  (Fig.   53)  cuts  off  a  portion  of  the  anterior  horns 
from    the    rest    of    the    gray 
substance,   and  also  tends  to  p.m.F^ 

tJirust  hacTcward  the  commis- 
sures, the  central  gray  column, 
and  the  central  canal. 

Other  important  modifica- 
tions occur,  in  addition  to 
these  changes  of  position  in 
the  component  parts  of  the 
gray  matter  (depicted  in  Fig. 
63),  as  a  result  of  the  giving 
off  of  fibers  (called  "arcuate 
fibers,"  because  of  the  semi- 
circular course  which  they 
pursue)  by  the  clavate  and 
triangular  nuclei  of  each  side. 

These  fibers  pass  to  the  oli- 
vary body  of  the  same  side 
(Fig.  54),  and  by  their  passage 
through  the  posterior  horns  of 
the  spinal  gray  matter  almost 

entirely  separate  the  substantia  gelatinosa  and  the  posterior 
horn  from  the  gray  substance  which  surrounds  the  central 
canal  of  the  cord. 

During  the  passage  of  these  arcuate  fibers,  they  become 
interlaced  with  the  fibers  of  the  crossed  pyramidal  columns. 
The  latter  decussate  at  this  level,  and  serve  to  detach  groups 
of  cells  from  the  anterior  horn,  which  are  thus  carried  into 
the  anterior  root  zones  (Fig.  53). 

Finally,  the  anterior  root  zones  of  Fig.  52  (now  the  lateral 
columns  of  the  medulla)  are  subdivided  by  the  arcuate  fibers 
of  the  triangular  and  clavate  nuclei,  and  the  arcuate  fibers 
of  the  inferior  peduncles  of  the  cerebellum  into  a  reticulated 


cL.m.f 


Fig.  53. — A  diajram  of  a  section  of  the 
medulla  at  tJie  middle  of  the  motor 
decussation. 

P,  pyramidal  fibers  undergoing  decussa- 
tion ;  a.  c,  anterior  cornu  ;  /.  c,  con- 
tinuation of  the  lateral  column  of  the 
spinal  cord ;  R.,  continuation  of  the 
substantia  gelatinosa  of  Rolando; 
p.  c,  continuation  of  the  posterior 
cornu ;  T.  n.,  triangular  nucleus ;  c.  w., 
clavate  nucleus  ;  p.  m.  /.,  posterior 
median  fissure;  a.  m.f,  anterior  me- 
dian fissure. 


252 


THE  BRAIN. 


formation— the  so-called  "-formatio  reticularis''— which  is 
thickly  studded  with  ganglion  cells  possessing  well-defined 
processes. 

The  gray  masses  found  in  the  reticular  field,  considered  in 
the  aggregate,  have  been  named  by  Spitzka  the  "ganglion 

reticular €.''  It  is  the  ganglion 
proper  of  the  medulla.  It  is  well 
developed  in  the  middle  olivary 
plane,  lying  to  the  lateral  side  of 
the  nucleus  for  the  hypoglossal 
nerve.  Spitzka  regards  it  as  the 
probable  center  "  for  those  rhyth- 
mical automatisms  which  (while 
under  the  control  of  the  higher 
centers)  involve  the  activity  of 
both  cranial  and  spinal  nerves." 
The  cells  of  this  structure  have 
more  than  one  axis-cylinder  pro- 
cess, according  to  the  same  au- 
thor, and  exhibit  apparent  con- 
nections in  all  possible  directions  ; 
chiefly,  however,  in  the  dorso- 
ventral  plane. 

Among  the  cells  of  the  reticu- 
lar formation  of  the  medulla  two 
well-defined  groups  exist,  which 
have  been  designated  as  the  '^  an- 
terior'' and  "posterior  nuclei  of 
the  lateral  column." 

The  nuclei  of  origin  of  the 
ninth,  tenth,  and  eleventh  cra- 
nial nerves  are  intimately  asso- 
ciated with  the  gray  matter  present  in  the  "reticular  field"  of 
the  medulla  (Fig.  59).  Krause,  Laura,  Meynert,  and  Spitzka 
differ  as  to  the  probable  connections  of  the  so-called  "nu- 
cleus ambiguous  "  of  Krause.  Meynert  associates  it  with  the 
tenth,  Laura  with   the  twelfth,  and  Spitzka  with  both  the 


a.m.f 


Fio.  54. — A  diagram  of  a  section  of 
the  medulla  at  a  sliglitly  higher 
level  than  in  the  preceding  figure. 

P,  pyramidal  fibers ;  N.  a,  arcifonn 
fibers ;  R,  raphae,  with  decussat- 
ing fibers  in  tlie  field;  O',  ac- 
cessory olive  ;  0,  olive  ;  /.  r., 
formatio  reticularis ;  c.  c,  cen- 
tral canal ;  n.  /.,  lateral  nucleus ; 
s.g,,  substantia  gelatinosa;  n.  c, 
nucleus  cuneatus ;  /.  c,  funicu- 
lus  cuneatus ;  /.  g.,  funiculus  gra- 
cilis; n.g.y  nucleus  of  the  same; 
n.  XI,  nucleus  of  the  eleventh 
nerve  (spinal  accessory) ;  «,  XII, 
same  of  the  hypoglossal  nerve; 
a.m./.,  anterior  median  fissure; 
p.  m.fy  posterior  median  fissure. 


NERVE  NUCLEI  IN  THE  MEDULLA.  253 

tenth  and  eleventh  cranial  nerves.  The  fibers  arising  from 
it  cross  the  raphse  of  the  medulla.  Spitzka  believes  that  it 
is  probably  connected  with  the  motor  apparatus  of  the 
larynx. 

The  ''ganglion  cells ^'  w\i\c\i  are  found  within  the  gray 
matter  of  the  spinal  cord  are  more  or  less  redistributed  within 
the  medulla,  after  they  have  been  separated  (at  its  lower  por- 
tion) by  the  fibers  of  the  crossed  pyramidal  columns  and  the 
arcuate  fibers  already  described.  Nuclei  of  special  nerve 
roots,  and  masses  whose  functions  are  not /yet  well  under- 
stood, are  thus  formed.  These  will  merit  subsequent  descrip- 
tion. 

The  nuclei  of  the  lateral  column  of  the  medulla^  which 
have  been  previously  mentioned,  appear  to  give  origin  to  a 
portion  of  the  fibers,  at  least,  of  the  spinal  accessory  nerve. 
Some  of  these  fibers  may  be  distinctly  traced  to  the  nerve  of 
the  opposite  side,  but  the  majority  wind  around  the  postero- 
lateral group  of  cells  to  join  the. nerve  of  the  same  side. 

As  we  ascend  the  medulla,  cross-sections  of  that  body  at 
different  levels  successively  reveal  the  nuclei  of  the  motor 
fibers  of  the  pneumogastric  and  glosso-pharyngeal  nerves ; 
Bext,  those  of  the  facial  nerve  ;  and,  later,  those  of  the  motor 
or  ascending  root  of  the  trigeminus. 

Nerve  Nuclei  in  the  Medulla. — By  referring  to  the  dia- 
gram which  is  now  introduced  (Fig.  5S)^  and  comparing  it 
with  the  one  which  follows,  the  reader  will  be  enabled  to 
form  a  tolerably  clear  conception  of  the  relative  situation 
and  extent  of  the  more  important  nuclei,  from  which  some 
of  the  cranial  nerve-roots  apparently  take  their  origin.  It 
can  be  more  readily  understood,  after  a  careful  study  of 
these  two  diagrams,  why  it  is  that  cross-sections  of  the  me- 
dulla and  pons  made  at  different  levels  present  such  wide 
variations  in  the  arrangement  of  the  gray  matter.  These  di- 
agrams will  help  also  to  render  such  sections  more  intelligible 
to  the  reader. 

Let  us  now  consider  somewhat  more  in  detail  the  points 
which  these  two  diagrams  present.  In  the  first  place,  it  will 
19 


254 


THE  BRAIN. 


be  seen  that  the  cranial  nerves  from  the  fifth  to  the  twelfth 
escape  from  the  pons  or  medulla  at  different  levels. 

Again,  it  will  be  observed  that  the  nuclei  of  origin  of  these 
nerves  are  situated  in  the  region  of  the  Jloor  of  the  fourth 


B.5. 


Fig.  65. —  Transparent  lateral  view  of  the  meduila,  shomng  the  relative  positions  of  the 
most  important  nuclei  ;  rigid  half  of  the  medulla,  seen  from  the  surface  of  section  ;  the 
parts  that  lie  closer  to  this  surface  are  deeper  shaded.     (After  Erb.) 

Py,  pyramidal  tract ;  Pj.  Kr.,  decussation  of  pyramids ;  0,  olivary  body ;  0.  s,  superior 
olivary  body;  5,  motor;  6',  middle  sensory;  6",  inferior  sensory  nucleus  of  tri- 
geminus; 6,  nucleus  of  abducens;  G. /,  genu  facialis;  7,  nucleus  facialis;  8, 
posterior  median  acoustic  nucleus;  9,  glosso-pharyngeal  nucleus;  10,  nucleus  of 
vagus;  11,  spinal  accessory  nucleus;  12,  hypoglossal  nucleus;  Kz.,  nucleus  of  the 
funiculus  gracilis ;  R,  5,  trigeminus  roots ;  those  of  the  R.  6,  abducens,  and  R.  7, 
facialis. 


yentricle,  and  that  they  are  so  distributed  (with  few  excep- 
tions) as  to  approximately  correspond  to  the  level  of  the 
superficial  origin  of  the  nerves  whose  roots  are  connected 
with  them. 

In  the  third  place,  it  will  be  seen  that  some  nerves  have 
more  than  one  nucleus  of  origin  in  the  medulla.  The  Jlfth 
has  one  motor  and  two  sensory  nuclei,  near  the  upper  part  of 


NERVE  NUCLEI  OF  THE  MEDULLA. 


255 


the  ventricle  ;  tlie  auditory  lias  four  nuclei,  the  anterior  and 
posterior  median,  and  the  anterior  and  posterior  lateral ; 
finally,  accessory  nuclei  have  been  discovered  for  the  facial, 
spinal  accessory,    and  hypoglossal  nerves.      These  are  not 


shown  in  the  diagrams. 


Thai 


Fig.  56. — Diagram  of  the  chief  tracts  in  the  medulla.     (After  Erb.)    The  formatio 
reticularis  is  represented  by  shading. 

01.,  olivary  body ;  V,  anterior ;  S,  lateral,  and  II,  posterior  spinal  funiculi ;  a,  pyramido- 
anterior  tract;  e?,  pyramido-lateral  tract;  Py.,  pyramidal  tract;  h^  remainder  of  ante- 
rior column ;  c,  remainder  of  lateral  column ;  e,  e,  cercbello-lateral  tract ;  /,  funiculis 
gracilis,  and  /',  nucleus  of  the  same ;  g.,  funiculus  cuneatus,  and  g',  nucleus  of  the 
same  ;  P.  c.  i.,  internal  fasciculus  of  the  pedunc.  cerebelli ;  P.  c.  e,,  external  fasciculus 
of  the  same ;  Cq.  F.,  tract  from  corp.  quadr.  to  format,  retic. ;  Cq.  0.,  the  same  to 
the  olivary  body ;  Thai.,  tract  from  the  thalamus  opticus. 


In  the  fourth  place,  it  should  be  noted  that  the  area  cov- 
ered by  the  nuclei  of  some  nerves  is  greatly  in  excess  of  that 
of  others.  The  trigeminus  nerve  has  one  sensory  nucleus 
(the  inferior)  which  extends  throughout  the  greater  part  of 
the  substance  of  the  pons  and  the  medulla  (Fig.  55,  Y") ; 


256  THE  BRAIN. 

while  the  "median  sensory "  and  the  " motor "  nuclei  of  the 
same  nerve  are  of  smaller  size.  The  ninth,  tenth,  eleventh, 
and  twelfth  cranial  nerves  have  longer  nuclei  than  the  sev- 
enth or  eighth. 

Having  now  grasped  the  general  situation  and  form  of  the 
nuclei  of  the  cranial  nerves  found  within  the  pons  and  me- 
dulla, it  seems  advisable  to  add  a  few  statements  respecting 
the  peculiarities  of  each,  which  may  aid  us  in  studying  the 
architecture  of  the  medulla  and  pons  by  cross-sections  of  the 
same. 

The  trigeminal  sensory  nuclei  are  analogous  in  some  re- 
spects to  the  posterior  horn  of  the  spinal  gray  matter,  since 
they  contain  only  small  ganglion  cells. 

The  nucleus  of  the  sixth  nerne  contains  large  cells '  (mo- 
tor), and  lies  at  the  junction  of  the  pons  and  medulla,  in  a 
groove  on  the  floor  of  the  fourth  ventricle,  near  the  fasciculus 
teretes. 

The  nucleus  of  the  facial  nerm  is  composed  of  large 
cells  (motor),  and  is  somewhat  lower  and  placed  more 
deeply  in  the  substance  of  the  medulla  than  that  of  the 
sixth. 

The  auditory  nerve  receives  fibers  from  four  independent 
nuclei  which  are  situated  in  the  region  of  the  broadest  por- 
tion of  the  fourth  ventricle. 

The  pneumo gastric  and  the  glosso-pharyngeal  nerms 
have  nuclei  of  origin  which  are  not  clearly  demarkated  from 
each  other,  although  the  nucleus  of  the  vagus  lies  deeper 
than  that  of  the  ninth  nerve. 

The  following  table  is  given  by  Spitzka  to  illustrate  the 
various  nuclei  of  the  medulla  that  appear  in  cross  sections 
made  at  different  altitudes  and  at  a  right  angle  to  the  long- 
axis  of  the  medulla. 

'  Spitzka  combats  the  view  that  a  differentiation  of  nerve  cells  in  rejrard  to  their 
function  can  be  made  on  their  dimensions  alone.  He  points  out  that  both  large  and 
multipolar  cells  may  have  a  sensory  function,  and  that  some  motor  cells  have  few  pro- 
cesses in  the  lower  vertebrates.  lie  states  that  a  gradual  transition  from  the  body  to  the 
processes  is  typical  of  motor  attributes,  and  that,  in  sensory  cells,  the  transition  is 
always  abrupt. 


NEEYE  NUCLEI  IN  THE  MEDULLA. 


257 


MOTOB    COLUMN 

BEPEE8ENTA. 

MIXED  COLUMN  REPBE8ENTA- 

Altitude  in  the 

TIVE. 

TIVE. 

Sensory  column 
representative. 

Subependymal. 

Insular. 

Subependymal, 

Insular. 

1 

Lower  roots 

Nucleus  of 

Nucleus 

Common 

Inferior  ac- 

Gelatinous 

of  12th  pair. 

12th  pair. 

pyr'midalis. 

vago-acces- 
sory  nucleus. 

cessory  nu- 
cleus. 

nucleus  of 
6th  pair. 

2 

Roots  of  9  th 

Barren. 

Absent. 

Nucleus  of 

Inferior  ac- 

Auditory nu- 

pair. 

9th  pair. 

cessory  nu- 
cleus. 

cleus. 

3 

Roots  of  6th 

Common  nu- 

i( 

Absent. 

Inferior  facial 

Auditory  nu- 

pair. 

cleus  of  6  th 
and  Yth  pairs. 

nucleus. 

cleus. 

4 

Exit  of  5th 
pair. 

Barren. 

u 

u 

Motor  nucleus 
of  5th  pair. 

Gelatinous 

nucleus  of 

5th  pair. 

5 

Valve  of 

Vieussens. 

Nucleus  of 
4th  pair. 

u 

Substantia 
ferruginea. 

Absent. 

Absent. 

6 

Root  of  3d 
pair. 

Nucleus  of 
3d  pair. 

(( 

Vesicular  cells 
of  most  ante- 
rior origin  of 
5th  pair. 

u 

(C 

The  areas  represented  by  Pn  and  G  in  Fig.  59  are  believed 
by  Spitzka  to  be  respectively  associated  with  the  fibers  of 
origin  of  the  pneumogastric  and  glosso-pharyngeal  nerves. 
He  considers  them,  therefore,  as  nuclei  for  ''visceral  innerva- 
tions" and  "gustatory  impressions."  He  is  led  to  this  con- 
clusion from  the  variations  observed  in  animals  as  regards 
the  development  of  these  nuclei,  and  the  preponderance  of 
these  cell-masses  in  the  planes  of  the  medulla  marked  by  the 
exit  of  the  rootlets  of  the  pneumogastric  and  glosso-pharyn- 
geal nerves. 

Some  authorities  give  to  the  pneumogastric  nerve  a  sec- 
ond nucleus  of  origin  in  the  substance  of  the  medullar  near 
the  olivary  body. 

The  hypoglossal  nucleus '  lies  close  to  and  in  front  of  the 
central  canal  of  the  cord,  as  low  as  the  level  of  the  decussa- 
tion of  the  pyramidal  fibers.  It  consists  of  large  branching 
nerve  cells,  similar  to  those  of  the  anterior  horns  of  the  spinal 
cord.     After  the  central  canal  has  opened  into  the  fourth 


^  The  nucleus  of  the  hjTJoglossal  nerve  is  considered  by  Spitzka  as  a  continuation  up- 
ward (cephalad)  of  the  gelatinous  gray  matter  lying  in  front  of  the  spinal  canal.  The 
anterior  horns  have  been  cut  off  (in  a  lower  plane  of  the  medulla)  by  the  decussation  of 
the  pyramidal  fibers. 


258 


THE  BRAIK 


ventricle,  this  nucleus  creates  a  prominence  close  to  tlie  me- 
dian line  of  the  ventricle,  slightly  above  the  point  of  the  cala- 
mus  scriptorius,  or  the  lower  angle  of  the  ventricle. 


R  Mill 


Fio.  5V. — A  cross-section  of  the  medulla  oblongata  on  a  level  with  the  superficial  origin 
of  the  auditory  nerve.     (Modified  from  Flechsig  by  Ross.) 

ip  ani  ep^  the  internal  and  external  divisions  of  the  inferior  peduncle  of  the  cerebellum  ; 
frs,  reticular  formation;  a,  arciform  fibers;  R.VIII,  root  of  eighth  nerve;  VIII  and 
VIII",  nuclei  of  same;  H,  hypoglossal  nucleus;  P,  pyramid;  jo,  accessory  portion 
of  same ;  po.  parolivary  body ;  np,  nucleus  of  the  pyramid ;  at,  ascending  root  of  fifth 
nerve ;  dc^  direct  cerebellar  tract ;  L,  posterior  longitudinal  bundle ;  0,  olivary  body ; 
«^,  substantia  gelatinosa. 

That  the  fibers  of  the  hypoglossal  nerve  are  prolonged  in 
some  way  upward  to  the  cerebral  cortex  seems  to  be  proven 
by  pathological  facts ;  although  they  have  not  yet  been  traced 
to  such  a  termination. 

The  medullary  portion  of  the  spinal  accessory  nerve  is 
destined  to  join  the  pneumogastric  nerve  after  its  exit  from 
the  skull,  while  the  spinal  portion  pursues  a  separate  course. 


MOTOR  NUCLEI  OF  MEDULLA.  259 

Its  nucleus  seems  to  be  a  prolongation  downward  of  the  nu- 
cleus of  the  vagus,  as  its  course  would  naturally  suggest. 

In  a  general  way,  it  may  be  stated  that  the  nuclei  of 
those  cranial  nerves  within  the  medulla  which  are  motor  in 
function  are  characterized  by  large  multipolar  cells,  while 
those  which  are  connected  with  the  sensory  nerve-roots  are 
composed  of  cells  of  smaller  size,  some  of  which  are  bipolar. 
In  some  respects  they  are  analogous  respectively  to  the  cells 
of  the  motor  or  kinesodic,  and  the  sensory  or  sesthesodic  re- 
gions of  the  spinal  gray  matter;  and  also  to  the  gray  sub- 
stance of  those  convolutions  of  the  cerebrum  which  preside 
over  similar  functions. 

Spitzka  has  called  attention  to  the  fact  that  the  evolution 
of  nervous  force  does  not  necessarily  imply  the  existence  of 
distinct  fibers  and  of  nerve  cells.  He  says:  ''In  the  lower 
forms  of  animal  life  a  uniform  blastema,  with  or  without 
nuclei,  and  entirely  devoid  of  nerve  cells,  is  frequently  all 
that  represents  a  ganglion ;  and  the  afferent  and  efferent 
strands  connected  with  such  a  simple  structure  are  composed 
of  an  infinite  number  of  granules  which  show  no  fibrillary 
arrangement." 

Again,  the  same  author  remarks:  "The  increased  perfec- 
tion of  the  nervous  system  is  marked  by  a  progressive  tend- 
ency to  isolation  of  the  conducting  strands." 

The  Upwaed  Continuation  of  the  Anterior  Horns 
OF  THE  Spinal  Gray  Substance. — We  have  already  men- 
tioned a  change  in  the  anterior  horns '  at  the  lower  part  of  the 
medulla  produced  by  the  decussation  of  the  motor  fibers, 
which  compose  the  so-called  "crossed  pyramidal  tracts." 
The  formation  of  two  groups  of  cells,  called  the  antero -lateral 
and  the  postero-lateral  groups,  here  takes  place.  Portions 
of  these  groups  are  carried  into  the  lateral  column  of  the 
medulla,  and  form  the  so-called  "anterior'"  and  ''posterior 

*  The  nucleus  of  the  pyramid  is  to  be  regarded  as  "  the  amputated  part  of  the  ante- 
rior horn "  of  the  corresponding  side  of  the  cord.  Spitzka  regards  it  as  an  accessory 
nucleus  to  the  hypoglossal  nerve,  classing  it  in  the  same  category  with  scattered  gray 
masses  from  the  lateral  system  higher  in  the  medulla.  He  believes  it  to  be  the  nucleus 
of  origin  of  those  fibers  which  supply  the  retractors  of  the  hyoidean  apparatus. 


THE  BRAIN. 


nuclei'^  of  that  column.  The  same  arrangement  appears  to 
be  carried  out  as  we  study  ascending  sections,  so  that  the 
spinal  accessory,  the  motor  fibers  of  the  pneumogastric  and 
glosso-pharyngeal,  the  facial,  and  the  motor  fibers  of  the  tri- 
geminus seem  to  spring  from  a  continuation  upward  of  the 
anterior  horns  of  the  spinal  gray  substance  in  its  lateral 
column. 

The  fibers  of  these  nerves  take,  as  a  rule,  an  extremely 
circuitous  course  before  escaping  from  the  medulla.  In  the 
case  of  the  facial  nerve,  a  peculiar  bend  in  its  fibers  of  origin 
has  been  named  the  "knee "  {^^ genu  nerm  facialis "). 

The  anterior  nucleus  of  the  lateral  column  of  the  medulla 
appears  to  cease  on  a  level  with  the  origin  of  the  facial  nerve, 
although  some  authors  believe  that  some  fibers  of  the  trigem- 
inus pass  from  it  in  an  upward  and  backward  direction. 


so 


UV 


Fig    58. — A  transverse  section  thrmigh  the  pons,  on  a  la)el  with  the  roots  of  the  sixth  and 
seventh  cranial  nerves  from  a  7iin€  months^  embryo.     (Modified  from  Erb  and  Ross.) 

The  right  half  represents  a  section  made  a  little  lower  than  the  left.  Tr,  transverse 
fibers  of  the  pons;  P,  pyramidal  fibers;  so,  superior  olivary  body;  L,  posterior  lon- 
gitudinal fasciculus;  <,  fasciculus  tcretes  (round  bundle) ;"UVI,  root  of  abducens; 
RVII,  root  of  facial ;  at,  ascondinji;  root  of  tri^'eininus ;  R,  round  bundle  ;  B.  pedun- 
cle of  cerebellum  ;  ar,  upward  prolongation  of  anterior  root  zone  of  the  spinal  cord  ; 
ale,  anterior  nucleus  of  facial  nerve ;  pic,  posterior  nucleus  of  same.  This  figure 
shows  well  the  interlacing  of  the  vertical  pyramidal  fibers  with  the  horizontal  (trans- 
verse) fibers  of  the  pons. 


THE  HYPOGLOSSAL  NUCLEUS.  261 

The  posterior  nucleus  of  the  lateral  column  of  the  me- 
dulla passes  behind  and  to  the  outside  of  the  nucleus  of  the 
abducens,  or  sixth  nerve,  before  joining  with  that  of  the  facial. 

The  development  of  the  olivary  body  within  the  substance 
of  the  medulla  tends  to  displace  the  whole  of  the  gray  matter 
backward,  until  the  posterior  gray  commissure  (Fig.  52)  dis- 
appears, and  the  central  canal  of  the  cord  opens  on  the  floor 
of  the  fourth  ventricle. 

The  nucleus  for  the  hypoglossal  nerve  roots  bears  a  strik- 
ing analogy,  as  regards  the  peculiar  distribution  of  its  cells, 
to  the  anterior  horns  of  the  spinal  gray  matter.  The  analogy 
is  heightened  furthermore  by  an  identical  method  of  develop- 
ment of  these  groups. ' 

At  the  upper  level  of  the  hypoglossal  nucleus  the  trans- 
verse fibers  of  the  pons  tend  to  separate  those  masses  of  gray 
matter,  which  are  probably  an  extension  upward  of  the  an- 
terior horns  of  the  spinal  gray  substance,  or  the  gelatinous 
substance  anterior  to  the  central  canal.  Hence  it  becomes 
extremely  difficult  to  trace  their  connections. 

In  the  larger  nucleus  of  the  hypoglossal  nerve,  Spitzka 
describes  a  collection  of  cells  whose  axis-cylinder  processes 
run  away  from  the  tract  of  the  hypoglossal  fibers,  rather  than 
toward  them.  These  cells  he  believes  to  be  associated  with 
the  eleventh  nerve  roots ;  and  he  thinks  that  an  associating 
mechanism  is  thus  established  between  the  movements  of  the 
tongue  and  of  the  vocal  cords,  as  is  required  in  phonation 
and  singing. 

There  are  some  grounds  for  the  belief  that  the  nucleus  for 
the  abducens,  or  sixth  nerve,  is  a  direct  continuation  of  the 
postero-lateral  group  of  cells  ;  because  the  fibers  of  the  facial 
nerve  wind  around  it  as  those  of  the  spinal  accessory  nerve 
do  around  the  postero-lateral  group  in  the  lower  part  of  the 
medulla. 

^Spitzka  makes  use  of  the  following  general  deduction  or  axiom:  "A  ganglion 
(center)  follows  in  development  the  development  of  the  periphery,  which  is  projected  in 
that  ganglion."  lie  advances  many  interesting  facts  in  support  of  this  law,  from  a  study 
of  the  comparative  anatomy  of  animals.  "  Journal  of  Nervous  and  Mental  Diseases," 
October,  1879,  p.  616. 


262 


THE  BRAIK 


The  nucleus  for  the  motor -oculi,  or  tliird  nerve ^  which 
has  been  partly  described  in  the  pages  that  treat  of  the 
cms  cerebri,  probably  belongs  to  a  group  of  cells  which  also 
constitutes  the  nucleus  of  the  abducens  nerve.  In  point  of 
fact,  it  is  reasonable  to  consider  the  nuclei  of  the  third, 
fourth,  and  sixth  cranial  nerves  as  parts  of  one  mass  of 


a.m.f 


Fio.  69. 


-A  transverse  section  of  tJie  medulla  {partly  schematic)  made  through  the  mid- 
dle of  the  olivary  body.     (Modified  from  Spitzka.) 

H,  and  h,  nuclei  of  origin  of  the  hypoglossal  nerve  (twelfth  cranial) ;  F.  R.,  reticular 
formation,  with  its  cell-masses ;  0,  olivary  body ;  P,  pyramid ;  a.  m.f.,  antero-me- 
dian  fissure ;  G  and  Pn,  masses  of  cells  probably  associated  respectively  with  the 
glosso-pharyngeal  and  pneumogastric  nerves ;  Va,  ascending  root  of  fifth  cranial 
nerve;  B,  restiform  column;  a./.,  arcuate  fibers  ;  F,  fibers  passing  through  the  inter- 
olivary  tract ;  e  and  d,  bundles  of  fibsrs  from  the  posterior  spinal  tracts,  cut  across 
on  their  way  to  the  inferior  cerebellar  peduncle  after  decussation  ;  T,  the  "  trineural 
fasciculus  "  of  Spitzka ;  "  solitary  "  or  "  round  "  bundle  of  other  authors.  Note  that 
the  solid  masses  are  composed  of  cells ;  the  black  areas  are  designed  to  represent 
conducting  fibers  running  vertical  to  the  plane  of  the  section ;  the  white  lines  repre- 
sent fibers  which  run  in  the  plane  of  the  section. 


cells,  which  have  become  separated  by  the  interposition 
of  some  fibers  destined  to  play  an  important  but  unknown 
part  in  the  varied  functions  of  the  medulla.  These  nu- 
clei all  act  upon  the  eye.  They  are  connected,  according 
to  some  authors,  by  distinct  fibers,  which  run  from  the 
abducens  nucleus  to  that  of  the  third  nerve  of  the  oppo- 
site side. 


GELATINOUS  SUBSTANCE  OF  MEDULLA.  263 

The  Upwaed  CoiS^TiT^uATioK  of  the  Posterior  Hori^s. 
— The  arcuate  fibers  of  the  medulla  separate  the  "  substantia 
gelatinosa "  from  the  rest  of  the  gray  substance,  near  to  the 
line  of  junction  of  the  spinal  cord.  This  portion  of  the  pos- 
terior horns  maintains  a  superficial  position  in  the  lateral  col- 
umn of  the  medulla,  as  high  as  the  point  of  escape  of  the  tri- 
geminus, or  fifth  nerve  from  the  pons.  In  the  opinion  of 
some  authors,  this  structure  may  be  regarded  as  prolonged 
through  the  aqueduct  of  Sylvius  as  far  as  the  level  of  its 
opening  into  the  cavity  of  the  third  ventricle. 

Spitzka  is  led  to  the  conclusion  that  the  gelatinous  sub- 
stance of  the  posterior  horn  is  not  composed  of  neuroglia 
tissue,  but  is  to  be  regarded  rather  as  imperfectly  organized 
ganglionic  tissue  which  is  connected  with  sensation.  He  is 
brought  to  this  view  by  the  following  facts :  1.  It  exists 
where  the  sensory  nerves  enter  the  posterior  horn ;  2.  It  is 
found  in  the  sensory  nuclei  of  the  medulla,  chiefly  in  the 
trigeminal  nuclei ;  3.  It  is  found  in  the  olivary  bodies  which 
are  connected  with  strands  from  the  posterior  columns  of  the 
cord,  above  the  nuclei  of  those  columns. 

The  posterior  spinal  cornua  are  continued  upward  into  the 
substance  of  the  medulla  upon  the  mesial  aspect  of  the 
ascending  root  of  the  fifth  cranial  nerve  (Fig.  57)  as  two  mass- 
es—the so-called  ^'spongy"  and  "gelatinous"  form  of  gray 
substance.  The  former  merges  with  the  gray  matter  of  the 
reticular  field ;  while  the  latter  lies  more  closely  related  to  the 
trigeminus  tract.  Spitzka  is  led  to  believe,  from  the  apparent 
connections  of  the  gelatinous  substance,  that  it  is  the  station 
for  sensory  impressions  derived  from  the  pharynx.  He  states 
his  grounds  for  this  belief  as  follows : 

'^Taking  into  account  that  the  three  nerves,  into  which 
the  eighth  pair  of  Willis  has  been  divided  by  Soemmering, 
supply  many  peripheries  conjointly,  I  think  it  unfortunate 
|that  investigation  should  seek  for  the  special  nucleus  of  this 
or  that  nerve,  designated  by  a  given  numeral.  Meynert  made 
a  step  in  the  right  direction  when  he  considered  the  nuclei  of 
the  ninth,  tenth,  and  eleventh  pairs  in  the  aggregate,  and 


264  THE  BRAIK 

classified  the  aggregate  nuclear  masses  on  tlie  topographical 
principle.  If  there  is  any  truth  in  the  notion  that,  with  a 
given  animal  species,  cells  have  special  connections,  present  a 
special  type  of  structure,  then  it  will  be  reasonable  to  seek 
for  the  nuclei  of  different  peripheries.  This  procedure  is  far 
more  rational  than  to  seek  for  the  nucleus  of  a  nerve  whose 
component  filaments  have  different  peripheral  terminations, 
and  are  included  in  the  same  sheath,  rather  by  anatomical 
accident,  as  it  were,  than  because  of  their  physiological  pro- 
pinquity. I  think  it  sound  to  speak  of  a  nuclear  column 
representing  the  visceral  periphery  of  the  vagus,  or  the  gusta- 
tory periphery  of  the  glosso  pharyngeal  and  intermediate 
nerve  of  Wrisberg,  or  the  tactile  periphery  of  the  ninth  and 
tenth,  the  motor  pharyngeal  periphery  of  the  same  nerves, 
and  the  motor  laryngeal  of  the  tenth  and  eleventh  pairs." 

The  Continuation  of  the  Central  Gray  Column  of 
THE  Spinal  Cord. — By  a  reference  to  Fig.  52  it  will  be  seen 
that  the  gray  substance  of  the  spinal  cord  on  either  side  of 
the  central  canal  is  represented  as  consisting  in  part  of  the 
*'gray"  or  "vesicular  column  of  ClarJce^^^  and  again  of  an 
intervening  portion  between  it  and  the  central  canal  called 
the  "  central  gray  column,'^'* ' 

The  COLUMN  OF  Clarke  is  well  defined  in  the  dorsal  region 
of  the  cord,  but  it  is  not  represented  in  the  cervical  or  lumbar 

*  The  gray  matter  of  the  cord  is  divided  by  Spitzka  into  three  parts,  viz. :  the  ante- 
rior horns,  or  motor  system ;  the  posterior  horns,  or  sensory  system  ;  and  the  intermedi- 
ate portion,  to  which  he  appHes  the  term  "  mixed  system,"  because  it  partakes,  to  his 
mind,  of  sensory,  motor,  and  trophic  functions.  He  attributes  a  trophic  function  to  the 
cells  of  Clarke's  column. 

The  followins:  formulae,  advanced  by  the  same  author  respecting;  the  functions  of 
cell  groups  in  the  central  tubular  gray  masses,  are  of  interest  in  this  connection: 

"  The  nearer  the  muscle  is  to  the  ventral  aspect  of  an  animal,  the  nearer  will  be  its 
nucleus  to  the  median  line  of  the  cord.  Per  contra,  the  nearer  the  muscle  is  to  the  dorsal 
line  of  an  animal,  the  nearer  to  the  so-called  lateral  cornu  will  its  nucleus  have  to  be 
sought  for.  Flexor  nuclei  are  therefore  in  internal,  extensor  nuclei  in  external  and  pos- 
terior, cell  groups." 

"  Hypertrophied  segments  of  the  body,  such  as  the  extremities,  are  accompanied  by 
lateral  extensions  of  the  cornua,  in  which  flexor  and  extensor  muscles  probably  occupy 
the  same  relative  position  as  the  one  stated. 

"  Whether  groups  of  muscles  be  flexor  or  extensor,  it  will  be  found  that  the  nearer 
they  are  to  the  animal  axis,  the  nearer  will  their  nuclei  be  to  the  central  canal.  This  is 
especially  true  of  the  flexor  nuclei." 


ACCESSORY  NUCLEI  OF  MEDULLA.  265 

regions.  In  the  lower  part  of  the  medulla,  however,  a  collec- 
tion of  cells  situated  at  the  posterior  and  external  part  of  the 
central  gray  column  may  be  discovered,  which  bear  a  close 
analogy  to  those  of  the  column  of  Clarke  encountered  in  the 
dorsal  region  of  the  cord.  It  contains  bipolar  cells  which  are 
markedly  pigmented,  and  constitutes  the  posterior  nucleus  of 
the  spinal  accessory  nerve,  which  is  given  off  at  this  level. 
At  higher  levels,  after  the  central  canal  has  opened  upon  the 
floor  of  the  fourth  ventricle,  this  column  seems  to  assist  in  the 
formation  successively  of  the  nuclei  of  the  eleventh,  tenth, 
and  ninth  cranial  nerves. 

The  CEi^TEAL  GRAY  COLUMN  of  the  cord  appears  to  be  con- 
tinued into  the  medulla  as  a  thin  layer  of  gray  substance 
which  covers  the  floor  of  the  fourth  ventricle,  and  is  prolonged 
as  a  lining  to  the  aqueduct  of  Sylvius. 

The  term  "nuclear  formation"  is  applied  to  the  cen- 
tral tubular  gray,  because  it  exhibits  a  tendency  in  higher 
animals  to  resolve  itself  into  nuclei  of  origin  for  special 
nerves. 

The  fourth  ventricle  maybe  regarded  as  an  expanded  por- 
tion  of  the  central  canal  of  the  cord,  in  order  that  sufficient 
room  shall  exist  for  the  nuclei  of  the  cranial  nerves  situated 
upon  its  floor. 

The  aqueduct  of  Sylvius^  with  its  surrounding  gray 
matter,  again  represents  from  this  standpoint  the  spinal 
canal  and  the  central  gray  column,  continued  onward  to 
the  third  ventricle. 

ACCESSOKY   N^UCLEI   OF    THE   MEDULLA   OBLONGATA. 

Within  the  apparent  continuation  of  the  central  gray  col- 
umn of  the  cord  upon  the  floor  of  the  fourth  ventricle  and  the 
aqueduct  of  Sylvius,  certain  collections  of  cells,  that  have  no 
representation  in  the  architecture  of  the  cord,  are  observed. 
These  have  been  named  the  '^  accessory  nucleV^  of  the  medul- 
la. They  require  a  separate  description.  These  include  the 
inferior  facial ;  the  accessory  nuclei  of  the  spinal  accessory 
and  hypoglossal  nerves  ;  and  four  acoustic  nuclei. 


266  THE  BRAIN-. 

Inferior  Facial  Nucleus.— "This  was  first  described  by 
Clarke.  It  consists  of  a  collection  of  several  small  masses  of 
cells,  which  lie  to  the  inner  side  of  the  hypoglossal  nucleus 
and  close  to  the  median  line.  Before  the  spinal  canal  opens 
into  the  ventricle,  they  lie  between  it  and  the  hypoglossal 
nucleus  of  either  side.  The  fibers  which  spring  from  them 
appear  to  enter  the  funiculus  teretes,  through  which  they 
ascend  to  the  fasciculus  teretes,  and  then  join  with  fibers  of 
the  facial  nerve.  This  nucleus  has  been  divided  by  some  au- 
thors into  two,  to  which  the  names  internal  and  external  have 
been  applied. 

Accessory  Nuclei  of  the  Spinal  Accessory  Nerve, — These 
consist  of  two  collections  of  cells  of  small  size,  which  are  situ- 
ated posteriorly  to  the  main  nucleus  of  the  spinal  accessory 
nerve.  According  to  Meynert,  these  nuclei  are  connected  by 
commissural  fibers  which  pass  posterior  to  the  central  canal. 

Accessory  Nucleus  of  the  Hypoglossal  Nerve. — Ross  de- 
scribes this  collection  of  cells  as  developed  princii)ally  upon 
one  side  only  of  the  medulla.  It  is  composed,  according  to 
this  author,  of  caudate  cells  of  extremely  small  size,  when 
compared  with  the  cells  of  the  hypoglossal  nucleus.  He  be- 
lieves that  this  accessory  nucleus  is  concerned  in  the  mechan- 
ism of  articulation,  and  that  it  is  reasonable  to  suppose  that  it 
is  in  some  way  connected  with  the  third  convolution  of  the 
left  frontal  lobe. 

Special  Nuclei  of  the  Medulla  and  Pons  Varolli. — 
Ross  includes  under  this  head  the  acoustic  nuclei,  because 
they  can  hardly  be  said  to  be  represented  by  any  part  of  the 
gray  substance  of  the  cord.  They  are  four  in  number,  two 
median  and  two  lateral. 

The  posterior  median  acoustic  nucleus  occupies  the  space 
between  the  ala  cinerea  and  the  inferior  peduncle  of  the  cere- 
bellum, as  high  as  the  anterior  border  of  the  ''stride  medulla- 
res."  It  gives  origin  to  the  posterior  root  of  the  auditory 
nerve.  Some  of  these  fibers  pass  out  superficially,  the  "  stride 
acousticse";  while  others  traverse  the  substance  of  the  me- 
dulla. 


GANGLIA    OF  PONS  AND  MEDULLA.  267 

The  anterior  median  acoustic  nucleus  lies  anteriorly  to 
the  strise  medullares,  and  gives  origin  to  the  anterior  root 
fibers  of  the  auditory  nerve.  It  occupies  the  external  angle 
of  the  ventricle. 

The  posterior  lateral  acoustic  nucleus  lies  imbedded  in 
the  peduncle  of  the  cerebellum,  and  is  interposed  between  the 
superficial  and  deep  fibers  of  the  auditory  nerve. 

The  anterior  lateral  acoustic  nucleus  is  situated  between 
the  middle  peduncle  and  the  flocculus.  It  gives  origin  to  the 
so-called  "portio  intermedia  of  Wrisberg."  The  view  that 
this  nucleus  is  associated  with  the  special  sense  of  taste  in 
the  anterior  two  thirds  of  the  tongue  (because  its  fibers  appear 
to  pass  in  the  chorda- tympani  branch  of  the  facial  nerve)  is 
now  held  by  some  anatomists. 

The  Superadded  Gray  Matter  of  the  Medulla  and 
Pons. — When  successive  cross- sections  of  the  medulla  and 
pons  are  compared  with  each  other,  nodal  masses  of  gray 
matter  are  discovered,  the  analogues  of  which  are  not  found 
within  the  brain  or  spinal  cord  ;  and  some  are  apparently  not 
directly  connected  with  the  fibers  of  origin  of  special  cranial 
nerves.  Most  of  these  have  been  incidentally  referred  to  in 
previous  pages,  but  a  few  remain  to  be  described.  These 
nodal  masses  include  (1)  the  so-called  ''triangular  nucleus^^ ; 
(2),  the  ''clanate  nucleus ^'^ ;  (3),  the  ''olivary  hody''^ ;  (4),  the 
"  par  olivary  body ''^  \  (5),  the  "  internal  par  olivary  hody^^^  or 
the  "nucleus  of  the  pyramid^''  \  (6),  the  "superior  olivary 
hody^^ ;  and  (7)  the  "middle  sensory  nucleus  of  the  trigemi- 
nus nerve,'''' 

The  "red  nucleus  of  the  tegmentum^'  or  the  "superior 
olive "  of  Luys  (which  has  been  already  described  in  connec- 
tion with  the  crus  cerebri),  as  well  as  the  "external  geniculate 
body ' '  (which  has  been  discussed  in  previous  pages),  are  also 
classed  by  Ross  among  these  superadded  collections  of  gray 
matter. 

The  Triangular  Nucleus.— TtA^  is  a  gray  nucleus  (Fig. 
53)  which  is  inclosed  within  the  substance  of  the  cuneate  bun- 

*  The  parolivary  bodies  are  often  designated  as  the  "  accessory  olivary  nuclei." 


268  THE  BRAIK 

die  or  Burdach's  column  (Fig.  52).  It  extends  cephalad  from 
the  lower  portion  of  the  medulla  as  high  as  the  posterior  end 
of  the  '*  posterolateral  acoustic  nucleus,"  and  increases  in 
size  as  it  ascends.  It  lies  along  the  inner  border  of  the  cunei- 
form column.  It  is  now  believed  that  all  the  fibers  of  the 
postero-latei-al  column  of  the  spinal  cord  (Burdach's  column) 
end  in  this  nucleus. 

The  Clavate  Nucleus. — This  mass  (Fig.  53)  is  situated 
within  the  continuation  of  the  fasciculus  gracilis  or  the  col- 
umn of  GoU  (Fig.  52)  into  the  medulla.  It  produces  an  en- 
largement of  this  bundle  of  fibers  called  the  ^'clava.^^  It 
extends  as  high  as  the  posterior  extremity  of  the  *' postero- 
lateral acoustic  nucleus."  Both  the  clavate  and  triangular 
nuclei  may  be  considered,  therefore,  as  pillars  of  gray  sub- 
stance which  run  in  the  long  axis  of  the  medulla.  The  fibers 
which  compose  the  postero-median  column  of  the  spinal  cord 
(Goll's  column)  probably  end  in  this  nucleus. 

The  nuclei  of  the  columns  of  GoU  and  Burdach  gradually 
disappear  as  the  central  canal  of  the  cord  expands  into  the 
fourth  ventricle. 

The  Olivary  Body.— This  structure  (Figs.  57  and  59)  is 
situated  in  the  lateral  column  of  the  medulla,  close  to  the  an- 
terior pyramid.  Its  gray  nucleus  is  not  seen  upon  its  sur- 
face, since  it  is  covered  by  longitudinal  and  transverse  fibers. 
The  olivary  body  takes  the  form  of  a  scalloped  or  wavy  layer 
which  is  open  at  one  point — the  hilus  of  the  olive.  This 
opening  looks  toward  the  median  line  of  the  body.  The 
fibers  which  pass  through  the  hilus  compose  the  so-called 
^* peduncle  of  the  olive:'  Some  of  the  relations  which  this 
body  bears  to  other  parts  are  depicted  in  a  previous  diagram 
(Fig.  55).  Certain  fibers  of  the  olivary  peduncle  pass  through 
the  lamina  of  the  olivary  nucleus,  and  constitute  the  so-called 
''arcuate  fibers"  (which  have  been  mentioned  on  a  previous 
page  as  helping  to  subdivide  the  gray  substance  of  the  ante- 
rior horns  at  the  junction  of  the  medulla  and  spinal  cord). 
The  cells  of  the  olivary  nucleus  {corpus  dentatum  of  the 
olive)  are  of  the  multipolar  variety  and  of  small  size. 


FIBER   TRACTS  OF  THE  MEDULLA.  269 

The  olivary  bodies  are  functionally  related  to  the  cerebel- 
lum. It  has  been  shown  that  atrophy  of  one  hemisphere  of 
the  cerebellum  is  always  associated  with  atrophy  of  the  oppo- 
site olivary  body.  The  libers  from  the  olivary  bodies  pass  to 
the  cerebellum  by  means  of  the  inferior  peduncles  (processes 
e  cerebello  ad  medullam — restiform  bodies). 

Spitzka  has  pointed  out  the  fact  that  the  gray  nucleus  of 
the  olive,  as  well  as  the  clavate  and  triangular  nuclei  of  the 
medulla,  are  highest  developed  in  man  and  the  anthropoid 
apes. 

TTie  Par  olivary  Bodies.— These  are  shown  in  Fig.  57. 
They  are  to  be  regarded  as  accessory  nuclei  to  the  olivary 
body.  One,  the  "internal  par  olivary  body,^^  lies  adjacent 
to  the  internal  half  of  the  posterior  border  of  that  body ;  the 
other,  or  "external  par  olivary  body,'^^  lies  in  front  of  the 
olivary  body,  and  to  its  inner  side.  Because  the  latter  lies 
immediately  behind  the  pyramid,  it  is  often  called  the  "nu- 
cleus of  the  pyramid.''^  The  fibers  of  origin  of  the  hypo- 
glossal nerve  pass  between  the  olivary  body  and  its  internal 
accessory  nucleus  after  traversing  the  peduncle  of  the  olive. 
Occasionally  these  fibers  penetrate  the  olivary  body. 

The  Superior  Olivary  Body, — This  long  gray  column  lies 
in  the  pons  Varolii,  in  front  of  the  facial  nucleus. 

THE   WHITE   SUBSTANCE   OF  THE   MEDULLA. 

Having  now  considered  the  collections  of  nerve  cells  or 
gray  matter  within  this  ganglion,  we  are  prepared  to  intelli- 
gently discuss  the  bundles  of  nerve  fibers  which  constitute  its 
white  substance. 

In  order  to  systematize  this  study,  it  is  necessary  to  im- 
press you  early  with  the  fact  that  two  general  classes  of  fibers 
>  may  be  recognized  here,  as  follows  :  (1)  Those  which  are  pro- 
longations of  the  fibers  found  within  the  white  substance  of 
the  spinal  cord^  and  (2)  superadded  fibers,  which  are  inde- 
pendent of  the  spinal  bundles. 

The  fibers  which  are  prolonged  from  the  spinal  cord  prob- 
ably traverse  the  entire  length  of  the  medulla  and  pons,  either 

20 


270  THE  BRAIN. 

totally  or  in  part,  and  then  pass  to  the  cerebrum  through  its 
peduncles  (the  crura).  These  bundles  are  found,  as  a  rule,  to 
occupy  portions  of  the  Internal  capsule  (Fig.  39)  after  leav- 
ing the  cms,  and  to  be  connected  with  the  cells  of  the  cere- 
bral cortex,  after  they  have  escaped  from  the  confines  of  the 
basal  ganglia,  and  have  radiated  throughout  various  areas  of 
the  central  mass  of  the  cerebral  hemispheres. 

In  previous  lectures  we  have  traced  some  of  the  bun- 
dles of  the  internal  capsule  from  above  downward,  taking 
their  cortical  attachments  as  the  starting-point  in  our  descrip- 
tion. It  is  now  deemed  advisable  to  reverse  the  order  of  de- 
scription, and  to  trace  them  from  the  spinal  cord  upward, 
noting  certain  peculiarities  in  the  course  which  each  pursues 
during  its  passage  successively  through  the  medulla,  pons, 
crus  cerebri,  internal  capsule,  and  corona  radiata,  as  w^ell  as 
the  area  of  the  cerebral  cortex,  to  which  each  is  probably  dis- 
tributed. Some  difficult  points  will  be  made  clear  to  the 
reader,  while  following  the  description  of  these  libers  in  a 
reversed  order,  by  consulting  certain  familiar  diagrams  which 
have  been  used  in  elucidating  previous  topics  (chiefly  Figs. 
8  and  63). 

The  diagram  of  the  main  subdivisions  of  the  spinal  cord, 
to  which  reference  was  made  on  page  250,  will  also  come  into 
play  again  here,  as  the  starting-point  from  which  the  different 
bundles  of  the  medulla  are  described. 

The  Pyramidal  Tracts.— The  motor  bundles,  which  serve 
to  connect  the  cells  of  the  cerebral  cortex  with  the  cells  of  the 
anterior  horns  of  the  spinal  gray  matter  (Fig.  52),  are  found 
in  two  distinct  columns  of  each  lateral  half  of  the  spinal 
cord. 

The  columns  of  Turck  (Fig.  46)  convey  those  bundles  of 
spinal  libers  which  are  associated  with  the  cerebral  hemi- 
sphere of  the  same  side.  These  do  not  decussate  in  the  me- 
dulla. 

The  ''  crossed  pyramidal  columns^'  (Fig.  46)  convey  fibers 
which  cross  within  the  medulla  to  the  opposite  side,  and 
which  are  therefore  connected  with  the  opposite  cerebral 


THE  PYRAMIDAL    TRACTS.  271 

hemisphere — the  right  column  with  the  left  hemisphere,  and 
the  left  with  the  right. 

Now,  within  the  medulla,  above  the  level  of  the  decussa- 
tion of  the  latter  fibers,  these  two  tracts  become  united,  as  it 
were,  in  the  region  of  the  pyramids  of  the  medulla.  This 
gives  them  the  name  of  the  ''pyramidal"  tracts.  They  pass 
upward  through  the  pons,  then  into  the  middle  third  of  the 
anterior  part  of  the  crus  cerebri  of  the  corresponding  side 
(the  "  crusta  cruris,"  Fig.  45),  and  eventually  reach  the 
cerebral  cortex  by  means  of  the  so-called  "internal  cap- 
sule" (Fig.  39).  How  these  tracts  become  united  within 
the  pyramids  of  the  medulla  should  now  engage  our  at- 
tention. 

At  the  upper  part  of  the  cervical  region  of  the  cord,  and 
in  the  lower  regions  of  the  medulla,  the  motor  fibers  of  the 
lateral  columns  of  the  cord  cross  the  median  line  in  order  to 
get  to  the  opposite  side.  In  so  doing,  they  come  forward 
close  to  the  anterior  median  fissure,  and  push  the  fibers  of 
Turck's  column  aside,  so  that  the  latter  lie  external  to  them 
in  the  so-called  "pyramids"  of  the  medulla.  As  we  trace 
them  cephalad,  the  two  tracts  do  not  apparently  intermingle. 
When  they  reach  the  level  of  the  pons,  they  receive  a  large 
accession  of  new  fibers.  This  fact  helps  to  explain  the 
marked  increase  in  the  apparent  size  of  these  tracts,  which 
may  be  observed  in  ctoss-sections  made  at  the  upper  border 
of  the  pons. 

Within  the  cerebral  peduncle  the  pyramidal  fibers  are 
packed  closely  into  one  compact  bundle,  which  occupies  the 
middle  third  of  the  "  crusta."  This  bundle  can  be  traced  up- 
ward into  the  "internal  capsule"  of  the  cerebrum,  lying  in 
its  thalamo-lenticular '  portion  (Fig.  39). 

Finally,  this  tract  emerges  from  between  the  basal  ganglia 
of  the  cerebrum,  without  any  apparent  association  with  the 
Us  which  compose  those  ganglia.     Its  fibers  then  radiate  to 


I" 

Km./. 


^  The  reader  is  referred  to  page  151  for  the  results  of  Flechsig's  latest  researches  in 
erence  to  this  tract.     The  pyramidal  tracts  lie  posteriorly  to  th£  "  knee  "  of  the  internal 


272  THE  BRAIN. 

the  motor  convolutions  of  the  cerebrum,  which  chiefly  bound 
the  fissure  of  Rolando. 

Within  the  substance  of  the  spinal  cord  this  tract  of  fibers 
gradually  diminishes  in  size  from  above  downward.  This  is 
because  small  fasciculi  are  given  off  constantly  (in  the  various 
segments  of  the  cord)  to  the  anterior  ganglion- cells  of  the 
spinal  gray  substance.  The  columns  of  Turck  usually  disap- 
pear at  about  the  middle  of  the  dorsal  region.  The  "  crossed 
pyramidal  tract "  of  the  lateral  column  extends  to  the  lower 
limits  of  the  cord  (origin  of  third  or  fourth  sacral  nerves) ; 
gradually  diminishing  in  size,  however,  as  it  descends. 

The  hypothesis  that  fibers  also  leave  the  pyramidal  tracts 
at  various  levels  in  the  pons  and  medulla,  and  pass  backward 
close  to  the  raphe  to  join  the  cranial  nerve  nuclei,  seems  to 
be  confirmed  by  late  investigations.  Some  of  these  fibers  un- 
questionably decussate  within  the  raphe. 

Flechsig  has  shown  that  the  relative  proportion  of  crossed 
and  direct  pyramidal  fibers  varies  greatly  in  individuals.  In 
a  few  of  the  spinal  cords  examined,  he  found  that  all  the 
fibers  decussated  ;  while,  as  the  opposite  extreme,  cases  were 
also  observed  where  no  decussation  occurred,  all  the  fibers 
passing  directly  downward  in  the  region  of  Tiirck's  column. 
These  observations  help  to  interpret  those  rare  cases  in  which 
hemiplegia  has  occurred  upon  the  same  side  as  the  cerebral 
lesion  which  caused  it. 

The  diagram  which  I  now  introduce  (Fig.  60)  will  illustrate 
the  areas  occupied  by  these  fibers  throughout  the  spinal  cord, 
and  the  filaments  which  the  two  columns  of  each  lateral  half 
of  the  cord  give  off,  during  their  descent,  to  the  cells  of  the 
anterior  horns  of  the  successive  spinal  segments. 

The  Accessory  Fibers  of  the  Pyramidal  Tract. — In 
cross-sections  of  the  medulla,  made  at  different  levels,  bundles 
of  fibers,  which  are  to  be  regarded  as  accessory  to  the  main 
pyramidal  tracts  already  described,  are  seen  to  occupy  the 
anterior  and  internal  margin  of  each  pyramid,  and  also  that 
part  of  the  lateral  column  which  adjoins  the  gray  substance, 
particularly  the  so-called  "  formatio  reticulaiis." 


ACCESSOEY  FIBERS  OF  MOTOR   TRACTS. 


273 


In  the  upper  portions  of  the  medulla  these  accessory  fibers 
become  very  abundant  and  tend  to  aggregate  toward  the 
pyramids. 

Within  the  substance  of  the  pons  some  of  these  accessory 
fibers  lie  to  the  inner  side  of  the  longitudinal  bundles  ;  in  the 
crura  they  appear  to  pass  along  the  inner  side  of  the  medul- 


Muscle. 


Fig.  60. —  TJie  paths  of  the  motor  fibers  of  the  cord.     (Modified  by  the  author  from 

BramwcU.) 

The  lines  show  the  course  of  the  fibers  given  off  from  the  pyramidal  tracts  associated 
with  the  left  cerebral  hemisphere  to  the  cells  of  each  spinal  segment  and  their 
continuation  into  the  motor  roots  of  the  spinal  nerves ;  the  arrows  indicate  the 
direction  of  the  currents ;  C.  P.  T.,  crossed  pyramidal  tract ;  S.  G.,  substantia 
gelatinosa. 


lated  fibers  of  the  ''  crusta"  of  either  side  ;  finally,  they  main- 
ly reach  the  cortex  of  the  frontal  lobes  of  the  cerebrum  after 
passing  through  the  internal  capsule,  in  front  of  its  knee. 

The  functions  of  these  accessory  fibers  are  not  positively 
determined.  They  unquestionably  end  within  the  substance 
of  the  medulla  and  pons,  and,  by  their  cerebral  connections, 
serve  to  unite  the  cells  of  the  cerebral  cortex  or  of  the  basal 
ganglia  with  the  cells  of  the  gray  masses  of  the  pons.  In 
this  way  they  probably  contribute  to  the  mutual  dependence 
of  the  subordinate  ganglia  and  those  of  the  cerebrum,  and 


274 


THE  BRAIK 


probably  help  to  bring  the  cerebrum  into  direct  association 
with  the  cerebellum  and  the  nuclei  of  the  cranial  nerves. 

The  longitudinal  fibers  of  the  pons  are  probably  related 
to  or  associated  with  fibers  that  leave  the  pyramidal  tracts 
to  join  the  cranial  nerve  nuclei.  Starr  found  them  wanting 
in  the  microcephalic  brain  examined  by  him,  as  were  also 
the  decussating  and  non-decussating  fibers  of  the  raphe  of 
the  pons.  This  fact  tends  to  confirm  the  view  that  the  fibers 
of  the  raphe  join  the  longitudinal  fibers  with  the  cranial 
nerve  nuclei. 

Upward  Continuation  of  the  Fibers  of  the  Anterior 
Boot  Zones  of  the  Spinal  Cord.— It  is  difficult  to  trace 
the  course  of  these  fibers  in  the  medulla,  because  they  are 
subdivided  into  small  bundles  by  the  arcuate  fibers  assisting 
to  form  the  so-called  '''formatio  reticularis y 


Direct  pyramidal 
columns. 


Crossed 
pyramidal 
oolomii. 


Fio.  61. — A  diagram  designed  by  the  axilhor  to  show  the  two  subdivisions,  or  tracts,  of 
Uie  anterior  root  zones  of  the  spinal  cord. 


Within  the  spinal  cord,  the  anterior  root  zones  are  sub- 
divided by  the  anterior  spinal  nerve  roots  (which  traverse 
them  to  reach  the  anterior  horns  of  the  gray  substance)  into  two 
distinct  portions,  an  internal  and  an  external  (Fig.  61).     The 


en 


FIBERS  OF  ANTERIOR  ROOT  ZONES.  275 

internal  portion  of  each  zone  lies  between  the  anterior  spinal 
nerve  roots  and  the  column  of  Turck ;  the  external  portion 
comprises  the  balance  of  the  anterior  root  zone.  Within  the 
medulla,  these  two  portions  take  a  different  course,  so  that 
each  must  be  described  separately. 

The  internal  portion  is  first  pushed  to  one  side  at  the 
lower  part  of  the  medulla  by  the  decussation  of  the  crossed 
pyramidal  tract.  Above  this  level,  where  the  olivary  body 
becomes  developed,  its  fibers  appear  to  be  thrust  backward 
behind  the  pyramids  and  close  to  the  median  raphe  of  the 
medulla.  At  this  level,  the  fibers  of  the  origin  of  the  hypo- 
glossal nerve  separate  it  from  the  external  portion. 

The  so-called  "posterior  longitudinal  bundle^''  of  each 
side  (which  has  been  described  in  previous  pages  that  treat 
of  the  crura  cerebri)  appears  to  be  a  direct  continuation  of 
the  internal  portion  of  the  anterior  root  zone  of  the  cord. 
Some  of  its  fibers  are  apparently  continued  into  the  thalamus 
and  thence  into  the  lateral  ventricle  ;  others  seem  to  join  the 
posterior  commissure  of  the  third  ventricle.  Like  other 
bundles  which  lie  close  to  the  aqueduct  of  Sylvius,  its  fibers 
become  medullated  very  early  in  the  development  of  the 
brain  of  the  human  embryo.  Those  tracts  of  nerve  fibers 
which  surround  it,  and  form  the  more  superficial  portions  of 
the  medulla,  become  medullated  at  a  later  period. 

The  posterior  longitudinal  bundle  and  the  round  or  soli- 
tary bundle,  both  of  which  bear  intimate  relationship  with 
the  nerve  nuclei  in  the  floor  of  the  fourth  ventricle,  probably 
serve  to  connect  these  nuclei  together  and  to  place  them  under 
the  control  of  the  ganglia  of  the  mesencephalon  (Spitzka). 

The  external  portion  of  the  anterior  root  zone  (Fig.  61) 
enters  into  the  formation  of  the  longitudinal  bundles  of  the 
ticular  formation  of  the  medulla. 

The  changes  which  occur  in  the  relative  position  of  the 
anterior  and  posterior  horns  of  the  gray  matter  within  the 
medulla  (chiefly  as  a  result  of  the  formation  of  the  fourth 
entricle  and  the  olivary  bodies,  in  addition  to  the  decussa- 
tion of  the  crossed  pyramidal  fibers)  cause  this  tract  of  fibers 


276  THE  BRAIN. 

to  assume  different  relations  to  adjacent  parts  than  are  repre- 
sented in  the  preceding  diagram. 

If  traced  upward,  this  tract  will  be  seen  to  lie  hehind  the 
olivary  body,  and  to  reach  the  surface  of  the  medulla,  in  its 
lateral  column.  Internally,  the  fibers  of  origin  of  the  anterior 
motor  nerves  bound  it;  posteriorly,  it  is  limited  by  gray 
matter ;  and,  externajly,  the  nerves  of  the  lateral  mixed  sys- 
tem are  detected. 


Fig.  62. — A  diagram  of  the  Hght  lateral  Jialf  of  a  transverse  section  of  tlie  pons  Va- 
rolii, on  a  level  with  tlie  origin  of  the  fifth  cranial  nerve.  (Modified  by  the  author 
from  Erb.) 

Rv,  root  of  trigeminus;  V,  middle  seusory  nucleus  of  the  trigeminus;  V,  motor  nu- 
cleus of  same;  dt,  descending  root  of  same;  P,  bundles  of  the  pyramidal  tract  cut 
across ;  jO,  accessory  fibers  of  same ;  Tr,  Tr',  transverse  fibers  of  the  pons,  consti- 
tuting the  '*  middle  peduncle  of  the  cerebellum  "  ;  R,  raphae ;  L,  posterior  longitudi- 
nal fasciculus ;  ar\  area  occupied  by  the  external  portion  of  anterior  zone  of  cord ; 
a?*,  area  occupied  by  the  internal  portion  of  same. 

Within  the  substance  of  the  pons^  the  interlacing  fibers  of 
that  region  lie  immediately  in  front  of  this  tract. 

When  this  tract  reaches  the  crus  cerebri^  it  is  only  sepa- 
rated by  the  substania  nigra  from  the  "cmsta  cruris." 

The  formatio  reticularis  lies,  wuthin  the  substance  of  the 
medulla,  between  the  pyramidal  tracts  and  the  gray  matter  of 


TEE  LEMNISCUS  TRACTS.  277 

the  fourth  ventricle,  in  a  ventro-dorsad  direction,  and  between 
the  ascending  root  of  the  trigeminus  nerve  and  the  inter- 
olivary  tract,  in  a  lateral  direction. 

In  the  region  of  the  pons,  the  formatio  reticularis  lies  be- 
tween the  fillet  (lemniscus)  and  the  gray  lining  of  the  fourth 
ventricle  in  a  vento-dorsad  direction,  and  between  the  raphe 
and  the  external  border  of  the  pons,  in  a  lateral  direction. 

The  view  that  the  reticular  formation  serves  as  a  channel 
for  the  transmission  of  the  tactile  sense  and  of  pain  sensa- 
tions to  the  cortex  of  the  parietal  lobes  is  supported  by  the 
late  researches  of  Starr.  Regarding  the  channel  for  the  trans- 
mission of  the  sensations  of  temperature,  no  positive  deduc- 
tions were  established  by  these  investigations  ;  although  it  is 
well  known  that  disturbances  of  pain  and  temperature  sen- 
sations usually  occur  together.  We  are,  therefore,  justified 
in  believing  that  they  both  travel  along  the  same  paths; 
until  more  is  definitely  established  regarding  temperature 
sensations. 

The  Fillet. — This  tract  of  fibers  {lemniscus)  has  been 
already  discussed  in  the  pages  devoted  to  the  consideration  of 
the  crura  cerebri.  It  springs  apparently  from  the  nuclei  of 
the  posterior  columns  of  the  opposed  side  of  the  cord,  and 
ascends  for  a  portion  of  its  extent  in  front  of  the  reticular 
formation  (Fig.  63).  It  terminates  apparently  in  the  thala- 
mus and  the  inferior  corpora  quadrigemina. 

Some  of  these  fibers  are  probably  continuous  with  the 
anterior  root  zones  of  the  corresponding  half  of  the  spinal 
cord,  while  others  are  connected  with  the  nuclei  of  the  pos- 
terior columns  of  the  cord.  Some  authors  describe  this  tract 
as  consisting  of  two  divisions  in  the  region  of  the  olivary 
body,  an  internal  and  an  external.  After  that  body  has  been 
passed,  both  of  these  divisions  appear  to  Join  and  to  pass 
upward  together  behind  the  transverse  fibers  of  the  ponSo 

The  latest  investigations  respecting  the  lemniscus  (Spitzka, 
Flechsig,  and  Starr)  seem  to  warrant  the  conclusion  that  two 
sets  of  fibers  are  comprised  within  it ;  one  of  which  degener- 
ates downward  and  the  other  upward.     About  one  half  of  it 


278     '  THE  BRAIN. 

appears  to  be  associated  in  some  way  with  the  motor  tracts, 
and  the  balance  with  the  sensory  tracts.  Flechsig,  Starr, 
and  Rohon  have  demonstrated  this  fact  in  microcephalic 
brains,  and  Spitzka  has  lately  sustained  the  same  view  by 
microscopic  investigations  of  a  case  which  bears  directly  upon 
this  field.  The  descending  degeneration  of  the  lemniscus 
seems  to  confine  itself  to  the  inner  half  or  two  thirds  of  that 
tract ;  hence  we  may  conclude  that  this  portion  of  the  fillet 
has  a  motor  function.'  The  outer  portion  of  the  fillet  ap- 
pears to  belong  to  the  sensory  tract ;  since  it  degenerates 
upward  and  apparently  extends  to  the  region  of  the  thalamus 
and  the  quadrigeminal  bodies.  This  conclusion  is  in  accord 
with  the  views  of  many  anatomists  as  well  as  with  late  patho- 
logical data. 

The  peculiar  course  of  the  fillet  tract  in  the  medulla  and 
pons  is  made  very  apparent  by  cross-sections  of  the  same  at 
different  levels.  In  its  lower  part,  this  tract,  after  particijjat- 
ing  in  the  sensory  decussation  of  the  medulla,  occupies  an  area 
that  lies  close  to  the  raphe  and  nearly  parallel  with  it  (the 
interolivary  tract).  As  it  ascends,  the  fibers  of  the  fillet  be- 
come displaced,  so  that  the  long  axis  of  the  oval  area  oc- 
cupied by  them  within  the  upper  part  of  the  pons  lies  nearly 
at  a  right  angle  to  the  raphe,  and  in  close  relation  to  the 
pyramidal  tracts.  Spitzka  compares  the  outline  of  this  tract  in 
cross- sections  made  through  the  mesencephalon  immediately 
caudate  of  the  lobes  to  the  capital  letter  L — the  extremities 
of  the  horizontal  portion  of  each  letter  meeting  the  raphe. 
Certain  fibers  of  the  medulla  that  arise  apparently  from  the 
clavate  and  triangular  nuclei  seem  to  pass  across  the  median 
line  (sensory  decussation  of  the  medulla)  into  the  opposite 
interolivary  tract,  and  from  that  into  the  tract  of  the  fillet. 

Within  the  medulla,  the  so-called  ''sensory  tracts"  that 
carry  impulses  from  the  spinal  cord  to  the  cerebrum  prob- 

'  Spitzka  19  inclined  to  doubt  the  infallibility  of  the  law  of  secondary  degeneration, 
viz.,  that  it  progresses  in  the  direction  of  the  currents  normally  conveyed  by  the  tracts. 
He  brings  forward  of  late  some  interesting  cases  of  secondary  degeneration  that  appear 
to  oppose  the  generally  accepted  view. 


THE  TRACT  OF  TEE  FILLET  270 

ably  comprise  the  forma tio  reticularis,  the  larger  part  of  the 
fillet,  and  the  interolivary  tract.  The  inferior  cerebellar 
peduncles  unquestionably  transmit  some  forms  of  sensory 
impulses  to  the  cerebellum  ;  but  it  is  still  an  open  question 
if  other  forms  of  sensations  are  not  sent  directly  to  the  cere- 
brum without  being  first  deflected  into  the  cerebellum. 

The  fillet  is  believed  by  some  observers  of  note  to  send  a 
slip  to  the  motor- oculi  nerve.  This  seems  to  confirm  the  view 
of  Stilling  that  the  fillet  is  connected  with  the  visual  appara- 
tus, since  the  optic  and  motor-oculi  nerves  are  intimately 
associated  with  each  other,  as  is  proved  by  the  reflex  move- 
ments of  the  pupil. 

The  reader  is  referred  to  previous  pages  for  further  infor- 
mation regarding  the  peculiarities  of  course  exhibited  by 
special  fasciculi  of  the  fillet,  and  some  late  views  which  have 
been  advanced  respecting  its  probable  functions. 

The  diagram  which  will  be  introduced  later  (Fig.  63)  will 
help  to  render  many  points  in  the  anatomy  of  the  spinal 
cord  and  medulla  more  intelligible  ;  while  its  text  will  aid 
the  reader  in  refreshing  his  memory  as  to  other  important 
details  of  construction  of  the  higher  ganglia  and  the  crus 
cerebri. 

The  fibers  which  cross  the  reticular  formation  in  the  dia- 
gram (F.  R.)  probably  enter  to  a  greater  or  less  extent  into  its 
composition. 

The  Direct  Cerebellar  TVac^^.— These  columns  of  the  spi- 
pal  cord  are  shown  in  Fig.  52,  and  the  fibers  which  compose 
them  are  depicted  in  a  diagrammatic  way  in  Figs.  63  and  64. 
Within  the  substance  of  the  cord  the  sensory  nerm  roots 
probably  communicate  with  these  columns  indirectly,  i.  e., 
through  the  vesicular  columns  of  Clarice.  In  order  to  do  so 
they  pass  chiefly  between  the  bundles  of  the  crossed  pyram- 
idal column  (Fig.  64,  a).  The  fibers  of  the  direct  cerebellar 
tracts  probably  afford  a  direct  communication  between  the 
gray  matter  of  the  superior  vermiform  process  of  the  cere- 
bellum and  the  cells  of  Clarke's  vesicular  column  in  the  cord. 
They  probably  terminate  in  the  cortex  or  central  gray  matter 


280 


THE  BRAIN, 


'  Spinal  Cord 


Fig.  63. — A  diagram  designed  by  the  author  to  illustrate  the  course  of  certain  special 
nerve  tracts  within  the  cerebrum^  cms  cerebri,  pons  Varoliij  medulla  oblongata,  and 
spinal  cord.     (Modified  by  the  author  from  Flechsig.) 

The  horizontal  dotted  lines  indicate  the  limits  of  the  crus,  pons  Varolii,  and  medulla.  The 
cerebellum  is  separated  intentionally  from  the  cerebrum  in  order  to  brinp^  the  crus 
cerebri  and  tubcrcula  quadrigemina  into  prominence.  C.  N.,  caudate  nucleus  of  the 
corpus  striatum ;  L.  N.,  lenticular  nucleus  of  the  same ;  0.  T.,  optic  thalamus  ;  G.  P., 
gray  matter  of  the  pons  Varolii;  F.R.,formatio  reticularis  ;  C.  D.,  corpus  dentatum 
of  the  cerebellum  ;  0.,  olivary  body  ;  N.  C,  clavate  nucleus ;  T.  N.,  triangular  nu- 
cleus ;  C.  Q.,  corpora  quadrigemina  ;  I.  C„  commencement  of  the  so-called  "  internal 
capsule''''  of  i$t  cerebrum  ;  m,  motor  centers  around  tlie  region  of  the  fissure  of  Ro- 
lando; c.  r.,  fibers  of  the  ^^ corona  radiata^^  ;  1,  the  fibers  of  the  so-called  ^^pyram- 
idal tract,^^  from  their  origin  in  the  motor  centers  of  the  cerebrum  to  their  termina- 
tion in  the  ganglion  cells  of  the  anterior  horns  of  the  spinal  pray  matter  (13  and  14), 
showing  also  the  decussation  of  the  fibers  at  the  lower  part  of  the  medulla  {d  and  c) ; 
2,  3,  and  4,  fibers  connecting  the  gray  substance  of  the  pons  with  the  cerebral  cortex, 
the  lenticular  nucleus,  and  the  caudate  nucleus ;  5,  fibers  of  the  superior  cerebellar 


DIRECT  CEREBELLAR   TRACTS. 


281 


peduncle^  passing  to  the  caudate  nucleus  and  the  optic  thalamus ;  6  and  7,  fibers  con. 
necting  the  gray  substance  of  the  pons  with  the  cerebellar  cortex  and  the  corpus 
dentatum ;  8,  fibers  joining  the  cerebellar  cortex  with  the  corpus  dentatum ;  9,  and 
10,  fibers  connecting  the  olivary  body,  with  the  corpus  dentatum  and  the  cerebellar 
cortex  of  the  opposite  side;  11,  the  so-called  ^'■direct  cerebellar  tract ^^  of  the  spinal 
cord ;  12,  the  fibers  of  the  '■^  filet  tract^''  connecting  the  olivary  body  with  the  thala- 
mus and  tubercula  quadrigemina — this  tract  is  probably  prolonged  cephalad  to  the 
cerebrum  and  dorsad  to  the  nuclei,  T.  N.  and  N.  C.  /  13,  the  ganglion  cells  of  the  an- 
terior horns  connected  with  the  "  crossed  pyramidal  tract "  (c) ;  14,  the  same,  con- 
nected with  the  '■'direct  pyramidal  trad''''  (d);  15,  fibers  of  the  column  of  Burdach^ 
terminating  superiorly  in  the  triangular  nucleus  (T.  N.);  16,  fibers  of  the  column  of 
Goll,  terminating  in  the  clavate  nucleus  (N.  C.) ;  1*7,  spinal  fibers  entering  the 
"reticular  formation"  directly;  18,  fibers  of  the  "inferior  peduncle  of  the  cere- 
bellum " ;  19,  paths  for  temperature  and  pain  sensations. 

of  the  worm  of  the  cerebellum.  They  reach  the  cerebellum 
by  means  of  the  inferior  peduncles  (processes  e  cerebello  ad 
medullam — restiform  bodies).  According  to  Wernicke,  the 
fibers  of  these  columns  decussate  after  entering  the  superior 
vermiform  process. 

The  direct  cerebellar  columns  are  considered  by  Meynert 
as  a  path  for  the  transmission  of  sensory  impulses.  This 
view  is  strengthened  by  the  fact  that  the  fibers  of  this  tract 
arise  from  the  cells  of  Clarke's  column,  whose  connection 
with  the  fibers  of  the  posterior  or  sensory  spinal  nerve  roots 


jlmf 


^M.F 


Fig 


.  64. — A  diagram  designed  hy  the  author  to  illustrate  the  relative  situation  a 
tional  association  of  the  direct  cerebellar  column  of  the  spinal  cora^and  the 


aiion  and  func- 

nd  the  vesicidar 

€olum7i  of  Clarke. 
C,  vescicular  column  of  Clarke ;  a,  fibers  connecting  it  with  the  direct  cerebellar  column, 
passing  between  the  bundles  of  the  crossed  pyramidal  tract.     The  other  letters  oji 
the  diagram  refer  to  the  fissure,  commissures,  horns,  and  the  older  subdivisions  of  the 
cord.     (See  previous  figures.) 


THE  BRAIN. 

has  been  positively  demonstrated.  They  also  exhibit  cen- 
tripetal degeneration  after  lesions  of  the  spinal  cord. 

The  fact  that  Clarke's  vesicular  column  is  found  only  in 
the  spinal  segments  functionally  associated  with  the  thorax 
and  abdomen  seems  to  warrant  the  belief  that  the  direct  cere- 
bellar tracts  are  in  some  way  associated  with  the  transmission 
of  visceral  sensations  from  the  thorax  and  abdomen  through 
the  cord  to  the  higher  centers  —  probably  the  cerebellum 
(Starr). 

Continuation  upwakd  of  Burdach's  and  Goll's  Col- 
umns.— These  two  columns,  which  compose  a  part  at  least  of 
the  sensory  or  "  sesthesodic  "  area  of  the  spinal  cord,  are  found 
to  terminate  apparently  in  the  cells  of  two  nuclei  which  are 
situated  in  the  lower  half  of  the  medulla.  That  of  Goll's  col- 
umn is  called  the  "clavate  nucleus, "^^  or  nucleus  gracilis; 
that  of  Burdach's  column  the  'Hriangular  nucleus, "^^  or  nu- 
cleus cuneatus  (Fig.  53).  The  fibers  are  probably  interrupted 
by  the  cells  of  the  nuclei  referred  to.  These  fasciculi  inclose 
the  two  nuclei  which  have  been  mentioned,  and  are  increased 
in  size  by  their  interpolation. 

A  tract  known  as  the  ^'ascending  root  of  the  fifth  cranial 
nerve,^^  and  also  one  called  the  ''fasciculus  rotundus,^^  are 
formed  by  fibers  apparently  derived  from  the  posterior  root 
zones  of  the  spinal  cord,  which  have  no  apparent  connection 
with  the  two  nuclei  described  above  (Fig.  45). 

The  fasciculus  rotundus^  has  been  named  by  Meynert 

*  The  80-called  "  round  "  or  "  solitary  "  bundle  of  the  medulla  has  attracted  the  atten- 
tion of  Clarke,  Stilling,  Krause,  Meynert,  Spitzka,  and  others. 

Krause  has  named  it  the  "  respirator  bundle,"  from  a  connection  which  he  believes 
can  be  demonstrated  between  it  and  the  origin  of  the  phrenic  nerve  in  the  spinal  cord. 
Spitzka  rejects  this  view,  and  applies  the  name  "  trineural  bundle  "  to  this  tract,  because 
he  believes  that  its  efferent  fibers  can  be  traced  to  three  cranial  nerves,  viz.,  the  ninth, 
tenth,  and  eleventh.  He  considers  it  as  an  "  aberrant  ramus  of  the  ninth  pair,"  and  sus- 
tains the  view  advanced  by  Duval  and  Bigelow  that  its  cephalic  end  passes  into  the  inter- 
mediary nerve  of  Wrisberg,  whose  function  is  still  in  doubt,  although  it  is  believed  by 
some  to  be  coiljlected  with  the  gustatory  sense.  The  same  author  states  that,  in  his 
opinion,  the  fibers  of  this  bundle  are  derived  from  the  opposite  posterior  column  of  the 
cord  (that  of  GoU),  or  from  the  lemniscus  tract  and  the  stratum  intermedium.  It  seems 
to  be  positively  demonstrated  that  some  fibers  of  the  sensory  tracts  of  the  cord  exhibit  a 
medullary  decussation,  analogous  to  that  of  the  pyramidal  fibers,  as  was  originally  advo- 
cated by  Meynert. 


THE  SENSORY  TRACTS,  283 

the  ''ascending  root  of  the  lateral  mixed  system,"  and  by 
Krause  the  "respiratory  fascicle."  It  consists  of  fibers  which 
are  disposed  longitudinally,  and  which  become  detached  from 
the  posterior  root  zone  in  the  upper  part  of  the  cervical  re- 
gion of  the  spinal  cord. 

The  increased  size  of  the  fasciculus  gracilis  and  the  fas- 
ciculus cuneatus  within  the  medulla  causes  the  posterior 
horn  of  the  spinal  gray  matter  to  be  displaced  outward  and 
forward,  so  that  the  continuation  of  the  gelatinous  sub- 
stance forms  a  collection  of  gray  matter  upon  the  lateral 
aspect  of  the  medulla,  designated  as  the  "tubercle  of 
Rolando  y 

The  Sensory  Tracts.— The  course  of  each  of  the  sensory 
tracts  in  the  mesencephalon  is  variously  described  by  differ- 
ent observers  of  note.  So  wide  are  the  variations  in  descrip- 
tion that  it  is  impossible  to  bring  all  the  published  views  into 
harmony.  Starr  has  lately  undertaken  the  task  of  collecting 
all  the  published  autopsies  that  bear  upon  the  solution  of 
this  difficult  problem.  He  arrives  at  the  conclusion  that  the 
views  of  Flechsig,  based  upon  anatomical  and  embryological 
researches,  are  sustained  by  pathological  investigation  and 
also  by  an  experiment  lately  made  by  Yon  Monakow  after  the 
method  of  Gudden.  He  confirms  this  deduction  also  by  a 
microscopical  investigation  of  a  microcephalic  brain,  in  which 
all  the  motor  tracts  of  the  mesencephalon  were  wanting — thus 
affording  an  unusual  opportunity  for  the  study  of  the  sen- 
sory tracts,  apart  from  the  motor.  Thus  he  believes  that  the 
conclusions  advanced  by  him  are  supported  by  four  methods 
of  research,  each  totally  different  from  the  other. 

This  observer  is  led  to  the  following  conclusions  : 

1.  That  the  outer  part  of  the  formatio  reticularis  and  the 
interolivary  tract  (probably  a  part  of  the  fillet)  convey  sensory 
impulses  through  the  medulla.  The  root  of  the  hypoglossal 
nerve  divides  the  reticular  formation  of  the  medulla  into  an 
inner  and  outer  portion. 

2.  That  the  formatio  reticularis  and  the  fillet  perform  the 
same  function  in  the  pons.     The  fillet  (lemniscus  tract)  is  be- 


284  THE  BRAIN. 

lieved  by  this  observer  to  be  associated  with  the  so-called 
' '  muscular  sense. " 

3.  That  the  sensations  of  pain,  touch,  and  temperature 
travel  along  the  formatio  reticularis  to  the  cerebrum  without 
decussation  in  the  medulla  and  pons,  because  the  fibers  con- 
nected with  the  transmission  of  such  impulses  have  decus- 
sated completely  within  the  substance  of  the  cord. 

4.  That  the  fibers  which  convey  sensations  included  under 
the  term  "muscular  sense"  do  not  decussate  in  the  cord. 
They  cross  at  the  lower  part  of  the  medulla,  in  the  "pinni- 
form  decussation"  of  Spitzka,  and  pass  upward  through  the 
interolivary  tract  and  the  fillet  of  the  opposite  side.  They 
are  thus  conducted  to  the  internal  capsule  of  the  cerebrum. 

6.  That  all  sensory  impulses  which  are  deflected  to  the 
cerebellum  are  destined  to  awake  reflex  action  only. 

The  fibers  of  the  cuneate  bundle,  after  they  have  become 
associated  with  the  gray  substance  of  the  triangular  nucleus, 
resolve  themselves  apparently  into  the  so-called  ^'arcuate 
fibers.''^  These  pass  forward  and  upward  to  the  olivary  body 
of  the  same  side,  and  therefore  connect  two  nuclei  of  the 
medulla  with  each  other.' 

*  If  the  main  columns  of  the  cord  be  traced  upward  into  the  substance  of  the  medulla, 
they  will  be  found  to  be  related  as  follows :  The  anterior  columns  (those  of  Tiirck)  and 
the  crossed  pyramidal  columns  form  the  anterior  pyramids  of  the  medulla ;  the  lateral 
columns  are  continuous  with  the  restiform  body;  the  columns  of  Burdach  with  the 
cuneate  bundle ;  and  the  columns  of  GoU  with  the  processus  gracilis.  Spitzka  believes 
that  the  fibers  of  Burdach's  columns  are  continued  into  the  restiform  body  (some  after 
decussation  and  some  directly)  as  are  those  of  the  cerebellar  tract ;  and  that  they  pass 
to  the  cerebellar  cortex.  The  same  author  states  that  the  fibers  of  the  postero-extemal 
column  are  traceable  to  the  nucleus  fastigii  of  the  cerebellum. 

Starr  is  led  to  believe,  from  an  analysis  of  collected  cases  of  focal  lesions  within  the 
medulla  and  pons,  that  the  fibers  from  the  posterior  columns  of  the  spinal  cord  pass 
chiefly  into  the  interolivary  tract  and  the  lemniscus.  This  author  advances  some  strong 
arguments  in  favor  of  the  view  that  the  sensory  tracts  pass  directly  through  the  medulla, 
pons,  and  crus  without  decussation  or  deflection  into  the  cerebellum,  and  that  they  subse- 
quently reach  the  cerebral  cortex  by  means  of  the  internal  capsule. 

Within  the  lower  part  of  the  medulla,  the  sensory  tracts  (according  to  Starr)  consist 
of  three  columns,  called  the  funiculus  gracilis,  the  funiculus  cuneatus,  and  the  formatio 
reticularis,  and  one  tract  which  is  the  direct  continuation  of  the  direct  cerebellar  column 
of  the  cord.  The  course  of  sensory  impulses  through  the  gray  columns  is  a  subject  upon 
which  difl'erent  opinions  are  held  by  various  observers.  Dr.  Starr  has  given  an  excellent 
summary  of  the  views  held  upon  this  subject  in  his  late  article  on  "  The  Sensory  Tract 
in  the  Central  Nervous  System"  ("Journal  of  Mental  and  Nervous  Diseases,"  July,  1884). 


SENSORY  TRACTS  OF  MEDULLA.  285 

The  fibers  of  the  fasciculus  gracilis  have  probably  a  simi- 
lar continuation  above  the  interpolation  of  its  nucleus ;  al- 
though some  authors  assert  that  a  decussation  of  its  fibers 
can  be  demonstrated  to  exist. 

Some  anatomists,  among  whom  Meynert  may  be  promi- 
nently mentioned,  believe  that  a  decussation  of  the  sensory 
conduction  paths  takes  place  within  the  lower  part  of  the 
medulla.  The  sensory  fibers,  according  to  Meynert,  issue 
from  the  triangular  and  clavate  nuclei  and  pursue  an  arcuate 
course  around  the  central  gray  column  to  reach  the  inter- 
olivary  tract,  near  to  the  mesial  and  posterior  portion  of  the 
anterior  pyramid  of  the  opposite  side.  The  view  of  Flechsig, 
however,  that  the  arcuate  fibers  enter  the  substance  of  the 
olivary  body  of  the  same  side,  is  the  one  most  generally  ac- 
cepted. The  paths  of  sensory  conduction  will  be  discussed 
more  fully  in  connection  with  the  description  of  the  spinal 
cord. 

The  arcuate  fibers  of  the  medulla  are  divided  into  a  super- 
ficial and  a  deep  set.  The  former  pass  over  the  olivary 
bodies,  and  lie  near  the  anterior  aspect  of  the  medulla.  The 
deep  set  have  been  traced  by  some  authors  to  the  cuneate 
bundle  and  fasciculus  gracilis  of  the  opposite  side  of  the 
medulla,  to  the  raphe  of  the  medulla,  and  to  the  cells  found 
in  the  nucleus  of  the  restiform  body. 

The  arcuate  fibers  of  the  medulla  probably  belong  to  the 
sensory  tracts.  They  were  found  by  Starr  to  be  normally 
developed  in  a  microcephalic  brain  which  lacked  the  motor 
tracts. 

The  late  paper  by  Starr  upon  the  sensory  tract  of  the 
central  nervous  system '  contains  a  collection  of  cases  which 
seem  to  conflict  with  the  deductions  of  Wernicke,  Spitzka, 
and  others,  viz.,  that  the  sensory  tract  is  to  a  great  extent 
deflected  from  the  medulla  below  the  pons  into  the  cerebel- 

One  difficulty  that  arises  is  that  Flechsig's  method  of  research  is  unsatisfactory  in  the 
medulla.  Gudden's  method  has  been  successfully  tried  in  but  one  instance,  and  inves- 
tigations of  microcephalic  brains  have  not  yet  been  given  much  attention  by  neurologists 
or  anatomists. 

*  "Journal  of  Nervous  and  Mental  Diseases,"  July,  1884. 
21 


286  '  THE  BRAIK 

lum,  and  that  sensory  impulses  do  not  traverse  the  pons. 
Lesions  of  the  pons  are  shown  by  this  author  to  have  resulted 
in  marked  disturbances  of  sensation  of  the  opposite  half  of 
the  body.  He  draws  the  deduction  that  the  sensory  tract 
for  each  side  of  the  body  traverses  the  opposite  half  of  the 
medulla  and  pons,  and  that  no  decussation  of  these  tracts 
can  be  verified  (by  clinical  data)  between  the  sensory  decus- 
sation at  the  lower  limit  of  the  medulla  and  the  upper  bor- 
der of  the  pons.  Respecting  the  views  of  Wernicke  and 
Spitzka,  this  author  speaks  as  follows  : 

"It  is  very  possible  that  some  sensory  impulses  may  pass 
to  the  cerebellum  by  the  tracts  described  by  Wernicke  and 
Spitzka,  and,  setting  up  there  a  reflex  action,  be  the  means  of 
exciting  that  organ  to  do  its  reflex  work.  But,  if  so,  these  are 
not  the  sensory  impulses  which  pass  to  the  higher  cortical 
cerebral  centers,  or  which  are  destined  to  awake  in  conscious- 
ness a  perception  of  the  sensation.  The  sensations  which  are 
perceived  consciously  are  transmitted  directly  from  the  surface 
of  the  body  through  the  spinal  cord,  medulla,  and  pons,  into 
the  internal  capsule  and  thence  to  the  cortical  centers,  and  in 
their  course  undergo  but  one  decussation.  If  that  decussa- 
tion is  complete  in  the  cord,  the  tract  remains  on  the  same 
side  from  the  cord  to  the  capsule.  If  that  decussation  does 
not  occur  in  the  cord,  it  takes  place  in  the  sensory  decussa- 
tion at  the  lower  part  of  the  medulla." 

The  Superadded  White  Substance  of  the  Medulla 
AND  Pons. — Under  this  head  the  fibers  of  the  cerebellar  pe- 
duncles may  be  considered.  In  previous  pages  the  superior 
and  middle  peduncles  of  that  ganglion  have  received  due 
consideration,  and  the  reader  is  referred  to  them  for  further 
information,  as  only  the  main  points  will  be  here  touched 
upon.  The  inferior  peduncles  have,  however,  been  incom- 
pletely described  in  previous  pages,  and  therefore  merit  a 
more  detailed  description. 

The  Inferior  Peduncles  of  the  Cerebellum  (processus  e 
cerebello  ad  medullam).— If  a  cross-section  of  the  medulla  at 
the  level  of  the  apparent  origin  of  the  auditory  nerve  (Fig. 


FIBERS  OF  RESTIFORM  BODIES.  287 

57)  be  studied,  two  collections  of  fibers  will  be  apparent  in 
the  latero-posterior  area  of  the  section  npon  either  side  {ep 
and  ip\  which  together  assist  to  form  the  inferior  cerebellar 
peduncle. 

The  external  dimsion  has  been  named  by  Stilling  the 
'' r est i form  'body.''''  Its  fibers,  if  traced  from  above  down- 
ward, start  apparently  from  the  cortex  of  the  cerebellum, 
and  also  from  a  layer  of  fibers  surrounding  the  *' corpus 
dentatum."  As  they  descend  toward  the  medulla,  these 
fibers  are  split  up  into  two  bundled  by  those  of  the  "direct 
cerebellar  tract,"  which  join  the  cerebellar  cortex  in  the 
region  of  the  worm.  At  birth,  the  fibers  of  the  latter  tract 
are  distinctly  meduUated,  while  the  peduncular  fibers  are 
not,  thus  rendering  the  outline  of  the  two  sets  very  ap- 
parent. 

The  fasciculi  of  the  restiform  body  become  ''''arcuate 
fibers  "  within  the  medulla.  These  course  first  through  the 
so-called  ''''zonular  layer^''  in  front  of  the  olivary  body ;  then 
they  reach  the  median  raphe  of  the  medulla  by  forming  two 
bundles,  one  of  which  passes  in  front  of  and  the  other  behind 
the  anterior  pyramid  of  the  same  side ;  finally,  they  appear  to 
cross  the  raphe,  to  terminate  in  the  olivary  body  of  the  oppo- 
site side  of  the  medulla.  The  fibers  which  cross  in  front  of 
the  pyramids  are  commonly  known  as  the  '^arciform  fibers" 
of  the  medulla. 

The  raphe  of  the  medulla  and  pons  probably  contributes 
fibers  to  the  round  or  solitary  bundle  (trineural  bundle  of 
Spitzka),  the  posterior  longitudinal  bundle,  and  the  lemnis- 
cus or  fillet  tract.  Fibers  are  also  traced  from  it  to  the  retic- 
ular field.  These  are  believed  by  some  authors  to  bear  a  rela- 
tionship to  facial  expression  and  to  articulate  speech.  The 
superficial  and  deep  arcuate  fibers  are  also  connected  with 
the  raphe.  The  raphe  is  crossed  by  the  decussating  fibers 
between  the  olives,  and  also  by  those  constituting  the  "  pinni- 
form  "  decussation. 

The  existence  of  an  independent  decussation  of  sensory 
fibers  within  the  medulla,  as  well  as  those  associated  with 


288  TEE  BRAIN. 

motion,  has  been  apparently  demonstrated  by  the  micro- 
cephalic brain  examined  by  Starr,  in  which  the  pyramidal 
tracts  were  wanting.  It  was  found  to  lie  upon  the  same  level 
as  the  decussation  of  the  motor  fibers. 

The  interolivary  tract  contains  strands,  according  to  the 
investigations  of  the  same  author,  that  develop  both  from 
below  upward  and  from  above  downward.  The  sensory  por- 
tion of  this  tract  is  in  relation  with  the  triangular  and  clavate 
nuclei. 

The  internal  dimsidn  is  described  by  Stilling  as  arising 
from  the  nuclei  of  the  ventricular  roof,  and,  after  reaching 
the  medulla,  as  resolving  itself  into  arcuate  bundles  which 
become  intermingled  with  the  ascending  fibers  of  the  ante- 
rior root  zone  of  the  spinal  cord,  behind  the  olivary  body  of 
the  corresponding  side. 

Some  anatomists  describe  these  arcuate  fibers  as  capable 
of  being  traced  across  the  median  raphe  of  the  medulla,  and 
into  the  olivary  body  of  the  opposite  side. 

Prom  what  has  been  said,  it  will  be  apparent  that  the 
olivary  body  of  each  half  of  the  medulla'  is  a  medium  of 
communication  between  fibers  which  spring  from  the  tri- 
angular and  clavate  nuclei  and  those  of  the  restiform  bod- 
ies and  the  remaining  bundles  of  the  inferior  cerebellar 
peduncles.  The  physiological  functions  of  the  masses  of 
gray  matter  which  are  interpolated  (the  triangular  and 
clavate  nuclei  and  the  olivary  bodies)  are  as  yet  somewhat 
conjectural. 

Focal  lesions  of  the  medulla,  pons,  or  cms,  are  not  in- 
frequently of  limited  extent ;  but  few  cases,  however,  are 
well  adapted  for  anatomical  deductions.  Disease  of  the 
basilar  artery,  resulting  in  thrombosis  or  apoplexy,  is  most 
frequently  the  direct  cause  of  lesions  of  the  pons ;  and  the 
motor  tracts  (which  lie  ventrad  of  the  sensory)  are  most 
commonly  affected  by  disease.  Lesions  of  the  dorsal  half  of 
the  pons  are  almost  immediately  fatal,  as  centers  of  the  pneu- 


*  The  olivary  body  (dentate  body  of  the  medulla)  has  two  accessory  nuclei  associated 
with  it,  the  so-called  "  external  olivary  body  "  and  "  internal  olivary  body  "  of  Meynert. 


i 


FIBERS  OF  RE8TIF0RM  BODIES.  289 

mogastric  nerves  rarely  escape  injury.  ~^o  disturbances  of 
sensation  are  ever  produced  by  lesions  of  the  pons  unless 
they  are  situated  posterior  to  its  deep  transverse  fibers  (Starr). 
This  fact  points  positively  to  the  inference  that  the  pyramidal 
tracts  and  the  gray  matter  of  the  pons  are  not  concerned  in 
any  way  in  the  transmission  of  sensory  impulses.  That  the 
gray  matter  of  the  ventricular  floor  of  the  medulla  and  pons 
has  nothing  to  do  with  sensation  seems  to  be  proved  by  the 
cases  collected  by  Starr,  where  disease  of  the  cranial  nerve 
nuclei  failed  to  produce  sensory  symptoms  in  the  body. 
Lesions  of  the  gray  matter  of  the  fourth  ventricle  must 
first  create  pressure- effects  upon  adjacent  parts  in  order 
to  cause  anaesthesia  or  other  sensory  symptoms  below  the 
head.  The  opinion  of  Meynert  that  the  descending  root 
of  the  fifth  cranial  nerve  decussates  within  the  substance 
of  the  pons  appears  to  be  sustained  by  clinical  statistics. 
Lesions  affecting  it  produce  anaesthesia  of  the  opposed  side 
of  the  face. 

According  to  the  observations  of  Spitzka,  the  restiform 
body  of  either  side  may  be  regarded  as  composed  of  the  fol- 
lowing parts :  1.  The  fibers  of  the  direct  cerebellar  tract  of 
the  same  side.  2.  The  decussating  fibers  of  the  opposite 
postero-external  column  of  the  cord,  which  have  previously 
passed  through  the  olivary  body.  3.  Some  fibers  of  the  pos- 
tero-external column  of  the  same  side.  This  author  discards 
the  fibers  of  GoU's  columns  from  participation  in  the  cerebel- 
lar circuit.  He  believes  that  these  fibers  cross  to  the  opposite 
side  in  the  so-called  sensory  decussation  of  the  medulla,  and 
that  they  then  pass  directly  upward  through  the  posterior 
longitudinal  fibers  of  the  pons  (stratum  intermedium)  to  the 
posterior  part  of  the  internal  capsule  of  the  cerebral  hemi- 
sphere. 

This  view  is  opposed  to  that  of  Starr,  which  has  been  pre- 
viously referred  to,  since  it  presupposes  a  double  decussation 
of  the  sensory  tracts,  derived  from  Burdach's  column  between 
the  spinal  cord  and  the  internal  capsule— one  in  the  medulla, 
and  again  by  means  of  the  middle  or  superior  cerebellar  pe- 


290  THE  BRAIN. 

duncle.  The  deductions  of  Starr  are  based  largely  upon 
clinical  facts,  supplemented  by  original  research  made  upon 
a  microcephalic  brain,  in  which  all  the  motor  tracts  were 
wanting. 

The  Middle  Peduncle  of  the  Cerebellum  (processus  e  cere- 
bello  ad  pontum). — The  fibers  of  this  set  arise  from  the  cere- 
bellar cortex  and  pass  forward,  both  in  front  of  and  through 
the  substance  of  the  pons,  eventually  decussating  with  those 
of  the  opposite  cerebellar  hemisphere  in  the  median  line.  By 
so  doing,  they  assist  in  separating  the  fibers  of  the  pyramidal 
tract  into  distinct  bundles,  as  is  shown  in  previous  cuts  (Fig. 
58).  After  crossing  the  median  line,  they  join  with  the  cells 
of  the  gray  matter  of  the  pons.  Here  they  probably  become 
associated  with  fibers  which  descend  from  the  inner  third  of 
the  crusta  cruris. 

These  transverse  fibers  are  wanting  in  animals  which  do 
not  possess  cerebellar  hemispheres.  In  previous  pages,  these 
fibers  have  been  discussed  in  detail. 

The  Superior  Peduncle  of  the  Cerebellum''  (processus  e 
cerebello  ad  cerebrum). — It  is  probable  that  most  of  the  fibers 
of  this  process  are  derived  from  the  corpus  dentatum.  They 
decussate  within  the  substance  of  the  tegmentum  cruris  and 
become  more  or  less  associated  with  the  cells  of  the  red 
nucleus  of  the  tegmentum  of  the  opposite  side.  The  terminal 
distribution  of  these  fibers  is  still  a  matter  of  dispute  among 
authorities  of  note.  Some  believe  that  they  pass  to  the  optic 
thalamus  ;  others  state  that  they  pass  to  the  cortex  of  the 
cerebrum  ;  while  a  few  think  that  they  can  be  traced  to  the 
caudate  and  lenticular  nuclei  of  the  corpus  striatum.  The 
functions  which  have  been  attributed  to  this  process  of  the 
cerebellum  have  been  aUuded  to  in  previous  pages  (which 
treat  of  the  corpus  striatum,  the  crus  cerebri,  and  the  general 
architecture  of  the  nervous  system  of  man)  to  which  the 
reader  is  referred  for  further  information. 

'  The  three  peduncles  of  the  cerebellum  have  been  named  by  Wilder  and  Spitzka, 
from  above  downward,  the  "  praepedunculus "  or  "  tegmenta  brachium,"  the  "  ponti- 
braehium,"  and  the  *'  post-pedunculus  "  or  "  myelo-brachium." 


FUI^CTIONS  OF  PONS   VAROLII.  291 


THE  FUNCTIONS   OF  THE  PONS  VAROLII  AND   THE  DIAGNOSTIC 
SYMPTOMS  OF  LESIONS  AFFECTING  IT. 

The  fibers  that  form  the  larger  portion  of  this  mass  are 
abundantly  supplied  with  gray  matter,  which  seems  to  be 
mixed  throughout  its  interior.  We  may  infer  from  this 
fact  that  they  have  some  individual  functions,  in  addition 
to  being  simply  connecting  commissures  ;  but  what  these 
functions  are  it  is  difficult,  at  present,  to  positively  state 
in  every  instance. 

Both  the  pons  and  crura  cerebri  are  unquestionably  con- 
nected in  some  way  with  the  power  of  coordination  of  mus- 
cular movement,  since  injuries  to  either  of  them  may  result 
in  marked  disorder  of  this  function,  and  often  in  unnatural 
and  forced  movements.  This  function  is  probably  associated 
with  the  fillet  tract. 

The  fact  that  some  of  the  nerve  fibers  (probably  those  of 
the  fifth  and  seventh  pairs)  decussate  in  these  regions  seems 
proven  by  clinical  evidence,  since  lesions  of  the  pons  Varolii 
often  produce  paralysis  of  the  facial  nerve  upon  the  same 
side  as  the  lesion,  while  the  opposite  side  of  the  body  is  af- 
fected below  the  face.'  Crossed  hemiansesthesia  may  also 
occur  from  a  lesion  in  the  sensory  tracts  of  the  pons  (formatio 
reticularis). 

The  facial  nerve  makes  its  exit  from  the  side  of  the 
medulla  oblongata  ;  some  of  its  roots  of  origin  can  be  traced 
as  far  as  the  floor  of  the  fourth  ventricle,  some  come  from  the 
lower  part  of  the  medulla  oblongata,  while  others  descend 
from  the  upper  border  of  the  pons  Varolii,  and  probably 
decussate.     Now,  a  lesion  existing  in  the  lower  half  of  the 

'  A  class  of  paralysis,  where  certain  cranial  nerves  are  paralyzed  on  the  same  side 
as  the  existing  lesion,  while  the  body  is  rendered  hemiplegic  on  the  opposite  side,  is 
call  "  crossed  paralysis  "  (the  "  paralysie  altcrne  "  of  the  French).  It  presents  several 
types  depending  upon  the  cranial  nerve  affected  ;  hence  the  so-called  third  nerve  (motor- 
oculi)  and  body  type,  the  fifth  nerve  (trigeminus)  and  body  type,  the  seventh  nerve 
(facial)  and  body  type.  Professor  Romberg,  of  Berlin,  and  Gubler,  of  Paris,  have  done 
much  to  elucidate  the  clear  appreciation  of  this  complex  form  of  paralysis  and  the 
mechanism  of  its  production.     They  have  been  discussed  in  previous  pages. 


292 


THE  BRAIN. 


pons  Varolii  will,  therefore,  produce  a  paralysis  of  the  cor- 
responding facial  nerve  and  of  the  opposite  spinal  nerves ; 
whereas,  if  it  occur  above  the  point  of  decussation  of  the 
encephalic  fibers,  the  paralysis  will  be  on  the  opposite  side  for 

all  parts  of  the  body.  These 
facts  are  shown  in  the  accom- 
panying diagram  (Fig.  65). 

It  is  obvious,  from  a 
study  of  this  diagram,  that 
a  lesion  of  one  lateral  half 
of  the  pons  (at  I)  will  cause 
paralysis  either  of  motion 
or  of  sensibility  of  the  op- 
posite side  of  the  body,  and 
of  the  corresponding  side  of 
the  face ;  and  that  a  lesion 
of  the  hemisphere  (at  m) 
will  produce  paralysis  of 
the  opposite  side  of  the 
face  and  body. 

As  we  might  naturally 
expect  from  the  direction 
of  the  fibers  of  the  pons 
Varolii,  this  portion  of  the 
brain  acts  as  a  direct  con- 
ductor of  both  motor  and 
sensory  impressions  from 
and  to  the  cerebrum  ;  while 
the  collections  of  gray  mat- 
ter within  its  substance 
prove  it  to  possess  some 
functions  of  its  own  which 
are  independent  of  the  stimulation  of  the  cerebral  cortex. 
Without  entering  into  the  different  experiments  which  have 
been  made  to  determine  the  exact  part  which  this  portion  of 
the  brain  plays  in  the  complex  machinery  of  movement  and 
sensation,  it  seems  probable  that  the  pons  Varolii  regulates 


Fig.  65. — A  diagram  to  illustrate  the  method 
f'produc(io) 
lammond.) 


of  production  of  crossed  paralysis.  (After 
Ha 


a,  the  left  hemisphere ;  b,  right  half  of  pons ; 
c,  right  half  of  medulla  oblongata;  </, 
right  half  of  spinal  cord ;  e,  right  facial 
nerve ;  /,  fiber  of  origin  from  nucleus  in 
medulla  oblongata ;  g^  descending  fiber 
decussating;  at  upper  border  of  pons ;  A, 
ascending  fiber ;  i,  sensory  root  of  spinal 
nerve ;  k,  motor  root  of  sensory  nerve ; 
/,  lesion  in  pons ;  m,  lesion  in  left  hemi- 
sphere ;  n,  paralyzed  part  supplied  by 
facial  nerve;  o,  paralyzed  part  supplied 
by  spinal  nerve. 


FUNCTIONS  OF  PONS  VAROLII.  293 

or  in  some  way  modifies  those  automatic  movements  which 
govern  station  ^ndi  progression. 

The  experiments  of  Yulpian  and  Longet  also  seem  to  sug- 
gest that  the  sensation  of  pain  is  perceived  by  the  pons 
Varolii  even  when  the  cerebrum  and  the  basal  ganglia  are 
removed.  When  these  portions  remain,  such  impulses  are 
probably  transmitted  to  the  hemispheres  as  conscious  sensa- 
tions, and  are  there  remembered. 

These  views  have  been  already  discussed  in  connection 
with  the  functions  of  the  corpora  quadrigemina,  to  which  the 
reader  is  referred. 

General  convulsions  are  peculiarly  apt  to  accompany  sud- 
denly developed  lesions  of  the  pons  (such,  for  example,  as 
embolism  or  a  clot).  These  convulsions  are  generally  followed 
by  coma. 

The  trigeminus  nerve  may  be  paralyzed  by  lesions  of  the 
pons,  provided  the  lesion  lies  within  the  inner  two  thirds 
of  the  reticular  formation  (according  to  the  researches  of 
Starr).  If  such  a  lesion  be  situated  high  up  in  the  pons, 
trigeminal  paralysis  will  coexist  with  hemiansesthesia  of 
the  opposed  half  of  the  body ;  if  situated  low  in  the  pons, 
the  trigeminal  paralysis  and  the  hemiansesthesia  will  be 
upon  the  same  side.  The  point  of  union  of  the  ascending 
and  descending  roots  of  the  fifth  nerve  is  nearly  at  the 
level  at  which  the  fifth  nerve  escapes  from  the  pons  (line 
of  Gubler). 

Difficulties  of  articulation  are  to  be  considered  as  espe- 
cially diagnostic  of  lesions  of  the  pons  or  medulla,  provided 
the  presence  of  aphasia  of  cerebral  origin  can  be  excluded  by 
the  history  of  the  case.  There  is  unquestionably  a  tract  of 
fibers  (the  motor  speech  tract)  that  serves  to  connect  the  nu- 
clei of  the  medulla  with  the  cortical  centers  for  the  move- 
ments of  the  face  and  tongue. 

Conjugate  deviation  of  the  eyes  may  accompany  a  lesion 
of  the  pons.  This  symptom  is  not  pathognomonic,  however, 
because  it  may  occur  also  with  cortical  lesions  of  the  cere- 
brum and  lesions  of  the  internal  capsule. 


294:  THE  BRAIK 

The  motor,  sensory,  and  vaso-motor  effects  of  lesions  with- 
in the  pons  are  manifested  in  the  extremities;  chiefly,  but 
not  exclusively,  upon  the  side  opposed  to  the  lesion.  This  is 
not  the  case  with  those  cranial  nerves  whose  fibers  of  origin 
probably  traverse  the  pons  (the  fifth,  sixth,  seventh,  eighth  [?], 
eleventh  [?],  and  twelfth).  The  effects  of  intrapontine  disease 
upon  these  nerves  are  modified  by  the  seat  of  the  lesion,  as 
has  been  shown  in  preceding  paragraphs. 

Contraction  of  the  pupils  during  an  apoplectic  attack  is 
to  be  regarded  as  strongly  diagnostic  of  a  clot  within  the 
pons. 

HcemorrJiage  into  the  pons  is  usually  followed  by  coma 
and  sudden  death,  if  the  clot  be  large,  or  if  the  blood  escape 
into  the  fourth  ventricle.  The  diagnostic  points  mentioned 
above  apply,  therefore,  more  particularly  to  foci  of  softening 
and  destructive  lesions  of  small  size  and  slow  development. 
When  blood  escapes  into  the  fourth  ventricle,  convulsions  are 
observed,  and  death  is  liable  to  follow  rapidly. 

Disturbances  of  the  circulatory  and  respiratory  func- 
tions may  occur  in  connection  with  lesions  of  the  pons ;  but 
they  are  to  be  regarded  rather  as  evidences  that  the  medulla 
oblongata  is  directly  implicated  or  subjected  to  pressure. 

Deafness  has  been  observed  on  the  same  side  as  the  lesion 
(according  to  Starr)  in  five  out  of  twenty-six  cases  of  reported 
lesions  confined  to  the  pons.  The  auditory  fibers  have  prob- 
ably been  severed  on  their  passage  to  the  nucleus  of  the 
eighth  nerve  through  the  pons. 

FUNCTIONS  OF  THE  MEDULLA  OBLONGATA. 

This  ganglion — the  uppermost  portion  of  the  spinal  cord 
— is  the  true  nerve  centei'  of  animal  life ;  since  immediate 
death  is  apt  to  follow  severe  or  extensive  injury  to  its  sub- 
stance. The  fact  that  the  seventh,  eighth,  ninth,  tenth,  elev- 
enth, and  twelfth  nerves  arise  directly  from  this  ganglion, 
and  that  some  fibers  from  other  of  the  remaining  six  cranial 
nerves  can  be  traced  to  the  cavity  of  the  medulla — the  fourth 


FUNCTTONS  OF  MEDULLA    OBLONGATA.  295 

ventricle — serves  to  explain  the  importance  of  this  special 
nerve  center  to  life. 

In  addition  to  the  special  influence  of  the  medulla  oblon- 
gata upon  the  nerves  which  arise  from  it,  it  contains  also  most 
of  the  fibers  which  are  distributed  to  the  other  parts  of  the 
encephalon,  and  thus  it  must  transmit  both  the  motor  and 
sensory  impulses,  as  they  pass  from  or  enter  the  cerebrum. 

The  medulla  is  possessed  of  a  large  amount  of  gray  matter 
within  its  interior.  It  is  by  means  of  this  gray  matter  that 
the  action  of  the  medulla,  which  is  largely  reflex  in  character, 
takes  place. 

From  the  nerves  which  spring  from  its  substance,  we 
should  expect  that  these  reflex  acts  should  be  chiefly  con- 
cerned in  the  movements  of  the  facial  muscles  by  means  of 
the  seventh  nerve ;  with  audition  by  means  of  the  eighth ; 
with  deglutition  by  means  of  the  ninth  ;  with  respiration 
through  the  pneumogastric  or  tenth  nerve ;  with  phonation 
and  the  action  of  the  heart  by  means  of  the  spinal  accessory ; 
and  with  lingual  movements  by  means  of  the  hypoglossal. 

Various  collections  of  gray  matter  in  the  floor  of  the  fourth 
ventricle  have  been  described  in  previous  pages,  as  connected 
with  special  nerve  roots.  Experimental  investigation  has  also 
determined  that  certain  special  physiological  centers  appar- 
ently have  their  seat  within  the  substance  of  the  medulla 
oblongata. 

The  medulla,  as  a  whole,  serves  (1)  as  a  conductor  of  sen- 
sory impressions^  which  have  passed  along  the  sensory  tracts 
of  the  cord  upward  to  the  cerebrum ;  (2),  as  a  conductor  of 
voluntary  motor  impulses  from  the  cerebrum  to  the  spinal 
cord  and  its  nerves  ;  (3),  as  a  conductor  of  cerebellar  motor 
impulses  to  the  spinal  cord  and  its  nerves,  in  maintaining  a 
tonic  contraction  of  the  skeletal  muscles  ;  and  (4)  as  an  organ 
of  automatic  reflex  action,  governing  all  functions  which  are 
essential  to  life. 

The  centers  for  special  cranial  nerve  roots  have  been  dis- 
cussed already  at  some  length.  A  few  important  deductions 
concerning  them  are  suggested,  however,  by  the  periods  of 


296  THE  BRAIR. 

life  at  which  they  are  developed.  It  is  now  known  that  they 
are  not  all  perfectly  formed  at  the  expiration  of  foetal  life, 
but  are  perfected  later,  as  rapidly  as  the  requirements  of  the 
body  seem  to  demand. 

The  accessory  nucleus  of  the  hypoglossal  nerve  seems  to 
be  an  additional  structure,  which  is  rendered  necessary  in 
order  to  permit  of  the  complicated  movements  that  are  de- 
manded in  the  production  of  articulate  speech. 

The  accessory  facial  nuclei  are  apparently  designed  to 
enable  the  facial  nerve  to  preside  over  the  movements  requi- 
site to  facial  expression  ;  in  contradistinction  to  those  move- 
ments that  are  essential  to  the  functions  of  mastication  and 
respiration,  which  are  probably  controlled  by  the  other  nuclei 
of  that  nerve. 

Two  of  the  four  acoustic  nuclei  are  intimately  associated 
with  the  inferior  and  middle  peduncles  of  the  cerebellum.  It 
is  reasonable,  therefore,  to  infer  that  one  of  them,  at  least,  is 
concerned  in  the  transmission  of  impressions  made  upon  the 
ear  to  the  cerebellum. 

The  importance  of  labyrinthine  impulses  as  a  factor  in  the 
control  which  the  cerebellum  seems  to  possess  over  coordi- 
nated movements  has  been  discussed  in  previous  pages.  * 

Among  the  special  physiological  centers  of  the  medulla, 
the  following  may  be  prominently  mentioned : 

1.  The  respiratory  center^  which  governs  the  respiratory 
acts,  in  response  to  sensory  impressions  transmitted  to  it  by 
means  of  the  centripetal  fibers  of  the  pneumogastric  nerve. 
This  center  also  presides  over  the  acts  of  laughing^  sigh- 
ing^ sobbing^  sneezing^  and  hiccough^  which  are  performed 
by  the  muscles  of  respiration.  It  is  excited  by  the  irritation 
of  carbonic  acid  upon  the  terminal  filaments  of  the  pneumo- 
gastric nerve  in  the  lung,  or  by  its  presence  in  the  blood.  An 
excess  of  it  increases  the  respirations,  while  an  excess  of  oxy- 
gen tends  to  decrease  their  frequency. 

2.  The  vaso-motor  center^  which  seems  to  control  the  cali- 
ber of  the  larger  blood-vessels,  by  means  of  efferent  impulses, 
transmitted  first  down  the  spinal  cord,  next  through  the  ante- 


PHYSIOLOGICAL  CENTERS  OF  MEDULLA.  297 

rior  roots  of  the  dorsal  nerves,  and  then  chiefly  through  the 
splanchnic  nerves.  They  affect  the  muscular  coat  of  the  ves- 
sels of  the  thorax,  abdomen,  and  pelvis.  The  upper  limit  of 
this  center  in  the  rabbit  is  placed  by  Owsjannikow  (Ludwig's 
"  Arbeitem,"  1871)  at  about  two  mm.  below  the  tubercula  quad- 
rigemina,  and  its  lower  limit  at  about  four  or  five  mm.  above 
the  calamus  scriptorius.  Clarke  locates  it  near  to  the  origin 
of  the  facial  nerve,  and  claims  that  large  multipolar  cells  can 
be  detected  in  the  vaso-motor  area  ;  while  Dittmar  (Ludwig's 
"Arbeitem,"  1873)  places  it  chiefly  in  the  lateral  columns, 
after  the  fibers  have  been  given  off  to  the  decussating  pyra- 
mids. Besides  this  vaso-motor  center  in  the  medulla  oblon- 
gata, some  parts  of  the  spinal  gray  matter  unquestionably 
exert  a  positive  vaso-motor  influence,  causing  constriction  or 
dilatation  of  the  blood-vessels. 

3.  The  Cardio-InMMtory  Center. — By  it  the  heart  is 
arrested  in  diastole,  or  held  under  control,  in  response  to 
sensory  impressions  carried  to  the  medulla  from  other  sources 
by  means  of  sensory  nerves.  If  the  mesentery  of  a  frog  be 
exposed,  and  a  slight  tap  be  given  it  by  the  handle  of  the 
scalpel,  the  heart  will  at  once  cease  to  beat,  but  will  soon  re- 
sume its  function.  This  experiment,  coupled  with  many 
others  of  interest,  seems  to  point  definitely  to  the  medulla  as 
the  seat  of  mediation  between  afferent  sensory  impulses  and 
efferent  inhibitory  impulses  upon  the  heart. 

4.  The  Center  for  Deglutition.— Thi^  controls  both  the 
second  and  third  stages  of  that  act,  or  from  the  time  when 
the  bolus  passes  the  isthmus  of  the  fauces.  This  subject  will 
be  found  discussed,  at  some  length,  in  the  pages  devoted  to 
the  mechanism  of  deglutition,  as  well  as  the  movements  of 
the  oesophagus. 

5.  The  center  for  the  movements  of  the  oesophagus  and 
the  stomach,  with  its  allied- center  for  the  control  of  the 
mechanism  of  the  act  of  vomiting. 

6.  The  Diabetic  Center.— This  center,  when  stimulated, 
produces  a  saccharine  condition  of  the  urine.  The  diabetic 
center,  as  marked  out  by  Eckhard,   corresponds  closely  to 


298  THE  BRAIN. 

that  defined  by  Owsjannikow  as  the  vaso-motor  area.  Prick- 
ing of  this  center  in  a  well-fed  rabbit  will  produce  a  consid- 
erable amount  of  sugar  in  the  urine,  within  an  hour  or  two 
following  the  experiment.  This  effect  is  poorly  marked  in 
animals  whose  livers  have  been  deprived  of  glycogen  by 
starvation. 

7.  The  Salinary  Center. — This,  upon  excitation,  tends  to 
increase  the  flow  of  the  saliva,  and  possibly,  also,  the  pancre- 
atic fluid  and  the  other  digestive  juices.  The  flow  of  saliva  is 
apparently  a  reflex  act  dependent  upon  afferent  impulses 
perceived  through  the  gustatory  branch  of  the  fifth  cranial 
nerve,  the  efferent  impulse  being  transmitted  by  means  of  the 
chorda  tympani  branch  of  the  facial  nerve.  It  is  this  func- 
tion of  the  latter  nerve  that  is  considered  by  some  physiolo- 
gists as  explanatory  of  the  effect  of  the  chorda  upon  taste. 
(See  pages  descriptive  of  the  facial  nerve  and  its  branches.) 

8.  The  convulsive  center^  first  described  by  Nothnagel,  is 
probably  associated  in  an  imperfectly  understood  way  with 
the  motor  tracts  that  are  found  within  the  medulla.  It  is 
closely  allied  to  the  respiratory  center,  as  is  proved  by  the 
convulsions  which  occur  in  consequence  of  carbonic-acid  poi- 
soning, or  when  the  supply  of  blood  to  the  medulla  is  sud- 
denly cut  off  after  the  ligation  of  a  large  vessel. 

9.  A  cardio-acceleratory  center,  which  exercises  the  power 
of  increasing  the  frequency  of  the  pulse  by  means  of  fibers 
which  pass  downward  into  the  cervical  region  of  the  spinal 
cord ;  they  emerge  to  enter  the  inferior  cervical  ganglion  of 
the  sympathetic  upon  either  side  of  the  spinal  column,  thence 
passing  to  the  heart. 

By  means  of  these  physiological  centers  the  medulla  is 
enabled  to  exercise  a  modifying  or  controlling  infiuence  over 
the  more  important  organs  of  the  body.  In  every  case,  it  is 
informed  by  excitor  or  centripetal  nerves  of  the  requirements 
of  the  various  regions  which  are  essential  to  the  performance 
of  their  respective  functions ;  and  by  motor  or  centrifugal 
nerves,  or,  in  some  instances,  by  its  influence  upon  the  nerves 
of  the  vaso-motor  system,  the  proper  responses  to  these  im- 


NERVOUS  CIRCLE  OF  DEGLUTITION  299 

pressions  (telegraphed  to  it  by  the  sensory  nerves)  are  sent 
out.     This  constitutes  what  is  termed  "reflex  action." 

In  the  second  and  third  stages  of  the  act  of  deglutition, 
for  example,  the  medulla  is  thrown  into  excitation  by  means 
of  the  following  nerve-trunks  : 

1.  The  branches  of  the  trigeminus  distributed  to  the 
palate. 

2.  The  pharyngeal  branches  of  the  glosso  -  pharyngeal 
nerve. 

3.  The  oesophageal  and  superior  laryngeal  branches  of  the 
pneumogastric  nerve. 

Its  motor  responses  are  then  made  through  the  aid  of  the 
following  nerves : 

1.  The  pharyngeal  branches  of  the  pneumogastric,  derived 
from  the  spinal  accessory  nerve. 

2.  The  hypoglossal  nerve. 

3.  The  motor  filaments  of  the  inferior  maxillary  nerve. 

4.  The  facial  nerve. 

5.  Branches  of  the  cervical  plexus. 

These  centripetal  and  centrifugal  sets  of  nerves,  with  the 
so-called  ''center"  which  intervenes,  constitute  collectively 
what  has  been  termed  the  ''nervous  circle^^  of  the  act  of  deg- 
lutition. Similar  ''nervous  circles"  are  associated  with  each 
of  the  more  important  functions  that  are  of  a  purely  reflex 
type,  such  as  the  act  of  respiration,  the  pulsation  of  the 
heart,  etc. 

When  the  ganglia  of  the  brain  above  the  level  of  the  me- 
dulla are  all  removed,  animals  will  continue  to  live  and 
breathe.  Those  regions  which  are  supplied  by  the  nerves 
that  are  associated  with  the  gray  nuclei  of  the  medulla,  as 
well  as  those  supplied  by  the  spinal  nerves,  will,  however, 
still  exhibit  reflex  phenomena  when  subjected  to  irritation. 
If  the  conjunctiva  be  touched,  the  eyelids  will  close.  Con- 
traction of  the  muscles  of  the  face,  movements  of  the  tongue, 
and  twitching  of  the  ears,  can  also  be  artificially  produced 
by  irritation  of  the  sensory  nerves  distributed  to  those  re- 
gions. 


300  THE  BR  A  IK 

In  addition  to  these  evidences  of  simple  reflex  action, 
more  complicated  movements  that  require  cobrdination  of 
different  sets  of  muscles  can  also  be  elicited.  In  an  animal 
so  mutilated,  the  acts. of  sucking  and  of  deglutition  can  be 
performed  with  as  great  precision  as  in  health.  These  can  be 
excited  by  the  introduction  of  a  morsel  of  food  into  the 
mouth  so  as  to  rest  upon  the  back  of  the  tongue,  or  the  inser- 
tion of  a  nipple  between  the  lips  of  a  younger  animal.  We 
also  observe  these  phenomena  in  those  rare  cases  of  living 
anencephalic  children,  who  nurse  at  the  breast  as  perfectly 
as  perfectly-developed  offspring. 

The  fact  that  a  subsequent  destruction  of  the  medulla 
causes  instant  annihilation  of  these  reflex  and  coordinated 
movements  seems  to  be  a  most  positive  proof  that  the  me- 
dulla can  be  regarded  both  as  a  center  of  reflex  action  and  as 
one  also  of  coordination. 

Clinical  evidences  that  the  medulla  acts  as  a  coordinating 
center  for  the  complex  movements   required  in  articulate  \ 
speech  are  afforded  in  the  disease  known  as  "  glosso-laMo-  j 
laryngeal  jparalysis^^''   first    described    by    Duchenne,   and  i 
hence  often  spoken  of  as  *'Duchenne's  disease."    In  this  con-  ■ 
dition  the  nuclei  of  the  medulla  that  are  connected  with  the  ; 
hypoglossal,  facial,  glosso-pharyngeal,  and  spinal-accessory  j 
neiTes  undergo  progressive  degeneration  ;   hence,  the  term  ; 
'''bulbar  paralysis^^  is  often  employed  in  place  of  the  others  ! 
previously  mentioned.     The  effects  of  this  degeneration  are 
manifested  in  a  gradual  and  progressive  paralysis  of  the 
tongue,  lips,  palate,  pharynx,  and  larynx,  which  renders  ar- 
ticulation, deglutition,  and  phonation  more  or  less  imperfect, 
and  at  the  same  time  causes  an  alteration  in  the  expression 
of  the  face  that  is  not  easily  mistaken.     (See  subsequent 
pages,  which  treat  more  fully  of  its  symptoms.) 

Some  authorities  have  advanced  the  view  that  the  olivary 
bodies  are  the  probable  coordinating  centers  of  articulation ; 
but  this  appears  to  be  an  error,  because  those  bodies  are  more 
intimately  connected  with  the  inferior  peduncles  of  the  cere- 
bellum.    A  remarkable  case  reported  by  Yulpian,  in  which 


RESPIRATORY  MECEAmSM  OF  MEDULLA,  301 

the  olivary  bodies  were  completely  degenerated,  was  found  to 
exhibit  no  impairment  of  speech. 

The  relation  of  the  medulla  to  facial  expkession"  is  one 
of  great  interest,  if  it  can  be  positively  verified.  Yuli:)ian  be- 
lieved that  his  experiments  made  upon  the  rat  demonstrated 
the  relation  of  all  forms  of  emotional  expression,  such  as  cries 
and  facial  contortions,  with  the  centers  of  the  medulla.  These 
experiments  have  been  differently  interpreted,  however,  by 
some  later  investigators  in  the  same  line.  Ferrier  thinks  that 
the  cry  of  animals  which  follows  a  painful  impression  made 
upon  the  extremities,  after  the  encephalic  centers  above  the 
medulla  have  been  removed,  is  to  be  regarded  simply  as  a 
variety  of  respiration  i-ather  than  an  evidence  of  the  sen- 
sation of  pain — a  view  which  is  consistent  with  the  chief 
function  of  that  ganglion.  This  will  now  be  separately  con- 
sidered. 

The  RESPiRATOEY  MECHAi^iSM  is  Unquestionably  presided 
over  by  the  medulla.  Flourens  has  devoted  special  attention 
toward  the  results  of  experiments,  made  upon  the  medulla  of 
animals,  in  respect  to  their  effects  upon  respiration.  He 
places  its  situation  at  the  apex  of  the  fourth  ventricle  near  to 
the  calamus  scriptorius — a  point  which  he  terms  the  ''noeud- 
vital.^^ 

This  center  receives  the  following  excitor  or  centripetal 
nerve  fibers : 

1.  The  pulmonary  branches  of  the  vagus  nerve. 

2.  The  superior  laryngeal  branches  of  the  vagus  nerve. 

3.  The  sensory  fibers  of  the  trigeminus  nerve. 

4.  The  nerves  of  general  sensibility  of  the  trunk  and  ex- 
tremities. 

5.  The  sympathetic  nerve. 

These  various  sources  of  sensory  impressions  enable  the 
respiratory  center  of  the  medulla  to  so  coordinate  the  muscles 
of  respiration  as  to  insure  the  proper  performance  and  rela- 
tive frequency  of  the  inspiratory  and  expiratory  acts,  as  the 
amount  of  exercise  and  the  demands  of  the  body  seem  to 
require. 

22 


302  THE  BRAIN. 

The  nerves  through  which  the  centrifugal  or  motor  im- 
pulses are  transmitted,  in  response  to  these  sensory  impres- 
sions, may  be  thus  enumerated  : 

1.  The  phrenic  nerve,  by  fibers  which  traverse  the  spinal 
cord  as  far  as  the  level  of  the  third  dorsal  nerves. 

2.  The  intercostal  nerves,  which  are  given  off  from  the 
dorsal  region  of  the  spinal  cord. 

3.  The  facial  nerve,  which  governs  the  movements  of  the 
nostrils  during  inspiration. 

4.  The  external  branch  of  the  spinal  accessory  nerve, 
which  supplies  the  sterno-mastoid  and  trapezius. 

6.  The  inferior  laryngeal  branch  of  the  pneumogastric 
nerve,  which  governs  the  movements  of  the  glottis. 

6.  Filaments  of  the  cervical  plexus,  which  assist  the  scla- 
nei  muscles  to  fix  the  first  rib  during  inspiration. 

The  respiratory  act  is  under  the  control  of  tlie  will  to  a 
limited  extent,  in  order  to  allow  of  speech,  vocalization,  and 
the  expulsion  of  the  contents  of  the  uterus,  bladder,  and  rec- 
tum. When  this  voluntary  control  is  carried  beyond  its 
proper  limits,  it  becomes  lost,  as  the  desire  for  respiration 
becomes  too  great  to  be  controlled. 

We  have  referred  in  a  previous  page  to  the  acts  of  cougli- 
ing^  sighing,  sobbing^  laughing,  sneezing,  and  hiccough  as 
modifications  of  the  respiratory  act.  They  are  presided  over 
by  the  respiratory  center. 

The  rhythmical  alternation  of  expiratory  and  inspiratory 
movements  is  not  due  entirely  to  reflex  action.  The  amount 
of  carbonic  acid  in  the  blood  modifies  the  action  of  the  re- 
spiratory center  as  well  as  sensory  impressions  carried  to  it 
by  means  of  nerves.  This  point  has  been  previously  touched 
upon. 

The  course  of  the  respiratory  tract  of  nerves  within  the 
spinal  cord  has  been  made  a  subject  of  investigation  by  Schiff, 
Vulpian,  Brown- Sequard,  and  others.  The  views  of  these 
observers  are  somewhat  contradictory.  It  is  probable  that 
they  run  in  the  gray  substance  of  the  cord  rather  than  in  the 
lateral  columns,  as  Schiff  was  led  to  infer. 


CARDIAC  CENTERS  OF  MEDULLA. 

Long  after  the  reflex  excitability  of  the  spinal  cord  has 
ceased,  and  even  after  all  voluntary  or  conscious  actions  have 
been  abolished,  the  respiratory  center  retains  its  activity. 
This  is  admirably  demonstrated  in  the  administration  of  anses- 
thetics,  which,  when  pushed  to  their  fullest  extent  in  animals, 
paralyze  the  brain  and  spinal  cord  before  the  respiratory  cen- 
ters succumb. 

The  CARDIAC  CEisTTEES  withiu  the  substance  of  the  medulla 
seem  to  be  connected  with  nerves  which  have  opposite  func- 
tions, one  accelerating  the  pulse  and  the  other  inhibiting  or 
restraining  the  action  of  the  heart. 

The  rhythmical  action  of  the  heart  is  in  no  way  connected 
with  the  centers  of  the  medulla,  as  that  organ  will  continue  to 
beat  long  after  it  is  completely  severed  from  its  connections 
with  the  brain  or  spinal  cord.  It  seems  to  be  controlled  by 
the  ganglia  of  the  heart  itself  (Bidder  and  Remak's  ganglia). 
The  medulla  appears  to  act  simply  as  a  governor  of  the  heart's 
action. 

The  inhibitory  nerves  connected  with  the  cardio-inhibi- 
tory  center  pass  from  the  medulla  to  the  heart  chiefly  by 
means  of  the  vagus ;  hence,  section  of  the  vagus  causes  an 
acceleration  of  the  heart's  action,  because  it  is  no  longer  re- 
strained by  these  fibers.  Powerful  irritation  of  the  sensory 
nerves  of  the  stomach  or  intestine,  the  nostrils,  or  the  larynx 
causes  a  stimulation  of  these  fibers  which  may  arrest  the 
action  of  the  heart.  This  may  help  to  explain  the  fatal  re- 
sults of  a  blow  received  upon  the  epigastric  region,  or  the 
shock  of  a  large  draught  of  cold  water  or  of  an  irritant  poison 
upon  the  sensory  nerves  of  the  stomach  (Ferrier). 

The  acceleratory  nerves  connected  with  the  cardio-accel- 
eratory  center  pass  down  the  cervical  region  of  the  spinal 
cord,  and  escape  to  enter  the  inferior  cervical  or  first  dorsal 
ganglion  of  the  sympathetic.  From  these  ganglia  they  are 
prolonged  to  the  heart,  upon  either  side,  as  filaments  of  the 
cardiac  nerves.  They  can  be  reflexly  excited  by  a  stimulus 
applied  to  the  sensory  nerves  distributed  to  the  muscular 
system.     Ferrier  suggests  that  this  fact  may  help  to  explain 


304  THE  BRAIN. 

the  rapidity  of  the  heart's  action  during  active  muscular 
exercise. 

The  existence  of  a  vaso-motor  center  within  the  human 
medulla,  as  has  been  proven  to  exist  in  animals,  is  confirmed 
by  pathological  observation.  Subjective  sensations  of  heat  and 
cold  in  the  limbs  have  been  found  to  exist  in  connection  with 
a  lesion  of  the  upper  half  of  the  medulla.  The  area  occu- 
pied by  this  center  in  man  therefore  corresponds  to  that  of 
animals  (as  determined  by  Foster),  viz.,  slightly  above  the 
calamus  scriptorius. 

The  vaso-motor  center  within  the  substance  of  the  medulla 
controls  the  innervation  of  blood-vessels.  It  is  connected 
with  afferent  as  well  as  efferent  fibers.  The  former  tend 
rather  to  excite  or  depress  the  activity  of  this  center,  and  thus 
in  a  reflex  way  to  cause  contraction  or  dilatation  of  the  blood- 
vessels. 

The  vaso-motor  nerves  pass,  by  means  of  the  substance  of 
the  spinal  cord,  to  various  ganglia  of  the  sympathetic  system 
and  thence  to  the  coats  of  the  arteries.  They  tend  to  main- 
tain a  state  of  tonic  contraction  of  the  arterial  walls.  This 
has  been  termed  by  physiologists  "arterial  tonus. "^"^  It  has 
been  found  that,  when  the  spinal  cord  is  divided  below 
the  level  of  the  medulla,  this  arterial  tonus  is  destroyed,  a 
dilatation  of  the  arteries  immediately  taking  place.  A  sec- 
tion of  the  sympathetic  nerve  or  of  cerebro-spinal  nerves 
which  convey  its  fibers  to  certain  blood-vessels  produces  a 
similar  result,  in  regions  more  or  less  circumscribed  according 
to  the  nerve  trunk  which  is  severed. 

The  ''arterial  tonus"  is  controlled,  however,  in  part  by  the 
spinal  cord,  irrespective  of  the  medulla  oblongata.  This  fact 
was  first  pointed  out  by  Yulpian,  who  found  that,  after  sec- 
tion of  the  spinal  cord  below  the  medulla,  a  complete  destruc- 
tion of  the  cord  or  a  division  of  the  anterior  spinal  nerve 
roots  increased  the  dilatation  of  the  blood-vessels. 

The  vaso-motor  center  of  the  medulla  is  stimulated  by  ir- 
ritation of  any  sensory  nerve  of  the  body,  as  is  demonstrated 
by  the  general  contraction  of  the  blood-vessels  which  follows. 


VASO-MOTOR   CENTER   OF  MEDULLA.  305 

It  is  somewhat  remarkable,  however,  that  along  with  this 
general  excitation  there  appears  to  be  a  local  diminution  of 
the  *' arterial  tonus,"  so  that  the  blood-vessels  of  the  part 
which  is  directly  irritated  become  dilated  and  the  skin  mark- 
edly reddened. 

The  activity  of  the  vaso-motor  center  of  the  medulla  ap- 
pears to  be  decreased  when  one  of  the  branches  of  the  pneu- 
mogastric  nerve,  which  is  sent  to  the  heart,  is  irritated.  This 
is  described  in  a  subsequent  chapter  as  the  "depressor  nerxe?'' 
It  tends  to  greatly  diminish  the  blood-pressure  by  causing  a 
cessation  of  the  arterial  tonus.  Ferrier  is  inclined  to  believe 
that  a  distended  state  of  the  ventricles,  when  associated  with 
a  labored  heart's  action,  creates  a  stimulation  of  this  nerve 
and  thus  brings  relief  by  inducing  a  dilated  condition  of  the 
vessels  and  a  diminution  of  the  tension. 

The  relations  of  the  force  of  the  heart-heat  to  the  blood- 
pressure  within  the  arteries  seem  to  be  governed  by  the  vaso- 
motor center  of  the  medulla  and  the  nerve  fibers  associated 
with  it.  As  the  arteries  contract,  the  blood-pressure  necessa- 
rily rises  and  is  then  apparently  compensated  by  a  slowing 
of  the  action  of  the  heart.  On  the  other  hand,  when  the 
arteries  become  excessively  dilated,  the  blood-pressure  falls 
and  the  heart  is  thrown  into  a  state  of  increased  activity. 

Again,  the  vaso-motor  center  and  the  center  of  respira- 
tion apparently  exhihit  reciprocal  relations.  During  each 
inspiration,  the  pulse  becomes  somewhat  accelerated;  and, 
during  expiration,  it  is  diminished  in  frequency.  These 
oscillations  are  now  believed  to  be  independent  of  variations 
in  the  blood-pressure  which  are  produced  by  the  tendency 
toward  a  vacuum  in  the  chest  as  the  diaphragm  descends. 

Ferrier  thus  summarizes  the  reflex  functions  of  the  me- 
dulla :  ''  The  medulla  oblongata  is  thus  a  coordinating  center 
of  reflex  actions  essential  to  the  maintenance  of  life.  If  all 
the  centers  above  the  medulla  be  removed,  life  may  continue, 
the  respiratory  movements  may  go  on  with  their  accustomed 
rhythm,  the  heart  may  continue  to  beat,  and  the  circulation  be 
maintained  ;  the  animal  may  swallow  if  food  be  introduced 


306  THE  BRAIK 

into  the  mouth,  may  react  to  impressions  made  on  its  sensory- 
nerves,  withdrawing  its  limbs  or  making  an  irregular  spring 
if  pinched,  or  even  utter  a  cry  as  if  in  pain,  and  yet  will  be 
merely  a  non-sentient,  non -intelligent,  reflex  mechanism." 


DIAGNOSTIC    SYMPTOMS    OF  LESIONS    OF  THE   MEDULLA 
OBLONGATA. 

The  size  of  this  ganglion  almost  precludes  the  existence  of 
lesions,  even  if  small,  which  do  not  influence  to  a  greater  or 
less  extent  the  nerve  nuclei  contained  within  it. 

An  implication  of  the  cranial  nerve-roots  (Figs.  6b  and  56) 
may  cause  disturbances  of  respiration,  circulation,  phonation, 
deglutition,  and  articulation. 

The  sensory  and  motor  tracts  to  the  extremities  may  be 
simultaneously  involved,  and  thus  anaesthesia  (?)  and  paralysis 
of  motion  may  occur  upon  the  side  of  the  body  opposed  to 
the  lesion.  The  fillet  tract  may  be  also  affected  by  the  lesion, 
in  which  case  evidences  of  unilateral  ataxia  will  be  developed 
in  the  extremities.  Finally,  the  lower  part  of  the  face  may 
be  rendered  paretic. 

Of  the  above-mentioned  symptoms,  aphonia  and  the  im- 
pairment of  the  respiratory  and  circulatory  symptoms  are 
particularly  diagnostic  of  medullary  lesions. 

The  symptoms  of  Duchenne's  disease  are  present  only 
when  chronic  progressive  degeneration  of  the  nuclei  of  the 
medulla  exists. 

Suddenly  developed  lesions  of  the  medulla  are  liable  to 
cause  instantaneous  death. 

Diabetes  and  albuminuria  may  be  excited  by  lesions  of 
the  medulla. 

When  the  pneumogastric  nerves  are  implicated,  dyspnoea, 
irregularity  of  the  action  of  the  heart,  and  gastric  or  intes- 
tinal derangements  are  encountered. 

In  a  few  instances,  tumors  and  foci  of  softening  in  the  me- 
dulla have  been  known  to  exist  and  create  no  symptoms  of  a 
diagnostic  character. 


SYMPTOMS  OF  LESIONS  OF  MEDULLA.  307 

Dysphasia^  and  the  loss  of  tlie  power  of  protrusion  oftlie 
tongue,  point  to  an  implication  of  the  hypoglossal  and  glosso- 
pharyngeal nuclei. 

A  lesion  of  one  anterior  pyramid  would  cause  a  paralysis 
of  motion  in  the  opposite  arm  and  leg. 

A  lesion  of  both  anterior  pyramids,  or  one  in  the  median 
line  of  the  medulla,  so  low  as  to  involve  the  decussation  of 
the  "crossed  pyramidal  tracts,"  would  cause  a  paralysis  of 
motion  in  both  arms  and  both  legs. 

A  lesion  of  the  lemniscus  or  fillet  tract,  in  any  part  of  its 
course,  would  create  a  unilateral  loss  of  coordination  of  the 
upper  and  lower  extremities  of  the  opposite  side. 

A  lesion  which  involves  the  i^aso-motor  center  of  either 
side  in  the  medulla  would  cause  a  general  unilateral  redness, 
abnormal  heat,  and  profuse  sweating  on  the  same  side  of  the 
body  as  the  lesion. 

THE   VENTRICLES   OF  THE  BRAIN. 

The  method  of  development  of  the  brain  teaches  us  that 
the  cavities  found  within  its  substance  are  the  evidences  of  its 
early  tubular  formation.  The  simplest  forms  of  brains  show 
that  the  primitive  medullary  tube  becomes  constricted  in  such 
a  way  as  to  form  three  vesicles,  which  go  to  form  the  cere- 
brum, the  corpora  quadrigemina,  and  the  medulla  oblongata 
of  the  human  brain.  In  a  general  way,  it  may  be  said  that 
the  anterior  vesicle  subsequently  develops,  in  the  human 
subject,  into  the  cerebral  hemispheres,  the  basal  ganglia,  the 
olfactory  lobes,  and  the  lateral  and  third  ventricles.'  The 
middle  vesicle  yields  the  crus  of  each  hemisphere,  as  far  as 
the  pons  Varolii  and  the  aqueduct  of  Sylvius,  or  the  commu- 
nicating passage  between  the  third  and  fourth  ventricles.  The 
^hird  vesicle  forms  the  medulla  oblongata,  the  cavity  of  the 
fourth  ventricle,  the  cerebellum,  and  the  pons  Varolii.  The  so- 
Llled  "fifth  ventricle"  of  descriptive  anatomists  can  not  prop- 
erly be  said  to  form  a  part  of  the  primitive  tube  (Wilder). 

*  Wilder  applies  the  term  "  coelite  "  to  the  ventricular  cavities. 


308  THE  BEAIK 

The  expansion  of  the  anterior  vesicle  into  the  cerebral 
hemispheres,  with  its  component  ganglia  and  connecting 
fibers,  causes  each  hemisphere,  the  corpus  callosum,  the  cau- 
date nucleus  of  the  corpus  striatum,  the  fornix,  and  the  thala- 
mus to  assume  an  arch-like  form,  whose  buttresses  approach 
each  other  in  the  region  of  the  floor  of  the  cranial  cavity. 

Although  the  ventricles  originally  appear  as  tubular  cavi- 
ties in  the  process  of  development,  they  soon  become  modified 
as  to  configuration  by  the  development  of  adjacent  structures. 
In  the  fully  formed  brain  of  the  human  subject  the  central 
canal  of  the  cord  and  its  continuation  into  the  mesencephalon 
(the  iter  or  ''aqueduct  of  Sylvius")  remain  tubular.  The 
other  expansions  of  the  primitive  tube  are  more  or  less  modi- 
fied. 

Pathological  changes  are  not  infrequently  observed  in  the 
ventricles,  their  size  being  often  increased.  In  old  or  debili- 
tated subjects  the  posterior  cornua  of  the  lateral  ventricles  are 
rendered  funnel-shaped  by  the  gravitation  of  the  cerebro- 
spinal fiuid,  provided  that  a  long- continued  confinement  to 
bed  has  been  required.  Flower  has  observed  an  obliteration 
(more  or  less  complete)  of  the  hippocampus  major  from  this 
cause,  accompanied  by  changes  in  the  occipital  lobes. 

The  Lateral  Ventricles.— These  are  two  large  cavities 
in  the  substance  of  the  cerebrum,  one  in  each  hemisphere. 
They  lie  on  a  higher  plane  than  the  third  ventricle,  being 
roofed  in  by  the  corpus  callosum.  On  the  floor  of  each  may 
be  seen  the  caudate  nucleus  of  the  corpus  striatum,  the  ante- 
rior tubercle  of  the  thalamus,  the  taenia  semicircularis  sepa- 
rating these  ganglia,  a  portion  of  the  fornix,  and  a  plexus  of 
vessels  derived  from  the  pia  mater,  called  the  "  choroid  plex- 
us." Each  lateral  ventricle  is  lined  with  a  delicate  layer 
called  the  ''' ependyma^^—th^it  is,  covered  with  cilia  in  the 
foetus.  From  the  central  or  main  cavity  of  the  lateral  ventri- 
cle of  each  side  three  prolongations,  called  ''cornua,"  are  to 
be  observed.  These  are  named  from  before  backward,  the 
anterior,  the  middle  or  descending,  and  the  posterior.  The 
lateral  ventricles  are  separated  from  each  other  by  the  so- 


Special  Cortical  Motor  Areas  of  the  Human  Subject. 

(According  to  observations  of  Horsley.) 


Upper  part  of  face  and  the  angle  of  the  mouth 
on  the  opposed  side. 


Adduction  of  the  vocal  cords. 


Lower  part  of  face  and  floor  of  the  mouth  of  opposed  side. 


The  slioulder  of  the  opposed  side. 


The  elbow  and  wrist  of  the  opposed  side. 


Special  Cortical  Motor  Areas  of  the  Human  Subject. 

(According  to  observations  of  Ilorsley  and  Beevor.) 


Area  for  the  thumb.     (Horsley.) 


Combined  synchronous  movements  of  both 
limbs.     (Horsley.) 


he  lower  limb.      H.  Area  for  the  big  toe  in      Area  for  movements  of  the  head  and  neck,  to-      | 
the  para-central  lobule.     (Beevor  and  Ilors-  gether  with  conjugate  deviation  of  the  eyes.       j 

ley.)  (Horsley.)  j 


TEE  LATERAL    VENTRICLES. 


309 


called  '' septum  lucidum,"  that  consists  of  two  laminae.  Be- 
tween these  two  laminae  the  so-called  ''fifth  ventricle"  is 
situated. 


Fig.  66. —  View  from  above  of  the  third  ventricle  and  a  part  of  the  lateral  ventricles. 

(Henle.) 

The  brain  has  been  sliced  horizontally,  immediately  below  the  corpus  callosum,  and  the 
fornix  and  velum  interpositum  have  been  removed.  Tho,  thalamus  opticus ;  Ts,  its 
anterior  tubercle;  Pv,  pulvinar;  Com,  middle  commissure  stretching  between  the 
two  optic  thalami  across  the  middle  of  the  third  ventricle ;  Cf,  columns  of  the  for- 
nix ;  Cn,  pineal  p^land  projecting  downward  and  backward  between  the  superior  cor- 
pora quadrigemina ;  Sf,  stria  terminalis;  Cs,  nucleus  caudatus  of  the  corpus  stria- 
tum ;  Vsl,  ventricle  of  the  septum  lucidum ;  Ccl^,  section  of  the  genu  of  the  corpus 
callosum ;  Pen,  commencement  of  the  pineal  stria  or  peduncle,  Tfo ;  Cop,  posterior 
commissure. 


The  lateral  ventricles  communicate  with  each  other  and 
with  the  third  ventricle  by  means  of  two  openings  behind  the 


310  THE  BRAIK  j 

anterior  pillars  of  the  fornix  (Fig.  67),  known  as  the  ''for a-  ' 
mina  of  Monroe  In  chronic  hydrocephalus,  when  the  ven-  i 
tricles  are  excessively  distended  by  fluid,  these  openings  are  | 
greatly  enlarged,  and  may  occasionally  admit  the  point  of  a  i 
finger.  \ 

The  anterior  horn  of  each  lateral  ventricle  is  produced  by  ; 
the  development  of  the  caudate  nucleus.  It  curves  around  its  '. 
anterior  extremity,  and  projects  into  the  frontal  lobe.  ; 

The  middle  or  descending  Jiorn  takes  an  irregularly  curved 
course — compared  by  some  anatomists  to  that  of  a  ram's  horn  i 
— around  the  optic  thalamus,  and  extends  into  the  temporo-  ■ 
sphenoidal  lobe  as  far  as  its  tip.  On  its  floor  may  be  seen  an  \ 
eminence  known  as  the  "hippocampus  major^^^  which  termi-  -i 
nates  in  two  or  three  finger-like  processes,  called  the  "pes  | 
hippocampi. '^^  The  sharp  edge  of  the  fornix  and  a  fold  of  the  i 
choroid  plexus  may  also  be  discerned  here.  ; 

The  posterior  horn  is  small  and  extends  into  the  occipital  ' 
lobe.  It  contains,  as  in  the  case  of  the  middle  horn,  an  ellip-  ' 
tical  elevation,  called  the  "hippocampus  mmo7',"and  its  digi-  , 
tated  extremity,  the  "pes  accessor ius,^^  ■ 

The  '^calcarine"  and  ''collateral  fissures"  of  the  surface  \ 
of  the  cerebrum  are  anatomically  associated  with  the  hippo-  J 
campal  eminences,  as  has  been  mentioned  in  a  previous  page.   ' 

It  may,  perhaps,  help  the  reader,  in  forming  a  proper  con-  ; 
ception  of  the  relations  of  the  ventricles  to  each  other  and  to  ; 
adjacent  structures,  to  compare  them  to  chambers  in  different  . 
stories  of  a  house.  From  such  a  homely  simile  the  two  lateral 
and  fifth  ventricles  might  be  compared  to  the  attic  chambers,  I 
the  third  ventricle  would  be  a  chamber  on  the  floor  below,  and  \ 
the  fourth  ventricle  a  room  on  a  floor  still  low^er  down.  Each  ^ 
lateral  ventricle  lies  above  the  level  of  the  basal  ganglia^  since  j 
these  ganglia  appear  to  a  slight  extent  upon  its  floor.  The  \ 
third  ventricle  lies  in  the  mesial  plane  of  the  brain,  between  \ 
the  optic  thalamic  and  extends  downward  as  far  as  the  floor  - 
of  the  cerebrum.  Finally,  the  fourth  ventricle  lies  in  the  j 
region  of  the  medulla  oblongata^  entirely  below  all  relation  ; 
with  the  cerebral  hemispheres.  j 

I 


RELATIONS  OF  THE   VENTRICLES, 


311 


Now,  all  of  these  cavities  communicate  and  form  in  reality 
a  continuous  cavity,  with  constrictions  in  caliber  here  and 
there,  and  large  expansions  in  other  places.     The  cerebro- 


s.L. 


o.c 


Limits  of 
the  medulla 
end  pons. 


Canal  of  spinal  cord. 


spinal  fluid  is  thus  enabled  to  flow  continuously  from  below 
upward  till  it  fills  the  lateral  ventricles,  as  well  as  the  third 
and  fourth,  and  to  be  forced  out  again  when  an  excess  of  blood 
in  the  cerebral  vessels  demands  a  decrease  of  the  intra- ven- 
tricular pressure.  This  subject  will  be  more  fully  discussed 
in  connection  with  the  membranes  of  the  spinal  cord. 

The  lateral  ventricles  are  best  exposed  by  separating  the 
cerebral  hemispheres  from  each  other,  and  then  dividing  the 
corpus  callosum,  upon  either  side  of  the  median  line,  at  the 
bottom  of  the  great  longitudinal  fissure.  The  more  important 
structures  upon  the  floor  of  each  can  then  be  studied,  and  the 
position  and  general  direction  of  the  horns  perceived.  The 
middle  and  posterior  horns  can  be  subsequently  laid  open  and 
studied  separately. 


312 


THE  BRAIN. 


The  Third  Ventricle.— In  order  to  expose  this  cavity 
from  above,  the  body  of  the  fornix  must  be  divided  upon  the 
floor  of  the  lateral  ventricles  and  turned  backward.  If  this 
be  done  carefully,  a  vascular  curtain  roof  (the  so-caUed 
''velum  interposltum''\  formed  by  the  pia  mater,  will  be 
exposed.  This  wiU  have  to  be  divided  also,  before  the  cavity 
of  the  ventricle  is  laid  bare. 


Ant.Tulercle, 


peduncle  of 
pineal  dland. 


Jamina  } 
cinerea  ) 


uhinar 
pineal 


Fio.  07. — A  diagram  designed  by  the  author  to  show  the  inner  surface  of  the  optic  thalO' 
mus,  xoilh  the  tubular  gray  matter  removedy  showing  tlie  third  ventricle,  and  the 
arrangement  of  neigJiboring  parts. 

Th.  8up.,  superior  part  of  thalamus;  Th.  inf.,  inferior  part  of  same;  m.  c,  middle  com- 
missure; 1,  section  of  optic  commissure;  2,  infundibulum  and  pituitary  body;  3, 
anterior  commissure  of  third  ventricle;  4,  anterior  crus  of  fornix;  5,  corpus  can- 
dicans  (mimmillary  tubercle) ;  6,  bundle  of  Vicq  d'Azyr  ;  7,  the  third  nerve  ;  8,  crus 
cerebri;  9,  pons  Varolii ;  10,  posterior  commissure;  11,  corpora  quadrigemina ;  12, 
a(iucduct  of  Sylvius;  13,  fourth  ventricle;  14,  third  ventricle.  This  cut  should  be 
compared  with  Fig.  3,  in  which  the  gray  lining  of  the  ventricle  is  intact. 

This  cavity  is  a  narrow  chink  between  the  optic  thalami. 
It  is  bridged  across  by  three  bands,  called  the  anterior,  mid- 
dle, and  posterior  commissures  of  the  ventricle.  The  mid- 
dle or  soft  commissure  is  composed  of  gray  matter,  and 


THE  THIRD  AND  FOURTH   VENTRICLES.  313 

unites  the  thalami.  It  is  often  torn  across  in  removing  the 
brain. 

Posteriorly,  the  third  ventricle  unites  with  the  fourth  by 
means  of  a  narrow  tubular  canal,  the  "  aqueduct  of  Sylvius  " 
(iter  e  tertio  ad  quartum  ventriculum).  This  canal  passes  be- 
neath the  corpora  quadrigemina,  and  may  be  regarded  as  a 
homologue  of  the  central  canal  of  the  spinal  cord,  which  has 
been  expanded  in  the  region  of  the  fourth  ventricle,  in  order 
to  allow  of  the  many  nuclei  of  origin  of  the  cranial  nerves 
found  in  its  floor.  Anteriorly,  the  third  ventricle  communi- 
cates with  the  lateral  ventricle  of  each  hemisphere  by  the 
foramina  of  Monro. 

The  third  ventricle,  the  aqueduct  of  Sylvius,  and  the 
fourth  ventricle  are  lined  with  a  continuation  of  the  gray 
matter  that  surrounds  the  central  canal  of  the  spinal  cord,  the 
so-called  ''  central  tubular  gray  substance?'' 

The  relation  of  the  third  ventricle  to  the  pillars  of  the  for- 
nix, the  lamina  cinerea,  and  the  structures  that  form  the  inter- 
peduncular space  at  the  base  of  the  cerebrum,  are  made  very 
apparent  in  the  preceding  cut. 

The  gray  substance  that  lines  the  third  ventricle  has  been 
described  in  connection  with  the  thalamus,  to  which  the  reader 
is  referred  for  information  respecting  it. 

The  Fourth  Ventricle. — This  cavity  is  properly  regard- 
ed as  an  expansion  of  the  central  canal  of  the  spinal  cord.  It 
communicates  with  the  third  ventricle  above,  and  the  central 
canal  of  the  cord  and  the  subarachnoidean  space  below.  The 
latter  communication  takes  place  through  the  "foramen  of 
Magendie."  It  allows  of  the  entrance  and  escape  of  cerebro- 
spinal fluid.  The  importance  of  this  as  a  means  of  equalizing 
pressure  upon  the  brain  substance  (when  the  vascular  supply 
is  increased  or  diminished)  will  be  considered  in  detail  in  con- 
nection with  the  spinal  meninges. 

The  fourth  ventricle  lies  below  the  level  of  the  cerebral 
hemispheres.  Its  gray  matter  contains  the  nuclei  of  origin  of 
the  more  important  cranial  nerves.  These  have  been  discussed 
in  connection  with  the  architecture  of  the  medulla.     Its  roof 


I 


314  THE  BRAIK 

is  formed  by  the  under  surface  of  the  cerebellum  and  the  so- 
called  "  valve  of  Vieussens." 


THE   COMMISSURES  OF  THE   BRAIK 

In  connection  with  the  ventricles,  the  corpus  callosum  and 
fornix  have  been  mentioned.  They  deserve  further  consider- 
ation, as  they  have  not  been  separately  described  in  previous 
pages. 

The  Corpus  Callosum. — This  commissural  band  has  been 
discussed  to  some  extent  in  those  pages  that  treat  of  the  com- 
missural fibers  of  the  cerebral  hemispheres.  It  is  about  three 
inches  long  by  three  quarters  of  an  inch  in  breadth,  and  lies 
at  the  bottom  of  the  great  longitudinal  fissure.  It  is  the  great 
commissural  band  between  the  hemispheres,  and  forms  the 
roof  of  the  lateral  ventricle  of  each.  Anteriorly,  it  curves 
downward  to  reach  the  base  of  the  brain,  and  posteriorly  it 
dips  downward  to  form  the  *^  sijlenium."  The  anterior  bend 
is  termed  the  *'genu  "or  "  anterior  flexure"  of  the  callosum. 
The  splenium  reaches  as  far  as  the  transverse  fissure  of  the 
cerebrum,  and  bears  intimate  relationship  with  the  pineal 
gland  and  optic  lobes.  The  so-called  ''peduncles  of  the  cal- 
losum • '  reach  to  the  anterior  perforated  spaces  at  the  base  of 
the  cerebrum.  Fibers  of  the  callosum  can  be  traced  to  the 
following  parts  : 

1.  The  white  substance  of  the  cerebral  hemispheres. 

2.  The  gyrus  fornieatus. 

3.  The  fornix. 

4.  The  occipital  lobe. 

5.  The  temporo-sphenoidal  lobe,  along  the  descending 
horn  of  the  lateral  ventricle. 

The  fibers  of  the  callosum  are  both  longitudinal  and  trans- 
verse. They  serve  to  unite  the  component  parts  of  the  cere- 
bral hemispheres.  The  transverse  fibers  probably  assist  in 
uniting  homologous  parts  of  each  hemisphere.  The  function 
of  the  longitudinal  fibers  is  not  well  understood. 

The  corpus  callosum  is  sometimes  defective  or  absent. 


CORPUS  CALLOSUM  AND  FORNIX.  315 

When  so,  the  septum  lucid  am  and  the  fornix  are  also,  as  a 
rule,  defective.  The  mental  condition  of  subjects  with  a  de- 
fective corpus  callosum,  according  to  the  researches  of  Knox, 
is  impaired  in  proportion  to  the  imperfections  found  in  it  and 
the  other  commissural  systems.  Idiocy  and  imbecility  have 
occurred  as  a  consequence  of  this  form  of  congenital  deformity 
of  the  brain.  The  anterior  commissure  appears  to  be  rela- 
tively large  in  those  animals  that  have  the  corpus  callosum 
imperfectly  developed.  It  is  possible  that  this  band  may 
take  the  place  of  the  corpus  callosum  in  those  rare  cases 
where  that  body  is  rudimentary  or  absent  in  man.  Ward 
reports  a  remarkable  observation  ("London  Medical  Gazette," 
March,  1846),  where  the  brain  of  a  child  of  about  one  year  of 
age  separated  into  two  equal  halves  when  it  was  removed 
from  the  skull,  on  account  of  the  absence  of  all  transverse 
commissural  systems  in  the  cerebrum  and  pons. 

The  FoRiN^ix. — The  arched  fibers  of  this  structure  serve  ap- 
parently to  unite  the  tip  of  each  temporo-sphenoidal  lobe  with 
the  thalamus  of  the  corresponding  hemisphere,  and,  by  their 
fusion  in  the  mesial  plane,  to  join  the  two  hemispheres  with 
each  other.  Each  lateral  half  of  the  fornix  presents  an  an- 
terior pillar  (which  passes  to  the  base  of  the  brain  and  then 
doubles  upon  itself  in  order  to  unite  with  the  thalamus  (Fig. 
67),  and  a  posterior  pillar  (which  enters  the  middle  or  descend- 
ing horn  of  the  lateral  ventricle  as  a  flattened  ribbon-like 
band,  called  the  "corpus  fimbriatum").  This  band  termi- 
nates in  the  so-called  "  corpus  dentatum  "  of  the  descending 
horn. 

The  arched  fibers  of  each  lateral  half  of  the  fornix  become 
united  with  those  of  its  fellow  in  the  mesial  line,  thus  forming 
the  so-called  "  body  of  the  fornix." 

The  body  extends,  anteriorly,  from  the  point  of  com- 
mencement of  the  anterior  pillars  of  each  side  to  that  of  the 
posterior  pillars.  It  helps  to  form  the  roof  of  the  third  ven- 
tricle, lying  above  and  in  close  contact  with  the  reflection  of 
the  pia  mater  called  the  "velum  interpositum."  It  becomes 
fused  posteriorly  with  the  corpus  callosum.     The  shape  of 


316  THE  BRAIK 

the  body  of  the  fornix  is  triangular,  the  apex  pointing  for- 
ward.  Its  upper  surface  appears  upon  the  floor  of  the  central 
cavity  of  the  lateral  ventricle.  In  order  to  expose  the  third 
ventricle  of  the  cerebrum  from  above,  it  is  necessary  to  divide 
the  body  of  the  fornix  close  to  the  anterior  pillars,  and  to 
turn  it  backward.  The  velum  interpositum  with  its  vessels 
then  comes  into  view.  This  membrane  has  to  be  also  removed 
before  the  ventricular  cavity  is  seen. 

Commissures  of  the  Third  Ventricle. — The  posterior 
commissure  of  the  third  ventricle  has  been  considered  in  con- 
nection with  the  tegmentum  cruris,  and  the  anterior  corti- 
missure  will  be  discussed  in  connection  with  the  olfactory 
nerves.  The  middle  commissure  is  an  integral  part  of  the 
thalami,  which  it  serves  to  unite. 

THE  membranes  OF  THE  BRAIN. 

The  brain  has  three  coverings,  called,  from  without  in- 
ward, the  dura  mater,  the  arachnoid,  and  the  pia  mater.  The 
exterior,  or  dura,  is  essentially  protective  in  function ;  al- 
though it  serves  some  other  purposes,  such  as  the  formation 
of  venous  channels,  the  support  of  certain  parts,  the  nourish- 
ment of  the  bones,  etc.  The  arachnoid  is  a  fibro-serous  mem- 
brane, and  is  structurally  related  to  the  lymph  channels,  as 
are  all  serous  membranes.  The  pia  is  a  vascular  membrane, 
and  serves  to  nourish  the  parts  with  which  it  comes  in  con- 
tact. It  will  be  necessary  to  consider  each  of  these  mem- 
branes separately. 

The  Dura. — This  is  a  dense  fibrous  membrane,  closely  ad- 
herent to  the  base  of  the  skull  and  along  most  of  the  cranial 
sutures.  It  is  loosely  attached,  however,  to  the  convexity  of 
the  skull,  save  at  the  sutures.  Small  vessels  pass  from  its 
exterior  surface  into  the  diploe,  or  middle  layer  of  the  bony 
skull-cap.  Its  inner  surface  is  smooth,  and  is  lined  with 
pavement  epithelium.  It  is  in  relation  to  the  so-called  ''  sub- 
dural space."  Around  the  margins  of  the  cranial  foramina, 
the  petrosal  ridges,  and  the  crista-galli  process,  the  dura  is 


THE  CEREBRAL  SINUSES.  3I7 

particularly  firm  in  its  attaclmients.  The  ''sella  turcica," 
that  holds  the  pituitary  body,  is  covered  over  by  a  process  of 
this  membrane,  which  binds  the  pituitary  body  firmly  in 
place  and  conceals  it  from  view. 

Processes  of  the  Dura.— The  dura  assists  to  form  three 
processes,  called  the  cerebral  falx,  the  cerebellar  falx,  and 
the  tentorium.  The  falces  of  the  cerebrum  and  cerebellum 
prevent  lateral  oscillation  of  the  cerebral  and  cerebellar 
hemispheres,  while  the  tentorium  supports  the  posterior  part 
of  the  cerebrum  and  prevents  it  from  injuring  the  cerebellum 
by  its  weight. 

The  Cerebral  Sinuses.  —Along  the  upper  and  lower  bor- 
ders of  the  falx  cerebri  the  two  reduplicated  layers  of  the 
dura  assist  to  form  the  superior  and  inferior  longitudinal  si- 
nuses. Where  it  joins  the  tentorium,  the  straight  sinus  is 
formed.  The  attachment  of  the  tentorium  to  the  skull  forms 
the  lateral  sinuses,  by  splitting  of  the  dura  into  two  layers. 

The  occipital  sinuses  run  along  the  sides  of  the  falx  cere- 
belli.  At  the  base  of  the  skull  we  encounter  the  transverse 
and  circular  sinuses,  both  of  which  cross  the  median  line,  and 
also  three  pairs  of  sinuses,  viz.,  the  superior  petrosal,  the  in- 
ferior petrosal,  and  the  cavernous. 

There  are  some  clinical  suggestions  of  value  that  may  be 
made  in  connection  with  the  dura.  Inflammatory  affections 
of  that  membrane  may  induce  thrombosis  of  the  cerebral  si- 
nuses, although  that  condition  can  occur  also  from  extension 
of  inflammation  from  other  parts  by  means  of  the  communi- 
catiDg  veins,  and  as  the  result  of  pressure  exerted  upon  them 
by  intracranial  lesions.  The  vessels  of  the  dura  may  be  the 
seat  of  extravasation  of  blood,  and  suppuration  between  the 
dura  and  the  skull  may  follow  traumatism.  The  nerves  of 
the  dura  cause  a  headache,  when  that  membrane  is  the  seat 
of  disease,  or  is  pressed  upon  ;  as,  for  example,  in  the  case  of 
a  cerebral  tumor.  Encephaloid  cancer  seems  to  occur  most 
frequently  in  the  dura  about  the  foramen  magnum.  In  this 
case,  the  symptoms  would  be  closely  allied  to  those  of  a  le- 
sion of  the  medulla.    The  communication  between  the  cavern- 

23 


318  THE  BR  Am. 

ous  sinus  and  the  facial  veins  by  means  of  the  orbit  explains  ] 
the  liability  of  patients  suffering  from  a  facial  erysipelas  to ' 
a  complicating  meningitis.  Leeching  the  nose  will  relieve! 
headache,  if  congestive  in  type,  because  the  longitudinal  si-  j 
nuses  communicate  with  the  veins  of  the  nose.  Depletion: 
back  of  the  ears  may  also  be  employed  to  deplete  the  lateral  | 
sinus  through  the  mastoid  vein.  The  liability  of  suppuration  \ 
of  the  middle  ear  to  a  complicating  meningitis-  is  well  recog-j 
nized,  and  it  is  to  be  explained  by  the  thinness  of  the  bone  \ 
between  the  dura  and  the  tympanic  cavity.  As  the  sinuses  i 
of  the  brain  receive  tributaries  from  without  chiefly  through . 
the  sutures,  the  operation  of  trephining  should  never  be  per-  • 
formed  over  a  suture  if  it  can  be  avoided.  Scalp- wounds  arej 
especially  liable  to  become  complicated  by  meningeal  symp-  j 
toms  from  the  venous  anastomosis  that  exists  between  the  ex-  j 
terior  and  the  interior  of  the  skull.  The  escape  of  cerebro-  i 
spinal  fluid  from  the  ear,  in  case  of  fracture  of  the  base  of  | 
the  skull,  is  a  valuable  sign  that  the  dura  is  lacerated  in  the  \ 
internal  auditory  canal,  and  the  tympanic  cavity  also  in- ! 
volved.  Displacement  of  the  cerebro-spinal  fluid  from  the! 
subarachnoidean  space  at  the  base  of  the  skull  by  tumors  of  | 
the  dura  or  skull,  the  occurrence  of  meningeal  haemorrhage,  \ 
severe  concussion,  etc.,  may  tend  to  explain  the  occurrence  of  j 
vertigo,  nystagmus,  noises  in  the  ears,  and  some  forms  of  pa-  \ 
ralysis.  This  would  be  particularly  the  case  if  an  excess  of ! 
fluid  were  crowded  into  the  cerebellar  fossa. 

The  Arachnoid. — Between  the  dura  and  the  pia  there ! 
may  be  demonstrated  a  delicate  non- vascular  membrane  of  ■ 
the  fibrous  type,  called  ''the  arachnoid."  It  is  continuous! 
with  the  membrane,  filling  the  same  relative  position  within  I 
the  spinal  canal,  known  as  the  ''spinal  arachnoid."  It  can' 
be  easily  demonstrated  by  means  of  a  blowpipe,  the  injected  i 
air  lifting  it  from  the  pia.  It  forms  sheaths  for  the  cranial  { 
nerves,  embraces  the  basilar  artery,  bridges  over  the  more  im- 1 
portant  sulci  of  the  brain,  covers  the  exposed  portion  of  the ! 
corpus  callosum,  and  forms  the  limiting  membrane  for  the  ] 
lymph-spaces  of  the  more  important  vessels  of  the  cranium.      \ 


TEE  ARACHNOID  AND  PIA  MATER,  3I9 

Between  tlie  arachnoid  and  the  dura  is  a  space,  called 
the  "subdural  space^"^^  and  between  it  and  the  pia  is  another 
space,  known  as  the  "'  suharacJinoidean  space. "^^  The  latter 
is  traversed  by  a  delicate  network  of  fibers,  that  subdivide  it 
into  compartments.  The  subdural  space  is  lined  with  an  en- 
dothelium. Both  spaces  are  filled  with  a  fluid  that  is  similar 
to  that  which  enters  the  ventricles  by  means  of  the  foramen 
of  Magendie.  The  normal  quantity  of  this  fluid  that  is  found 
outside  of  the  brain  varies  from  a  few  drachms  to  about  two 
ounces.  Hilton  compares  this  fluid  at  the  base  of  the  brain 
to  a  water-bed  for  protection  against  transmitted  violence,  as 
when  a  subject  falls  and  strikes  upon  the  feet.  The  effect  of 
any  lesion  that  tends  to  decrease  the  cubical  contents  of  the 
cranial  cavity  must  be  to  displace  this  fluid.  But,  since  the 
fluid  is  not  evenly  distributed  over  the  base  of  the  skull, 
some  regions  are  more  exempt  from  this  displacement  than 
others.  Again,  lesions  of  the  character  described  may  pre- 
vent the  escape  of  the  cerebro- spinal  fluid  through  the  aque- 
duct of  Sylvius,  and  thus  disturb  the  beautifully  adjusted 
relationship  between  the  amount  of  fluid  within  the  ventricles 
and  the  circulatory  apparatus.  Duret  attributes  the  loss  of 
consciousness  that  accompanies  sudden  lesions  of  the  basal 
ganglia  or  the  white  substance  of  the  cerebral  hemispheres  to 
a  rapid  displacement  of  the  cerebro-spinal  fluid.  Blachez 
reports  a  case  where  a  rupture  of  the  basilar  artery  filled  the 
entire  area  of  the  base  of  the  brain  with  blood  (Allen). 

The  Pia. — This  is  a  fibro- vascular  structure  that  lies  in 
direct  contact  with  the  cortex  of  the  brain.  It  is  continuous 
with  the  pia  of  the  spinal  cord,  but  differs  from  it  in  that  it 
is  more  vascular  and  does  not  form  ligaments.  In  the  skull 
it  consists  of  two  layers,  the  outer  being  a  receptacle  of  large 
vascular  trunks  and  the  inner  for  the  smaller  twigs  that  enter 
the  cortex.  The  inner  layer  is  continuous  with  the  neuroglia. 
The  pia  sends  prolongations  into  the  ventricles  of  the  brain, 
chiefly  by  means  of  the  transverse  fissure  that  lies  between 
the  cerebrum  and  the  cerebellum.  Allen  states  that  it  is  so 
closely  adapted  to  the  walls  of  the  fissure  by  which  it  enters 


320  THE  BRAIK 

the  ventricles  as  to  resist  the  pressure  of  the  cerebro-spinal 
fluid,  and  it  thus  prevents  its  escape  from  the  ventricles. 

The  prolongations  of  the  pia  within  the  substance  of  the 
brain  constitute  the  parts  known  as  the  "velum  interposi- 
tum  "  and  the  choroid  plexuses. 

The  velum  interpositum  has  a  triangular  form  and  lies 
immediately  beneath  the  fornix,  and  forms  the  curtain-like 
roof  of  the  third  ventricle.     Its  base  corresponds  to  the  trans- 
verse fissure,  and  its  apex  lies  between  the  foramina  of  Monro. 
It  incloses  the  pineal  gland,  and  overlaps  the  optic  lobes.  ^ 
Two  large  veins  can  be  seen  within  its  substance  that  empty  | 
into  the  straight  vein  of  Galen.    It  is  the  largest  prolongation  ; 
of  the  pia.  ; 

The  superior  choroid  plexuses  are  formed  from  the  lat-  i 
eral  margins  of  ^the  velum  interpositum  and  appear  in  the  j 
lateral  ventricles.  In  each  hemisphere  the  choroid  plexus  of 
the  ventricle  is  prolonged  into  the  middle  or  descending  horn,  ] 
lying  upon  its  floor.  The  vascular  loops  that  compose  this  \ 
plexus  are  covered  with  a  layer  of  pavement  epithelium. 

In  the  third  ventricle,  two  prolongations  from  the  velum  < 
can  be  demonstrated.  These  are  sometimes  prolonged  intoj 
the  fourth  ventricle.  5 

The  inferior  choroid  plexus  lies  upon  the  floor  of  the ; 
fourth  ventricle  (the  posterior  surface  of  the  medulla),  and  I 
consists  of  a  median  tuft  of  vessels  that  envelops  the  under] 
surface  of  the  worm  of  the  cerebellum,  and  two  lateral  pro-  \ 
cesses  that  run  out  into  the  angles  of  the  ventricle.  This  i 
plexus  of  vessels  is  generally  derived  directly  from  the  pia,  ; 
which  penetrates  into  the  fourth  ventricle  through  the  so-  \ 
called  "inferior  transverse  fissure."  This  is  situated  at  thai 
line  of  junction  of  the  under  surface  of  the  cerebellum  and  j 
the  medulla.  In  this  region,  the  arachnoid  membrane  be-  i 
comes  perforated,  forming  the  so-called  "foramen  of  Magen- j 
die,"  through  which  the  cerebro-spinal  fluid  reaches  the  ven-j 
tricular  cavities  of  the  brain.  1 

The  pia  is  supplied  with  nerves  from  the  third,  sixth,  j 
seventh,  eighth,  and  eleventh  cranial  nerves  and  from  thei 


THE   CEREBRAL   CIRGULATIOX.  321 

sympathetic  system.     Its  blood-vessels  are  derived  from  tlie 
vertebral  and  internal  carotid  arteries. 


THE  BLOOD-VESSELS   OF  THE  BEAIN. 

The  vessels  of  the  brain  are  of  great  interest  to  the  sur- 
geon, because  they  have  a  direct  bearing  upon  the  pathology 
and  symptomatology  of  injuries  of  the  head.  To  the  gen- 
eral practitioner  also  the  vessels  of  the  encephalon  furnish 
many  suggestions  of  value  respecting  those  diseases  that 
attack  the  brain  substance  or  the  meninges.  It  is  not  out  of 
place,  therefore,  to  call  attention  to  the  more  important  facts 
that  have  been  published  by  those  observers  who  have  de- 
voted special  care  to  the  investigation  of  the  anatomy  of  the 
vessels  of  the  brain  and  the  peculiarities  of  its  circulation. 

The  blood  is  sent  to  the  brain  and  its  coverings  chiefly  by 
means  of  two  large  trunks  upon  either  side,  the  vertebral  and 
internal  carotid.'  The  vertebrals  enter  th^  skull  by  means  of 
the  foramen  magnum  and  unite  to  form  the  basilar.  The 
carotids  enter  farther  forward,  by  means  of  the  carotid  canals 
in  the  petrous  portion  of  each  temporal  bone.  The  branches 
that  derive  blood  from  the  vertebrals  are  called,  when  col- 
lectively considered,  the  posterior  ov  "vertebral  system,'^'' 
Those  that  spring  from  the  carotids  are  called  the  anterior  or 
"  carotid  sy stem,'''' 

The  '' vertebral  system"  is  distributed  to  the  posterior 
portions  of  the  cerebrum,  the  cerebral  peduncle,  the  cere- 
bellum, pons,  meduUa,  corpora  quadrigemina,  and  the  pos- 
terior part  of  the  thalamus. 

The  '' carotid  system"  is  distributed  to  all  the  important 
parts  of  the  cerebrum  lying  anterior  to  the  cerebral  peduncle 
in  the  region  of  its  base,  the  frontal  lobes,  the  anterior  and 
outer  parts  of  the  temporo-sphenoidal  lobes,  the  insula,  the 
two  nuclei  of  the  corpus  striatum,  and  the  anterior  portion  of 
the  thalamus. 

^  The  coverinc^s  of  the  brain  derive  blood  from  other  sources  as  well ;  chiefly  from 
the  internal  maxillary,  ascending  pharyngeal,  and  occipital  arteries. 


322  THE  BRAIN. 

It  will  be  necessary  to  consider  the  separate  branches  of 
the  internal  carotid,  vertebral,  and  basilar  arteries,  in  order 
to  give  the  reader  a  clear  conception  of  the  areas  of  brain- 
tissue  that  are  nourished  by  each. 

The  INTERNAL  CAROTID  ARTERY,  ou  escaping  froui  its 
bony  canal  and  entering  the  cavity  of  the  skull,  turns  sharply 
upward  and  backward  and  gives  off  the  following  branches : 
1,  the  ophthalmic ;  2,  the  anterior  choroid  ;  3,  the  anterior 
cerebral ;  4,  the  middle  cerebral ;  and,  5,  the  posterior  com- 
municating. 

The  ophtlialmic  artery  passes  directly  into  the  orbit  and 
distributes  its  blood  by  many  branches  to  the  eye  and  its 
appendages.  This  fact  enables  the  neurologist  to  determine 
often,  by  means  of  the  ophthalmoscope,  the  condition  of  the 
cerebral  vessels,  because  similar  changes  may  be  detected  in 
the  blood-vessels  of  the  retina. 

The  anterior  choroid  artery  passes  backward  to  the  trans- 
verse fissure  of  the  brain  and  assists  in  supplying  the  ves- 
sels of  the  choroid  plexus.  It  lies  in  relation  with  the  ex- 
tremity of  the  temporo- sphenoidal  lobe,  which  conceals  it 
from  view  for  a  part  of  its  course. 

The  anterior  cerebral  artery  winds  around  the  edge  of  the 
optic  chiasm  and  meets  its  fellow  about  one  twelfth  of  an 
inch  in  front  of  the  chiasm,  where  the  two  become  joined 
by  a  short  branch,  the  anterior  communicating  artery.  From 
this  point  the  two  vessels  run  side  by  side,  following  the 
curve  of  the  corpus  callosum  from  its  beak  to  its  posterior 
extremity.  This  vessel  supplies  the  optic  chiasm,  the  lamina 
cinerea,  the  anterior  portion  of  the  caudate  nucleus,  the 
corpus  callosum  and  the  adjacent  fornix,  and  the  convolu- 
tions upon  the  inner  surface  of  the  hemisphere  of  the  same 
side,  as  far  as  the  cuneus.  The  importance  of  the  relation  of 
this  vessel  to  the  edge  of  the  optic  chiasm,  as  a  factor  in  the 
production  of  that  rare  condition  known  as  *'bi-temporal 
hemianopsia"  has  been  shown  in  a  paper  by  Prof.  H. 
Knapp,  of  this  city.  This  condition  is  discussed  later  in 
the  volume. 


THE  CEREBRAL   CIRCULATION.  323 

The  middle  cerebral  artery  is  especially  important,  be- 
cause it  is  now  known  to  supply  the  so-called  ''  motor  area" 
of  the  cerebral  cortex.  On  leaving  the  internal  carotid  trunk, 
it  crosses  the  anterior  perforated  space  and  enters  the  Syl- 
vian fissure.  Here  it  gives  off  its  main  branches,  which  are 
usually  four  in  number.  All  along  its  upper  surface,  how- 
ever, small  arterial  twigs  are  given  off  in  the  Sylvian  fissure 
and  in  the  neighborhood  of  the  anterior  perforated  space. 
These  enter  the  substance  of  the  brain  and  supply  the  cau- 
date and  lenticular  nuclei  of  the  corpus  striatum  and  the 
internal  and  external  capsule.  Its  main  branches  take  dif- 
ferent directions.  One  runs  forward  into  the  convolutions  of 
the  frontal  lobe,  one  backward  as  far  as  the  extremity  of  the 
horizontal  limb  of  the  Sylvian  fissure,  and  two  pass  upward 
on  either  side  of  Rolando's  fissure  as  far  as  the  upper  frontal 
and  parietal  gyri,  that  lie  adjacent  to  the  great  longitudinal 
fissure.  Thus  it  appears  that  the  basal  ganglion  which  are 
connected  with  motion  derive  their  blood-supply  from  this  ves- 
sel, as  do  also  the  island  of  Reil  (the  insula)  and  the  convolu- 
tions that  bound  the  fissure  of  Rolando  and  the  Sylvian 
fissure.  Embolism  or  thrombosis  of  the  main  trunk  causes  a 
hemiplegia  of  the  opposite  side  of  the  body  and  motor 
aphasia,  because  the  motor  gyri  and  Broca's  center  of  articu- 
late speech  are  deprived  of  blood.  Should  some  one  of  its 
branches  alone  be  occluded  and  the  main  trunk  escape,  these 
symptoms  would  be  modified.  The  middle  cerebral  artery  of 
the  left  side  is  the  most  common  seat  of  embolism,  because 
^that  artery  is  the  terminal  branch  of  a  direct  line  of  vessels 
arising  from  the  arch  of  the  aorta  in  such  a  way  as  to  favor 
the  entrance  of  floating  particles  in  the  blood  into  the  mouth 
of  the  left  common  carotid  artery. 

The  posterior  communicating  artery  connects  the  internal 
carotid  with  the  posterior  cerebral,  and  thus  establishes  the 
vascular  circle  at  the  base  of  the  brain  known  as  the  '*  circle 
of  Willis."  It  gives  off  branches  that  supply  the  tuber 
cinereum,  the  corpora  mamillaria,  the  optic  tracts,  and  the 
inner  surface  of  the  thalamus  (Westbrook). 


324  TEE  BRAIK 

The  VERTEBRAL  ARTERIES  of  either  side  unite  to  form  the 
basilar.  This  vessel  gives  off  the  posterior  cerebral  vessels, 
at  its  anterior  extremity,  and  thus  assists  to  form  the  circle 
of  Willis.  Along  its  sides,  transverse  branches  are  given 
off.  One  of  these,  the  auditory  artery,  supplies  the  ear 
mechanism. 

The  posterior  cerebral  artery  arises  from  the  anterior  ex- 
tremity of  the  basilar  and  passes  outward  and  backward 
around  the  crus  cerebri  to  reach  the  temporal  and  occipital 
lobes  of  the  cerebrum.  It  follows  the  course  of  the  calcarine 
fissure  (Westbrook).  As  it  crosses  the  posterior  perforated 
space,  small  arterial  twigs  escape  and  enter  the  substance  of 
the  brain  to  supply  the  thalamus.  A  posterior  choroid 
branch  is  sometimes  given  off.  This  assists  to  form  the  velum 
interpositum  and  the  choroid  plexus,  and  gives  off  branches 
to  the  pineal  gland  and  optic  lobes.  The  main  trunk  of  the 
posterior  cerebral  artery  supplies  the  crus  cerebri,  optic  lobes, 
and  geniculate  bodies. 

The  basal  ganglia  of  the  cerebrum  derive  their  vascular 
supply  from  twigs  that  arise  from  the  vessels  composing  the 
circle  of  Willis.  Buret  has  observed  the  circular  outline  of 
these  ganglionic  twigs.  In  a  diagram  designed  by  West- 
brook,'  the  basal  ganglia  have  been  projected,  as  it  were, 
upon  the  surface  of  the  cerebrum.  The  outer  limit  of  these 
ganglionic  masses  constitutes  almost  a  perfect  circle.  To 
quote  the  author  of  the  cut,  *'The  diagram  was  obtained  by 
making  a  horizontal  section  of  a  cerebrum,  low  enough  to  cut 
the  lenticular  nucleus,  and  then  perforating  the  brain  with 
styles  so  as  to  mark  out  the  limits  of  the  ganglia. 

As  regards  the  distribution  of  arteries  within  the  brain 
substance,  some  practical  discoveries  have  been  made.  Buret 
found  that  injections  of  individual  trunks  distributed  to  the 
cerebral  cortex  passed  over  to  a  slight  extent  into  areas  sup- 
plied by  other  vessels.  He  drew  the  conclusion  from  this 
fact  that  a  collateral  circulation  did  exist  between  vessels  of 
large  size,  not  only  at  the  base  of  the  brain  but  also  upon  the 

*  "  Annals  of  Anatomy  and  Surgery,"  vol.  ii. 


TEE  CEREBRAL    CIRCULATION:  325 

surface  of  the  cerebral  hemisplieres.  The  vessels  that  run 
over  the  surface  of  the  hemispheres  in  the  meshes  of  the  pia 
give  off  arterial  twigs  that  everywhere  dip  into  the  cortex 
and  penetrate  its  layers.  These  are  subsequently  prolonged 
into  the  medullary  substance  of  the  hemispheres.  It  seems 
probable  that  the  nutrient  vessels  of  the  cortex  do  not  anasto- 
mose with  each  other  or  with  those  that  enter  the  brain  sub- 
stance from  the  region  of  its  base.  Westbrook  claims,  as  a 
result  of  special  researches,  that  a  portion  of  the  centrum 
ovale  of  the  hemispheres  is  destitute  of  vessels. 

The  vessels  of  the  ventricles  are  derived  from  the  choroid 
plexuses  and  the  velum  interpositum.  Some  twigs  are  given 
off  from  the  latter  of  these  sources  to  the  thalami  and  the 
commissures  of  the  third  ventricle,  and  also  to  the  caudate- 
nuclei  of  the  corpora  striata.  According  to  Buret,  these 
sometimes  anastomose  with  the  branches  of  the  middle  cere- 
brals given  off  in  the  Sylvian  fissures. 

The  choroid  plexuses  do  not  appear  to  nourish  the  brain 
substance  or  its  ganglia,  but  are  destined  rather  to  assist  in 
the  secretion  of  the  ventricular  fluid.  They  derive  blood 
from  the  anterior  and  posterior  choroid  vessels. 


THE  CRANIAL  NERVES. 

THEIR  ANATOMY,  PHYSIOLOGY,  AND  CLINICAL  VALUE. 


THE  CRANIAL  NEEVES. 


In  the  previous  chapter  many  points  pertaining  to  the 
superficial  and  deep  attachments  of  the  cranial  nerves  have 
been  incidentally  mentioned  whenever  different  regions  of  the 
brain  from  which  they  arise  have  been  considered.  The  nu- 
clei of  origin  of  some  of  the  nerves  have  been  discussed  in 
detail.  It  seems  to  me  advisable,  however,  to  call  attention 
again  to  some  scattered  hints,  which  have  been  dropped  re- 
specting these  nerves,  before  they  are  individually  considered 
from  a  jDhysiological  and  clinical  standpoint. 

The  nerves  which  arise  from  the  brain  are  arranged  as 
twelve  pairs  (according  to  Soemmering),  which,  from  before 
backward,  are  called  the  olfactory,  optic,  motor-oculi,  troch- 
learis,  trigeminus,  abducens,  facial,  auditory,  glosso-pharyn- 
geal,  pneumogastric,  spinal  accessory,  and  hypoglossal.  All 
of  these,  excepting  the  ninth,  tenth,  and  eleventh  pairs,  are 
confined  in  their  distribution  to  the  head;  while  the  other 
three  have  a  distribution  to  the  structures  of  the  neck  and 
trunk. 

Willis  has  divided  the  cranial  nerves  into  nine  pairs, 
grouping  the  seventh  and  eighth  nerves  as  one  pair,  and  the 
ninth,  tenth,  and  eleventh  as  one  pair. 

The  OLFACTOEY  TEACT  AND  BULB  must  be  regarded  in  the 
light  of  a  constituent  part  of  the  brain  rather  than  as  a  true 
nerve.  This  is  demonstrated  by  its  method  of  development, 
as  well  as  by  certain  peculiarities  in  its  structure.  During 
foetal  life  the  olfactory  lobe  or  tract  consists  of  a  diverticu- 


330 


THE  CRANIAL  NERVES. 


lum  from  the  hollow  globe  of  the  cerebral  hemisphere,  and  its 
cavity  then  communicates  with  the  lateral  ventricle.  Its  cor- 
tical layer  is  continuous  superiorly  Avith  that  of  the  rest  of 
the  brain. 

The  olfactory  bulb  forms  a  cap  which  embraces  the  pro- 
longation of  the  brain  substance.  In  its  interior,  rounded 
masses — the  so-called  ''glomeruli"  of  the  stratum  glomerulo- 
sum—SLie  found.     These  are  peculiar  to  this  region. 


Fig.  68. — The  base  of  the  skull  and  the  cranial  nerves. 

The  nerves  are  indicated  by  Roman  numerals:  1,  attachment  of  the  tentorium;  2,  sella 
turcica ;  3,  carotid  artery. 


Each  olfactory  nerve  fiber  appears  to  be  wound  into  a 
knot,  as  it  were,  by  the  aid  of  nerve  cells  that  are  inserted  in 
its  course.  The  cortical  substance  of  the  olfactory  tract  or 
lobe  presents,  moreover,  peculiarities  in  respect  to  the  cells 
which  compose  it.  These  are  in  marked  contrast  to  those 
which  compose  the  cerebral  cortex. 


DEEP   ORIGm  OF  OLFACTORY  FIBERS.  331 

The  olfactory  nerve  has  three  peduncles  or  roots  by  means 
of  which  its  fibers  find  their  deep  origins  within  the  brain 
substance.  The  external  or  long  root  passes  along  the  front 
border  of  the  anterior  perforated  space,  and  enters  the  tem- 
poro- sphenoidal  lobe.  The  middle  or  gray  root  arises  from 
the  cortical  gray  matter  covering  the  anterior  perforated 
space.  The  internal  root  passes  into  the  substance  of  the 
frontal  lobe. 

The  view  is  held,  from  some  results  obtained  by  Gud- 
den's  method,  that  the  olfactory  sense  is  presided  over  by 
a  center  or  nucleus  wMch  is  situated  in  the  substance  of 
the  temp  or  0- sphenoidal  lohe^  and  that  decussating  fibers  can 
be  proven  to  pass  between  the  olfactory  tracts  and  also  be- 
tween the  centers  of  smell  of  each  hemisphere.  The  diagram 
introduced  (Fig.  69)  will  help  to  illustrate  in  a  rough  way  the 
conclusions  advanced  by  late  observers. 

When  the  optic  thalamus  was  under  consideration,  the 
opinion  of  Luys,  that  a  center  of  smell  could  also  be  demon- 
strated within  the  substance  of  that  ganglion,  was  commented 
upon.  Some  pathological  facts,  as  well  as  clinical  experi- 
mentation (to  which  that  author  refers),  appear  to  lend  cre- 
dence to  the  view  that  the  optic  thalamus  is  associated,  to  a 
greater  or  less  extent,  with  the  special  senses  of  smell,  sight, 
and  hearing.  Its  anatomical  connections  with  this  special 
sense  are,  however,  a  subject  of  pure  conjecture  as  yet.  Gud- 
den's  method  of  research  does  not  sustain  the  opinion  of 
Luys. 

The  late  investigations  of  Flechsig  have  led  him  to  the 
conclusion  that  the  olfactory  tracts  can  be  traced  backward  as 
three  bundles.  One  of  these  passes  to  the  base  of  the  frontal 
lobe,  and  probably  terminates  in  the  gyrus  fornicatus;  one 
goes  to  the  cortex  of  the  gyrus  uncinatus;  and  one  can  be 
traced  to  the  internal  capsule  of  the  cerebrum,  by  means  of 
the  anterior  perforated  lamina.  Ganser  and  Gudden  (by 
means  of  the  latter's  method  of  observing  the  atrophic  changes 
that  follow  the  extirpation  of  certain  parts  in  the  newly-born 
rabbit)  seem  to  have  arrived  at  the  conclusion  that  the  "olfac- 


332 


TEE  CRANIAL  NERVES. 


tory  portion  "  of  the  anterior  commissure  of  the  brain  connects 
the  two  bulbs  of  the  olfactory  nerves,  and  the  so-called  ''tem- 
poral portion "  of  the  anterior  commissure  connects  the  tem- 
poral lobes  of  the  two  hemispheres. 


Olfaetor"^ 
nerves 


Olfactory 
Centre 

FiQ.  69. — A  diagram  designed  by  the  author  to  illustrate  the  p'obable  decussation  of  the 
fibers  of  the  olfactory  tracts. 

0.  B.,  olfactory  bulbs;  0.  T.,  olfactory  tracts;  1,  2,  3,  internal,  middle,  and  external 
roots  of  same ;  C.  S.,  corpus  striatum  of  each  hemisphere  of  the  cerebrum ;  a,  fibers 
connecting  the  olfactory  tracts ;  6,  fibers  connecting  the  centers  of  smell ;  a-6,  ante- 
rior commissure,  with  its  two  sets  of  fibers. 


The  fact  that  the  so-called  anterior  commissure  of  the 
brain  consists  of  two  strands  (the  temporal  and  olfactory 
fasciculi  of  Ganser)  is  not  new.  It  is  only  the  verification  of 
the  view  that  the  olfactory  apparatus  can  be  proven  to  have 
an  anatomical  relationship  with  the  anterior  commissure  that 
deserves  special  notice.  In  man  and  the  monkey  tribe,  the 
temporal  fasciculus  is  much  larger  than  the  olfactory.  In  the 
lower  mammals  (particularly  in  the  rabbit,  hedgehog,  and 
mole),  the  olfactory  strand  seems  to  be  developed  in  excess  of 
the  temporal. 

The  fibers  of  the  optic  nerve  have  been  already  consid- 
ered at   some  length  when  the  corpora  quadrigemina  were 


DEEP   ORIGIN   OF  OPTIG  FIBERS. 


333 


under  discussion.  The  reader  is  referred,  therefore,  to  pre- 
vious pages  for  information,  which  it  is  unnecessary  to  repeat 
here.  The  admirable  diagrams  designed  by  Munk  to  illus- 
trate his  views  respecting  the  areas  of  vision  within  the  cortex 
of  the  occipital  lobes  will  possibly  prove  of  value,  in  connec- 
tion with  others  which  have  been  designed  by  the  author  to 
show  the  general  relations  of  the  optic  fibers  to  different  parts 
of  the  brain  (Figs.  42,  43,  44,  and  73). 


Figs.  70  and  71. — The  visual  tracts.     (Munk.) 

A,  visual  area  of  right  occipital  lobe  (dotted) ;  a,  same  of  left  side  (lined) ;  R,  r,  retinae 
(right  and  left) ;  B,  areas  of  hearing,  contiguous  to  the  visual  areas ;  Ch,  optic 
chiasm.     This  figure  may  be  contrasted  with  Fig.  43. 


The  optic  nerves  will  be  separately  described  in  subse- 
quent pages,  and  many  points  of  clinical  interest  will  be 
mentioned  in  connection  with  them.  The  deep  origin  of 
the  optic  fibers  is  as  yet  a  matter  of  dispute  among  authors 
of  note. 

24 


334  THE  CRANIAL  NERVES. 

The  superior  corpora  quadrigemina,  the  pulvinar  of  each 
optic  thalamus,  and  the  external  geniculate  bodies  are  un- 
questionably parts  of  the  optic  apparatus.  The  fillet  is  prob- 
ably connected  also  to  some  extent  with  the  visual  function. 
Certain  convolutions  of  the  cerebral  cortex  (probably  those  of 
the  occipital  lobes)  are  concerned,  moreover,  in  the  conscious 
perception  of  retinal  impressions  (see  page  180).  The  cere- 
bellum is  supposed  also  to  receive  afferent  fibers  from  the 
organ  of  sight. 

Munk  believes  that  in  the  dog  three  distinct  visual  areas 
in  the  retina  correspond  to  three  ''visual  spheres"  in  the  cor- 
tex of  the  occipital  lobe  of  the  brain.  The  external  part  of 
each  retina  is  connected  with  the  external  part  of  the  cortical 
visual  area  of  the  corresponding  cerebral  hemisphere ;  while 
the  central  and  internal  portions  are  connected  with  corre- 
sponding parts  of  the  cortical  visual  area  of  the  opposite  cere- 
bral hemisphere. 

In  connection  with  experiments,  made  to  determine  the 
arrangement  of  the  optic  nerve  fibers  in  the  chiasm  as  well  as 
their  relation  to  the  various  ganglia  of  the  brain,  Gudden 
claims  to  have  demonstrated  that  a  band  of  fibers  exists  with- 
in the  optic  tract  and  closely  intermingled  with  its  fibers  that 
do  not  degenerate  when  the  eyeballs  of  a  young  rabbit  are 
extirpated.  He  applies  the  term  "  inferior  cerebral  com- 
missure "  to  this  band,  and  believes  that  it  serves  as  a  direct 
commissure  between  the  optic  thalami.  He  found  that  it 
remained  unchanged  even  after  the  optic  lobes  and  the  ge- 
niculate bodies  were  destroyed ;  hence  he  concludes  that  it 
is  in  no  wise  associated  with  the  visual  sense. 

Respecting  the  question  of  decussation  of  the  optic 
fibers,  the  same  observer  has  arrived  at  the  following  con- 
clusions : 

1.  That  a  complete  decussation  takes  place  in  the  chiasm 
of  the  bird  species. 

2.  That  the  decussation  is  only  partial  in  the  higher  mam- 
malia, although  the  proportion  of  the  decussating  fibers  to 
the  non-decussating  is  subject  to  variations. 


ARRANGEMENT  OF  OPTIC  FIBERS.  335 

3.  The  direct  bundle  does  not  occapy  the  same  relative 
position  in  the  optic  tract  in  all  mammalia. 

4.  That  semi-decussation  exists  in  all  animals  possessing 
binocular  vision.  Total  decussation  accompanies  monocular 
vision  only. 

5.  That  there  does  not  exist  any  "inter-retinal  bundle," 
as  claimed  by  some  observers. 

6.  That  three  sets  of  fibers  exist  in  the  optic  system  of 
mammals :  (a)  The  optic  libers,  which  are  both  crossed  and 
direct ;  {h)  the  fibers  of  the  inferior  cerebral  commissure  ;  (c) 
certain  "hemispheric  fibers,"  whose  course  and  terminations 
are  not,  as  yet,  definitely  determined. 


-The  normal  visual  field. 

The  field  is  marked  off  in  degrees,  so  that  a  drawing  of  the  visual  field  of  any  individual 
patient  by  means  of  a  perimeter  may  be  compared,  when  deemed  abnormal. 

Ganser  has  lately  published  a  confirmation  of  Gudden's 
experiments  and  conclusions  drawn  from  the  rabbit,  by  a 
similar  set  of  experiments  made  upon  cats.  His  deductions 
in  reference  to  the  cortical  and  retinal  distribution  of  the 
optic  fibers  seem  to  coincide  with  the  physiological  deduc- 
tions of  Munk.  Both  Ganser  and  Gudden  seem  to  agree  that 
no  connection  can  be  proven  to  exist  between  the  inferior 
corpora  quadrigemina  or  the  internal  corpora  geniculata  and 
the  optic  apparatus. 


THE  CRANIAL  NERVES. 

Flechsig  has  lately  published  the  results  of  researches 
made  by  him  in  reference  to  the  optic  fibers  by  the  degenera- 
tive method.  He  excludes  (as  do  Gudden  and  Ganser)  the 
corpus  geniculatum  internum  and  the  posterior  corpus  quad- 
rigeminum  from  the  optic  apparatus.  He  claims  that  some 
of  the  optic  fibers  turn  backward  upon  their  own  course  to 
reach  the  radiating  fibers  of  the  external  geniculate  body  and 
reach  the  visual  area  of  the  cerebral  cortex  by  passing  to  the 
outer  side  of  the  posterior  cornu  of  the  lateral  ventricle.  He 
places  the  cortical  area  of  vision  in  the  cuneus  and  the 
occipital  lobe. 

A  band  of  fibers  that  crosses  in  the  substance  of  the  crus 
cerebri  has  been  called  by  Gudden  the  ''transverse  pedun- 
cular tracts  It  extends  to  the  optic  lobe  of  either  side, 
and  then  disappears.  It  seems  probable  that  it  is  function- 
ally, as  well  as  anatomically,  related  to  the  apparatus  of 
vision,  because  the  later  investigations  of  Gudden  tend 
to  demonstrate  that  its  fibers  have  a  direct  connection  with 
the  visual  area  of  the  cortex  and  the  primary  centers  of 
vision.  Wilder,  in  his  work  on  "Anatomical  Technology," 
has  suggested  the  term  "  cimhia "  for  this  tract,  although 
he  does  not  appear  to  recognize  its  association  with  the 
visual  mechanism. 

Wernicke  has  demonstrated  that  a  tract  of  fibers  passes 
from  the  pulvinar  (a  part  of  the  optic  thalamus)  to  the  cor- 
tex of  the  occipital  lobe,  and  that  this  tract  is  a  direct 
continuation  of  the  fibers  of  the  optic  tract.  It  reaches 
the  occipital  lobe  by  passing  beneath  the  "angular  gyrus." 
Ferrier's  and  Dalton's  experiments  upon  that  convolution 
probably  affected  vision  by  causing  injury  to  the  tract  of 
Wernicke. 

The  MOTOR-ocuLi  and  trochlear  nerves  have  their  deep 
origin  apparently  from  a  gray  nucleus  (which,  according  to 
some  authors,  is  common  to  both  nerves)  within  the  gray 
matter  surrounding  the  aqueduct  of  Sylvius.  This  nucleus  is 
in  direct  communication  with  both  the  corpora  quadrigemina 
and  the  lenticular  nucleus  of  the  corpus  striatum.     The  nu- 


ORIGIN  OF  THIRD  AND  FOURTH  NERVES.  337 


cleus  of  the  fourth  nerve  seems  to  be  composed  of  larger 
cells  than  that  of  the  third  nerve,  however,  and  to  occupy  the 
level  defined  by  the  line 
of  separation  bet'^een  the 
anterior  and  posterior  cor- 
pora quadrigemina. 

Some  authors  describe 
an  additional  nucleus  for 

the  TROCHLEAR  NERVE  in 

the  locus  coeruleus.  It 
is  apparently  proven  that 
the  fibers  of  the  fourth 
nerve  decussate  with  those 
of  its  fellow  after  passing 
backward  from  its  nucle- 
us and  piercing  the  root 
of  the  aqueduct  of  Syl- 
vius. They  then  traverse 
the  crus  cerebri  and  es- 
cape at  its  superior  and 
external  border. 

The  nucleus  of  origin 
(Fig.  45)  of  the  third  cra- 
nial nerve  of  each  side 
seems  to  be  capable  of 
subdivision  into  groups  of 
cells  which  preside  over 
movements  of  special  mus- 
cles of  the  orbit. 

Thus  we  may  clinical- 
ly recognize  the  existence 
of  a  special  nucleus  for 
visual  "  accommodation  " ; 
for  pupillary  movements ; 
and  for  the  internal  rectus,  the  superior  rectus,  the  levator 
palpebrse,  the  inferior  rectus,  the  inferior  oblique,  and  the 
superior  oblique  muscles. 


Fig.  73. — Horizontal  section  of  a  monkey's 
brain.     (Wernicke.) 

n.  c,  nucleus  caudatus ;  n.  /.,  nucleus  lenticula- 
ris ;  c.  <z.,  anterior  commissure ;  c.  L.,  body 
of  Luys ;  c.  e.,  external  capsule ;  c.  g.  e.,  ex- 
ternal geniculate  body;  c.l.,  claustrum;  i, 
Island  of  Kiel ;  p.  c,  posterior  cornu ;  c.  p., 
posterior  commissure ;  q.  a.,  corpora  quad- 
rigemina anterior;  /.  c,  calcarine  fissure; 
m,  optic  fibers  to  occipital  lobe. 


338 


THE  CRANIAL  NERVES. 


This  fact  probably  explains  how  the  existence  of  ''ex- 
ternal ophthalmoplegia  "  and  other  distinct  forms  of  orbital 

paralysis   may  occur 

C"'  <J'  from   organic   lesions 

..'-'     X  in  the  region  of  the 

tegmentum. 

>  .  The       TRIGEMINAL 

NERVE  resembles  the 
spinal  nerves  in  pos- 
sessing both  a  mo- 
tor and  sensory  root. 
The  analogy  is  height- 
ened, moreover,  by 
the  development  of 
the  ganglion  of  Gas- 
ser  upon  the  sensory 
root.  The  deep  fibers 
of  this  nerve  demand 
detailed     descrip- 


4"'N. 


a 


Fig.  74. — A  diagram  designed  hy  tlie  author  to  illustrate 
the  origin  and  course  of  the  fourth  cranial  nerve. 

The  section  is  on  a  level  with  the  line  of  division 
between  the  anterior  and  posterior  quadrigeminal 
bodies.  IV.  n.,  nucleus  of  the  trochlear  nerve ; 
4th  N.,  fibers  of  the  trochlear  nerve;  S.,  aque- 
duct of  Sylvius ;  C.  ^.,  corpora  quadrigemina. 
Note  the  decussation  of  the  fibers  in  the  gray 
matter  which  surrounds  the  aqueduct  of  Sylvius. 

tion,     because     they 
take  their  origin  from  several  nuclei  (shown  in  Fig.  55). 

1.  Some  fibers  join  the  trigeminal  nuclei  of  the  medulla. 
The  sensory  nucleus  is  situated  as  high  as  the  level  of  the 
point  of  escape  of  the  nerve  from  the  pons  Varolii  and  is 
analogous,  in  the  opinion  of  some  authors  of  note,  to  the 
posterior  horn  of  the  gray  matter  of  the  spinal  cord.  It  ex- 
tends along  the  outer  part  of  the  floor  of  the  fourth  ventricle. 

2.  The  so-called  '' ascending  root  of  the  nerw^^  is  associ- 
ated with  the  posterior  columns  of  the  spinal  cord  as  low  as 
the  middle  of  the  cervical  region.  Its  fibers  are  found  to  pass 
through  these  columns  from  their  origin  in  the  posterior 
horns  to  reach  the  tubercle  of  Rolando  in  the  medulla.  The 
fibers  of  the  ascending  root  of  the  trigeminus  are  associated 
with  the  sensory  portion  of  that  nerve. 

3.  The  fibers  of  the  so-called  "  descending  root  of  the 
nerve'^^  apparently  arise  (1)  from  the  cerebellum  ;  (2)  from  the 
locus  coeruleus  ;  (3)  from  a  collection  of  cells  in  the  lateral 


BEEP   ORIGIN   OF  FACIAL  FIBERS. 


339 


wall  of  the  aqueduct  of  Sylvius ;  and  (4)  from  a  large-celled 
motor  root,  in  the  region  of  the  corpora  quadrigemina.  The 
descending  root  of  the  trigeminus  is  associated  chiefly,  if  not 
exclusively,  with  the  motor  fibers  of  the  nerve. 

The  ABDUCEJS^s  NERVE  arises  from  a  nucleus  within  the 
medulla  composed  of  large  cells  and  situated  near  to  the  junc- 
tion of  the  medulla  and  pons  at  the  bottom  of  a  groove  in  the 
floor  of  the  fourth  ventricle.  A  communication  probably  ex- 
ists between  this  nucleus  and  that  of  the  motor- oculi  nerve  of 
the  opposite  side. 

The  FACIAL  NERVE  arises  from  a  nucleus  which  appears  to 
be  a  continuation  of  that  of  the  abducens,  but  lying  deeper 
in  the  substance  of  the  medulla,  and  also  from  a  nucleus  {in- 
ferior facial  nucleus)  in  the  substance  of  the  pons.     Some 

flbers  of  the  nerve  de- 
.^-=-^   ^^^-^  scend  in  the  crus  cere- 

\^^^^ ^^^:\  I  /^\\  ^^1  >  probably  from  the 

\V^X:__._^N^\\\\I/  „,.  \\^  lenticular    nucleus    of 

the  corpus  striatum  of 
the  opposite  cerebral 
hemisphere.  The  pe- 
culiar course  of  the 
facial  fibers  in  the  me- 
dulla is  shown  in  Fig. 
65.  Gowers  denies  the 
statement,  which  was 
once  accepted,  that  the 
facial  nerve  arises  in 
part  from  the  nucleus 
of  the  abducens  nerve. 
The  fibers  of  the  facial 
nerve  form  a  distinct 
loop^  by  doubling  upon 
themselves,  before  es- 
caping from  the  me- 
dulla. The  relation  of  facial  paralysis  to  lesions  of  the  pons 
has  been  discussed  on  page  291. 


^ina.ii 


a.hi.f 

Fig.  75. — Section  of  the  medulla  at  its  upper  part. 

a.  m.f.,  anterior  median  fissure;  p.m./.,  posterior 
median  fissure ;  0,  olivary  body ;  s.  g.^  sub- 
stantia gelatinosa;  /.  r.,  reticular  fonnation; 
P,  anterior  pyramid;  Va,  ascending  root  of 
fifth  nerve;  h  and  a,  two  bundles  of  audi- 
tory nerve  inclosing  r.  6.,  the  restiform  body ; 
VIII  a.  n.j  VIII  p.  n.,  anterior  and  posterior  nu- 
clei of  the  auditory  nerve;  n.f.t.j  nucleus  of 
the  funiculus  tereles;  XII  N.,  nucleus  of  the 
hypoglossal  nerve. 


840  THE  CRANIAL  NERVES. 

The  AUDITORY  NERVE  arises  from  four  nuclei  within  the 
substance  of  the  medulla. 

A  small  fasciculus  escapes  from  the  medulla  between  the 
facial  and  auditory  nerves,  called  the  '' portlo  intermedia  of 
Wrishergy  This  is  now  considered  as  in  no  way  related  to 
the  sense  of  hearing,  but  rather  to  that  of  taste.  Although  it 
passes,  along  with  the  auditory  nerve,  into  the  internal  audi- 
tory canal,  it  subsequently  joins  the  facial  nerve  and  prob- 
ably helps  to  form  the  chorda- tympani  branch  of  that  nerve. 

The  nuclei  of  the  auditory  nerve  lie  on  a  level  with  the 
broadest  part  of  the  fourth  ventricle.  They  are  termed  the 
*' anterior  median,"  the  "posterior  median,"  the  "anterior 
lateral,"  and  the  ' '  posterior  lateral."  They  have  been  already 
described  in  connection  with  the  medulla.  Some  fibers  of  the 
auditory  nerve  have  been  traced  to  the  superior  vermiform 
process  of  the  cerebellum  (page  232). 

Figs.  66  and  75  will  show  the  relative  situation  of  the  four 
acoustic  nuclei  within  the  medulla.  Some  of  the  fibers  of  the 
auditory  nerve  decussate. 

The  NINTH  or  glosso-pharyngeal  nerve  arises  from  a 
nucleus  within  the  substance  of  the  medulla  that  is  not  sepa- 
rated by  a  distinct  boundary  from  that  of  the  pneumogastric. 
Its  situation  and  extent  are  shown  in  the  "drawing  of  Erb 
(Fig.  65). 

The  TENTH  or  pneumogastric  nerve  arises  from  a  nucleus 
within  the  medulla  situated  in  its  lower  half  in  the  floor  of 
the  fourth  ventricle,  and  also  from  a  nucleus  in  the  vicinity 
of  the  olivary  body.  The  latter  is  not  shown  in  the  diagram- 
matic drawings  of  Erb.  The  nerve  also  derives  fibers  of 
origin  (see  page  213)  from  the  trineural  bundle  (Spitzka). 
As  the  nerve  emerges  from  between  the  lateral  column  and 
the  restiform  body  of  the  medulla,  its  roots,  between  twelve 
and  fifteen  in  number,  lie  beneath  those  of  the  glosso-pharyn- 
geal nerve.  These  roots  join  to  form  a  flattened  fasciculus 
that  crosses  the  flocculus,  in  company  with  the  glosso-pharyn- 
geal nerve  to  reach  the  jugular  foramen. 

The  ELEVENTH  or  SPINAL  ACCESSORY  NERVE  is  formed  by 


ORIGIN  OF  ELEVENTH  AND   TWELFTH  NERVES.       341 

two  divisions,  the  medullary  and  the  spinal.  The  former  arises 
from  a  nucleus  that  lies  within  the  medulla  close  to  the  cen- 
tral canal  of  the  cord  and  is  a  continuation  downward  of  the 
nucleus  of  the  vagus.  The  spinal  filaments  spring  from  a 
continuation  of  that  nucleus  in  the  gray  substance  of  the 
cord,  as  low  down  as  the  level  of  the  escape  of  the  sixth  or 
seventh  pair  of  cervical  nerves.  The  spinal  filaments  escape 
from  the  lateral  column  of  the  cord,  between  the  anterior  and 
posterior  nerve  roots  of  the  spinal  nerves.  The  medullary 
portion  of  the  nerve  receives  accessory  fibers  from  the  hypo- 
glossal nucleus,  the  solitary  bundle,  and  the  raphe. 

The  TWELFTH  or  HYPOGLOSSAL  NERVE  arises  from  a 
nuclear  column  (about  three  quarters  of  an  inch  in  length) 
that  is  composed  of  large  branching  multipolar  nerve  cells. 
Its  lower  end  is  situated  in  front  of  and  close  to  the  cen- 
tral canal,  in  the  region  of  the  level  of  decussation  of  the 
pyramidal  tracts.  In  the  fourth  ventricle  this  nucleus  forms 
a  prominence  near  the  median  line,  slightly  above  the  cala- 
mus scriptorius.  The  filaments  of  the  nerve  pass  through 
the  inner  side  of  the  olivary  body,  and  emerge  in  the  furrow 
between  the  anterior  pyramid  and  the  olivary  body.  They 
are  then  collected  into  two  bundles  that  join  with  each  other 
to  form  the  nerve  trunk  before  they  reach  the  anterior  condy- 
loid foramen. 

We  are  now  prepared  to  consider  the  separate  cranial 
nerves  and  their  branches  of  distribution. 


THE  OLFACTORY   NERVE. 

The  first  cranial  nerve,  or  nerve  of  smell,  consists  (1)  of 
three  roots  ;  (2)  an  olfactory  process  ;  (3)  a  bulb  ;  and  (4)  ter- 
minal branches,  which  are  distributed  to  the  cavities  of  the 
nose. 

The  three  roots  are  called  the  external^  middle^  and  in- 
ternaU 

^  The  deep  origins  of  this  nerve  have  been  discussed  in  preceding  pages,  as  well  as 
the  probable  situation  of  the  cortical  centers  of  smell. 


342 


THE  CRANIAL  NERVES, 


All  three  of  the  roots  join  to  form  a  band,  which  is  prismoidal 
in  form  (the  olfactory  process  or  tract),  which  passes  forward 


Fio.  76. — Roots  of  tlie  cranial  nen^ea.     (Hirschfcld.) 
T.  First  pair;  olfactory. 
II.  Second  pair;  optic. 

III.  Third  pair;  motor  oculi  communis. 

IV.  Fourth  pair;  patheticus. 

V.  Fifth  pair ;  nerve  of  mastication  and  trifacial. 
VI.  Sixth  pair ;  motor  oculi  externus. 

VII.  Facial,       |.  g.^enth  pair. 
Auditory,  )  ^ 

Glosso-pharyngeal,  ) 
Pneumogastric,        >-  Eighth  pair. 
Spinal  accessory,      ) 
Ninth  pair;  sublingual. 


VIII 

IX 

X. 

XI. 

XII. 


The  numbers  1  to  16  refer  to  branches  which  will  be  described  hereafter. 


along  the  floor  of  the  brain  in  a  deep  sulcus  till  it  expands 
into  the  terminal  enlargement,  known  as  the  *'  olfactory  bulb,'' 
or  "ganglion."  This  terminal  enlargement  lies  upon  the 
upper  surface  of  the  cribriform  plate  of  the  ethmoid  bone, 
through  the  numerous  foramina  of  which  its  branches  escape, 
as  small,  thread-like  filaments ;  which  subsequently  form  a 
plexus  upon  the  surface  of  the  Schneiderian,  or  pituitary^ 
membrane  of  the  nose. 


STRUCTURE  OF  OLFACTORY  FILAMENTS. 

n 


343 


Fig.  '77. —  Olfactory  yaiKjuon  and  nerves.  (Hirschfeld.) 
1,  olfactory  ganglion  and  nerves  ;  2,  branch  of  the  nasal  nerve ;  3,  sphcno-palatine  gan- 
glion ;  4,  7,  branches  of  the  great  palatine  nerve ;  5,  posterior  palatine  nerve ;  6,  mid- 
dle palatine  nerve;  8,  9,  branches  from  the  spheno-palatine  ganglion;  10,11,  12, 
Vidian  nerve  and  its  branches;  13,  external  carotid  branch  from  the  superior  cervical 
ganglion. 

The  filaments  of  the  olfactory  nerve  are  described  by 
Messrs.  Todd  and  Bowman'  as  diifering  in  their  structure 
from  the  ordinary  filaments  found 
in  the  other  cranial  nerves,  in  that 
they  contain  no  white  substance  of 
Schwann,  and  are  nucleated  and  fine- 
ly granular  in  texture.  This  absence 
of  the  white  substance,  found  in 
other  nerves,  renders  it  difiicult  to 
trace  their  course  in  the  Schneiderian 
membrane ;  which  difficulty  is  still 
further  enhanced  by  the  existing  nu- 
clei, w^hich  resemble  those  of  the  tis- 
sues through  which  they  pass. 

The  limit  of  distribution  of  the 
olfactory  nerves  seems  to  be  confined  i, 
to  the  superior  three  fourths  of  the 
septum  of  the  nose,  the  superior  tur- 
binated bone,  the  upper  half  of  the 
middle  turbinated  bone,  and  the  roof 

1  "Physiological  Anatomy." 


Fig.  78. —  Terminal  filaments  of 
the  olfactwy  nei'ves  ;  magnified 
30  diameters.     (Kolliker.) 

1,  from  the  frog — a,  epithelial 
cells  of  the  olfactory  region ; 
6,  olfactory  cells.  2.  Small 
branch  of  the  olfactory  nerve 
of  the  frog,  separating  at  one 
end  into  a  brush  of  varicose 
fibrils.  3.  Olfactory  cell  of 
the  sheep. 


344  THE  CRANIAL  NERVES. 

of  the  nasal  cavities.  These  regions  seem  to  be  defined  by  a 
brown-colored  tesselated  epithelium.* 

Odorous  particles,  present  in  the  inspired  air,  as  they  pass 
through  the  lower  chambers  of  the  nares,  are  diffused  into 
the  upper  nasal  chambers,  and,  falling  upon  the  olfactory 
epithelium,''  produce  sensory  impulses  which  are  transmitted 
to  the  brain  and  give  rise  to  the  sensations  of  smell. 

Forced  inspiration,  or  sniffing,  increases  the  upward  dif- 
fusion of  inspired  air,  and  thus  a  more  complete  contact  of 
the  odorous  particles  is  insured. 

It  seems  that,  for  the  development  of  smell,  the  odorous 
particles  must  be  transmitted  to  the  nasal  mucous  membrane 
in  a  gaseous  medium,  as  the  simultaneous  contact  of  fluids 
destroys  all  appreciation  of  odor." 

Animals  with  a  very  acute  sense  of  smell  have  a  modified 
arrangement  of  the  turbinated  bones,  to  afford  a  larger  ex- 
panse of  surface  than  exists  in  man. 

It  has  been  asserted  by  some  physiologists  that  the  olfac- 
tory nerve  is  not  the  only  nerve  of  smell,  and  Magendie 
claimed  that  animals  could  perceive  the  odor  of  some  sub- 
stances after  the  oKactory  bulbs  had  been  removed.  He  used 
ammonia,  however,  as  a  test  in  his  experiments,  which  is 
hardly  a  test  of  smell,  as  it  is  a  powerful  stimulant  to  the  fifth 
nerve. 

Bernard'  reports  cases  of  absence  of  the  olfactory  bulbs 
in  man,  where  smell  existed  during  life.  Prevost,*  however, 
claims  that  section  of  the  olfactory  bulbs  entirely  destroys  the 
sense  of  smell.  Injury  to  the  fiftli  nerve  may  also  destroy 
smell,  even  where  the  olfactory  nerve  remains  intact ;  but  this 
effect  is  hardly  a  proof  that  the  nerve  is  in  any  way  related  to 
that  special  sense,  since  the  effect  is  probably  due  to  an  altered 
condition  of  the  nasal  mucous  onemhrane^  which  prevents  its 
performing  its  natural  function.  The  loss  of  smell  may, 
therefore,  be  of  some  diagnostic  value,  if  associated  with  other 
symptoms  referable  to  impairment  of  the  fifth  cranial  nerve. 

'  Max  Schultze.  »  Mich.  Foster,  "  Text-Book  of  Physiology." 

'  *  "  Syst.  nerv.,"  vol.  ii.  *  "  Archives  de  sci.  phys.  et  nat.,"  1871. 


THE  PERCEPTIONS  OF  ODOR, 


345 


It  seems  necessary,  in  all  animals  which  live  in  the  air, 
that  all  odorous  materials  must  enter  the  nostril  to  be  per- 
ceived, and,  furthermore,  that  the  membrane  of  the  nose  must 
be  in  a  proper  condition  of  moisture ;  hence,  by  breathing 
through  the  mouth,  the  most  disagreeable  of  odors  may  usu- 
ally be  unperceived,  and  the  blunted  sensibility  of  the  power 
of  smell,  which  occurs  in  catarrh,  may  plausibly  be  explained 
as  the  result  of  a  deficient  secretion  in  the  early  stage  of  the 
attack,  and  of  excessive  secretion  later  on  in  the  disease. 
The  curious  effects  of  section  or  injury  of  the  fifth  cranial 
nerve  upon  the  sense  of  smell  may  justly  be  attributed  to  the 
alteration  in  the  amount  of  secretion  of  the  lining  membrane 
of  the  nose,  since  this  nerve  exerts  a  marked  influence  upon 
the  secretions  of  the  tissues  supplied  by  it. 


vniW    IV  V 


Fig.  79. — Inta-nal  brcmchcs  of  the  olfador;^  nerve.     (After  Sappcy.) 

1,  internal  brnnehes  of  the  olfactory  bulb,  ramifying  in  the  mucous  membrane  covering 
the  septum  of  the  nasal  fossae ;  2,  internal  branch  of  the  ethmoidal  division  of  the 
nasal  nerve;  3,  naso-palatine  nerves;  4,  5,  6,  cavernous  plexus;  7,  superior  or 
ascending  branches  of  this  plexus ;  8,  internal  carotid  branch  from  the  superior  cer- 
vical ganglion;  9,  9,  filaments  connecting  this  branch  with  the  external  carotid 
branch  ;  10,  origin  of  this  branch;  11,  ganglion  of  the  glosso-pharyngeal ;  12,  jugu- 
lar ganglion  of  the  pneumogastric ;  13,  anastomotic  filaments  extending  from  the 
sympathetic  to  the  two  preceding  nerves  ;  14,  anastomosis  of  the  spinal  accessory 
with  the  pneumogastric;  15,  filament  connecting  the  sympathetic  with  the  hypo- 
glossal; I,  olfactory;  II,  optic;  III,  motor  oculi ;  IV,  patheticus  ;  V,  trigeminus; 
VI,  abduccns ;  VII,'  facial ;  VIII,  auditory ;  IX,  glosso-pharyngeal ;  X,  pneumogas- 
tric ;  XI,  spinal  accessory ;  XII,  hypo-glossal. 

The  act  of  sneezing,  by  which  a  forcible  blast  of  air  is 
driven  through  the  nostrils,  is  often  an  effort  on  the  part  of 
Nature  to  get  rid  of  some  irritating  substance  ;  and  thus, 


346  TEE  CRANIAL  NERVES. 

through  the  agency  of  the  fifth  nerve,  is  the  nose  made  the 
portal  of  the  respiratory  apparatus^  where  cognizance  of  the 
quality  of  the  air  breathed  is  constantly  taken,  and  where  all 
foreign  or  injurious  matters  are  at  once  detected,  and  often 
expelled. 

A  marked  peculiarity  of  the  olfactory  nerve  is  shown  by 
the  fact  that  no  form  of  irritation  of  its  fibers  excites  reflex 
muscular  action  through  other  nerves  ; '  neither  is  it  capable 
of  the  sensation  of  pain,  since  section  of  the  nerve,  or  even  the 
destruction  of  the  olfactory  ganglia,  seems  to  create  no  special 
distress  in  animals,  and  the  nose  retains  its  normal  sensitive- 
ness until  the  fifth  nerve  is  also  divided. 

The  olfactory  nerve,  however,  may  be  the  source  of  another 
variety  of  marked  reflex  action.  Many  cases  are  recorded 
where  fainting  and  vomiting  have  been  produced  by  certain 
odors ;  while,  for  some  unexplained  reason,  mental  associa- 
tions cluster  around  sensations  of  smell  more  strongly  than 
any  other  form  of  impression  received  from  without.'' 

The  importance  of  the  sense  of  smell  among  many  of  the 
lower  animals,  in  guiding  them  to  their  food,  or  in  giving 
them  warning  of  danger,  and  also  in  exciting  the  sexual  feel- 
ings, is  well  known.  Among  the  savage  tribes,  whose  senses 
are  more  cultivated  than  those  of  civilized  nations,  the  scent 
is  almost  as  acute  as  in  the  lower  mammalia.  It  is  asserted  by 
Humboldt  that  the  Peruvian  Indians,  in  the  middle  of  the 
night,  can  thus  distinguish  the  different  races,  whether  Euro- 
pean, American,  Indian,  or  Negro. 

The  agreeable  or  disagreeable  character  assigned  to  any 
particular  odor  is  by  no  means  constant  among  different  indi- 
viduals. Many  of  the  lower  animals  pass  their  whole  lives 
in  the  midst  of  odors  which  are  to  man  (in  a  civilized  condi- 
tion) in  the  highest  degree  revolting,  and  will  even  refuse  to 
touch  food  until  it  is  far  advanced  in  putridity.' 

^  Carpenter,  "  Principles  of  Physiology."     The  act  of  vomiting  may  possibly  be  con- 
sidered as  an  exception  to  this  statement. 

2  Mich,  Foster,  "  Text-Book  of  Physiology,"  1880 ;  Todd  and  Bowman,  "  Physiologi- 
cal Anatomy." 

3  Carpenter,  "  Principles  of  Human  Physiology." 


ABNORMALITIES  OF  THE  OLFACTORY  SENSE.  347 

It  is  difficult  to  say  wlien  effluvia  have  been  completely 
removed  from  the  nasal  passages,  since  it  is  not  unlikely  that 
odorous  particles  (supposing  such  to  exist)  are  often  ab- 
sorbed, or  possibly  dissolved  by  the  mucous  secretion.  It 
frequently  happens,  in  regard  to  odors  and  savors,  that  habit 
makes  that  agreeable,  and  even  strongly  relished,  which  was 
at  first  avoided  ;  the  taste  of  an  epicure  for  game  that  has 
acquired  ihe  fumet^  for  assafoetida,  garlic,  etc.,  is  an  instance 
of  this.  A  case  is  reported,  where,  in  a  state  of  hypnotism,  a 
youth  had  his  sense  of  smell  so  remarkably  heightened  as  to 
be  able  to  assign,  without  the  least  hesitation,  a  glove  placed 
in  his  hand  to  its  right  owner,  in  the  midst  of  about  thirty 
persons,  the  boy  himself  being  blindfolded  ; '  and  modified 
forms  of  this  excessive  development  of  this  power  of  smell 
are  by  no  means  rare. 

The  word  ''taste"  is  often  used  when  the  word  ''smell" 
should  be  employed.  We  speak  of  tasting  odoriferous  sub- 
stances, such  as  onions,  vdnes,  etc.,  when  in  reality  we  only 
smell  them  as  we  hold  them  in  the  mouth.  This  is  proved  by 
the  fact  that  the  so-called  taste  of  these  things  is  lost  when 
the  nose  is  held  or  the  nasal  membrane  rendered  inert  by  a 
catarrh. '^ 

CLIKICAL   POINTS   AFFORDED   BY  THE   OLFACTORY   KERVE. 

The  nerves  of  smell  may  become  the  seat  of  disease,  or  may 
simply  manifest  the  presence  of  disease  in  other  parts.  The 
two  conditions,  which  are  clinically  recognized  as  indicative  of 
existing  disease,  are  hypersesthesia  and  anaesthesia — ^not  of 
the  sensibility  of  the  part,  in  its  generally  accepted  sense,  but 
an  increase  or  decrease  of  the  acuteness  of  the  olfactory  sense/ 

^  Carpenter,  op.  cit. 

'*  Foster,  op.  cit. 

3  According  to  Althaus,  if  the  mucous  membrane  of  the  nose  be  irritated  with  very 
strong  galvanic  currents,  the  taste  of  phosphorus  is  produced ;  but  no  perception  of  odors 
is  perceived,  although  pain,  vertigo,  and  sensations  of  light  may  be  created.  It  is  cus- 
tomary, therefore,  to  use  other  means  for  the  purpose  of  testing  the  acuteness  of  this 
special  sense,  and  the  most  successful  method  consists  of  making  the  patient  smell  differ- 
ent odors,  using  the  nostrils  alternately,  and  avoiding  all  things,  as  tests,  which  would  create 
an  irritation  of  the  filaments  of  the  fifth  nerve,  such  as  ammonia,  acetic  acid,  snuff,  etc. 
(Hence  the  defect  in  Magendie's  experiments  mentioned  on  page  344.)    It  is  advisable 


348  THE  CRANIAL  NERVES. 

To  the  former  condition,  the  term  '' hyper o^mia''''  is  applied, 
while  the  latter  is  called  ^'anosmia.''' 

The  condition  of  hyperosmia  is  often  perceived,  as  a  tem- 
porary excitation,  in  patients  recovering  from  some  prolonged 
disease  which  has  exhausted  their  nervons  power,  and  also 
in  the  hysterical  and  insane.'  Should  the  presence  of  un- 
natural odors,  or  a  marked  increase  of  the  susceptibility  to 
odors,  exist  in  the  insane,  it  may  indicate  the  existence  of 
some  type  of  neoplasm  involving  the  frontal  lobes  at  the  base 
of  the  cerebrum,  localized  disease  (softening,  as  a  rule)  of  the 
olfactory  bulbs,  or  adhesion  of  the  olfactory  bulbs  to  the  dura 
mater ;  since  all  of  these  conditions  have  been  found  at  autop- 
sies, where  such  symptoms  existed  during  life.  Sander 
reports  a  curious  case,  where  such  a  subject  was  liable  to 
epileptic  attacks,  and  where  the  attacks  were  associated  with 
abnormal  sensations  of  taste ;  the  autopsy  showed  a  tumor 
of  the  left  olfactory  bulb. 

The  abolition  of  the  sense  of  smell  is  a  symptom  of  greater 
frequency,  as  well  as  importance,  than  the  excitation  of  that 
special  sense.  In  rare  cases,  as  in  one  reported  by  Cloquet, 
the  absence  of  the  power  of  smell  may  be  a  congenital  defect. 
Anosmia  may  be  developed,  as  a  temporary  condition,  during 
an  attack  of  acute  catarrhal  inflammation  of  the  nares,  which 
alters  the  character  of  the  membrane,  or,  in  chronic  catarrh, 
by  the  effect  upon  the  natural  moisture  of  the  mucous  lining 
of  the  nose.  It  may  be  present  in  ^'  Bell's  paralysis,"'  since 
the  facial  nerve  no  longer  affords  motor  power  to  the  muscles 
which  dilate  the  nostril,  and  thus  the  entrance  of  air  to  the 
upper  nasal  chamber  is  obstructed.     Anosmia  may  be  one  of 

to  use  odors  which  are  both  agreeable  and  disagreeable ;  hence  cologne,  camphor,  musk, 
etc.,  on  the  one  hand,  and  valerian,  assafoetida,  turpentine,  sulphureted  hydrogen,  etc.,  on 
the  other  hand,  are  commonly  employed.  It  is  also  customary  to  place  aromatic  substances^ 
such  as  coflfee,  wine,  liquors,  and  cheese,  within  the  mouth,  so  that  the  posterior  part  of 
the  nose  can  perceive  them,  since  the  odoriferous  particles  pass  upward  by  means  of  the 
pharynx,  rather  as  an  imaginary  taste,  however,  than  as  true  olfactory  perceptions. 

'  Frequently  odors  of  the  most  pleasant  character,  such  as  those  of  flowers,  etc.,  may 
occasion  fainting,  nausea,  headache,  or  even  convulsions,  in  this  class  of  patients  ;  while 
odors  nauseating  to  others  may  be  tolerated,  and,  possibly,  preferred  by  them. 

*  For  the  symptoms  of  this  affection,  see  pages  of  this  volume  descriptive  of  the  facial 


THE  NERVE  OF  VISION.  349 

the  manifestations  of  tumor  at  the  base  of  the  brain ;  of  ab- 
scess of  the  pituitary  body  (as  reported  by  Oppert) ;  of  syphi- 
litic thickening  of  the  periosteum  and  mucous  lining  of  the 
nose ;  of  lesions  resulting  in  paralysis  of  the  fifth  cranial 
nerve,  for  some  unexplained  reason  ;  of  hysteria  ;  and,  finally, 
of  certain  types  of  insanity.  A  partial  loss  of  smell  has  been 
known  to  follow  typhoid  fever  and  meningitis,  in  which  case 
the  sense  is  usually  regained.  Chronic  rheumatism,  chronic 
rhinitis,  and  traumatism,  have  also  proven  exciting  causes  of 
a  temporary  but  serious  loss  of  the  sense  of  smell. ' 


THE  OPTIC 'NERVE. 

The  second  cranial  or  optic  nerve  presents  for  examination 
from  before  backward :  1,  the  optic  nerve  proper ;  2,  the  op- 
tic commissure  ;  and  3,  the  optic  tract. 

The  optic  tracts  of  either  side  extend  from  their  point  of 
apparent  origin  in  the  anterior  corpora  quadrigemina.,  where 
they  receive  fibers  from  the  optic  thalamus  and  the  external 
geniculate  bodies,'  to  the  optic  commissure,  to  reach  which 
point,  each  is  compelled  to  pass  around  the  cms  cerebri.  In 
their  passage  around  the  cms,  each  tract  receives  a  few  fibers 
of  attachment  at  its  anterior  margin ;  and,  after  leaving  the 
cms,  just  before  the  optic  chiasm  is  formed,  each  receives 
additional  fibers  from  the  lamina  cinerea  and  the  tuber 
cinereum 

The  optic  commissure  or  chiasm  is  formed  by  the  junc- 
tion of  the  two  optic  tracts,  and  from  it  the  two  optic  nerves 
diverge  to  pass  to  their  distribution  in  the  retina  of  either 
eye.  The  construction  of  the  optic  chiasm  is  of  interest  both 
from  an  anatomical  and  a  physiological  standpoint.  In  it, 
four  sets  of  fibers  may  be  demonstrated,  called,  respectively, 

'  In  almost  all  cases,  where  anosmia  affects  both  sides  of  the  nasal  cavity,  the  sense 
of  taste  is  also  impaired.  All  aromatic  forms  of  food  and  wines  have  a  distorted  flavor. 
It  is  claimed  by  Ogle  that  the  pigment  in  the  olfactory  mucous  membrane  has  some  effect 
upon  the  sense  of  smell. 

^  Physiological  experiment  seems  to  point  to  the  occipital  cortex  as  intimately  con- 
nected with  the  deep  fibers  of  the  optic  nerve,  as  mentioned  in  the  preceding  section. 
25 


350 


THE  CRANIAL  NERVES. 


30^ 


the  inter -cerebral  fibers,  which  are  situated  at  the  poste- 
rior portion  of  the  commissure,  and  connect  the  two  hemi- 
spheres of  the  cerebrum ;  the  in- 
ter-retinal fibers  (?),  which  are  situ- 
ated in  the  anterior  portion  of  the 
chiasm,  and  connect  the  retina  of 
one  eye  with  that  of  the  other ;  the 
longitudinal  fibers^  which  lie  on 
the  external  side  of  each  of  the 
optic  tracts,  and  connect  the  ret- 
ina with  the  cerebral  hemisphere 
of  the  same  side ;  and,  finally, 
the  decussating  fibers,  which  pass 
through  the  center  of  the  optic 
chiasm,  and  serve  to  connect  the 
retina  of  each  eye  with  the  oppo- 
site cerebral  hemisphere. 

The  optic  nerve  proper  arises 
from  the  anterior  part  of  the  optic 
commissure  and  enters  the  optic 
foramen,  in  company  with  the  oph- 
thalmic artery,  being  surrounded 
by  a  tubular  process  of  dura  mater, 
which,  as  the  nerve  enters  the  or- 
bit, subdivides  and  forms  both  the 
sheath  of  the  nerve  and  the  peri- 
osteum of  the  orbit.  The  nerve 
pierces  the  sclerotic  and  choroid  coats  of  the  eye,  about  one 
tenth  of  an  inch  to  the  inner  side  of  the  axis  of  the  eye,  and 
then  divides  into  numerous  small  fibrils,  which  appear  to 
spread  themselves  out  from  the  papilla  of  the  retina  some- 
what like  the  spokes  of  a  wheel. 

In  the  accompanying  diagram,'  which  is  not  given  as  an 
accurate  representation  of  the  parts,  but  rather  as  an  aid  to 
memory,  and  to  render  plain  what  words  alone  might  make 
obscure,  the  fibers  of  \\iQ  optic  nerve  are  seen  to  enter  the  re- 


Fio.  80. —  Optic  tracts,  commissure, 
and  nerves.     (Hirschfeld.) 

1,  infundibulura  ;  2,  corpus  cinere- 
um  ;  3,  corpora  albicintia ; 
4,  cerebral  peduncle ;  5,  tuber 
annulare  ;  6,  optic  tmcts  and 
nerves,  decussatiny  at  the  com- 
missure, or  chiasm ;  1,  motor 
oculi  communis  ;  8,  pathetieus ; 
9,  fifth  nerve ;  10,  motor  oculi 
externns  ;  11,  facial  nerve ;  12, 
auditory  nerve;  13,  nerve  of 
Wrisberg  ;  14,  glosso-pharyn- 
geal  nerve  ;  16,  pneumogastrie ; 
16,  spinal  accessory;  17,  sub- 
lingual norve. 


*  After  Weber,  of  Darmstadt.     (See  page  351.) 


DISTRIBUTION  OF  OPTIC  FIBERS. 


351 


tina  at  the  point  designated  by  the  letter  P,  which  is  called 
the  papilla^  since,  at  this  point,  the  retina  is  slightly  raised 
above  the  remaining  portion.  This  papilla  is  not  in  the  exact 
center  of  the  retina,  since  that  point  is  reserved  for  the  macula 
lutea^  in  the  center  of  the  so-called  ''  yellow  spot  of  Sommer- 
ing,"  where  the  most  exact  vision  of  external  objects  is  ob- 


FiG.  81. — Diagram  of  the  decussation  at 
the  optic  commissure.    (After  Flint.) 

The  dotted  lines  show  the  four  direc- 
tions of  the  fibers. 


Fig.  82. — A  diagram  to  show  the  course  of 
the  optic  fibers  in  the  retina.  (After  Weber.) 

p,  the  papilla,  where  the  optic  nerve  enters ; 
M,  the  macula  lutea. 


tained ;  but  it  is  placed  to  the  inner  side  of  the  center^  and 
nearly  on  the  same  level  with  the  yellow  spot.  It  will  be  seen 
that  those  nerve  fibers  which  are  distributed  around  the  yellow 
spot  of  Sommering  are  directed  outward  in  a  nearly  straight 
line  from  the  papilla,  as  are  also  those  which  supply  the  part 
internal  to  the  papilla  ;  but  that,  in  order  to  avoid  crossing 
the  yellow  spot,  the  fibers  are  compelled  to  pass  in  a  more 
or  less  curved  direction  to  the  other  parts  of  the  retina, 
whereas,  if  the  papilla  were  in  the  exact  center,  the  fibers 
of  the  optic  nerve  would  probably  have  been  straight,  and 
arranged  as  the  radii  of  a  circle.  This  arrangement  of  the 
optic  fibers  differs  from  that  described  by  some  of  the  text- 
books on  physiology,  one  of  which,  to  my  knowledge,  states 
that  they  are  arranged  as  a  plexus,  and  that  the  frequent 
inosculation  gives  a  peculiar  '^ net-like"  appearance  to  the 


352  THE  CRANIAL  NERVES. 

optic  fibers/  Probably  the  fact  that  the  nerve  fibers  lose 
their  sheaths  as  soon  as  they  enter  the  retina,  and  thus, 
unless  they  be  previously  stained,  afford  some  difficulty  in 
tracing  them,  explains  the  error  in  description. 

REFLEX   ACTS   EXCITED   BY  THE   OPTIC   KERVE. 

The  optic  nerve  differs  from  the  olfactory  nerve  in  one  im- 
portant respect,  viz.,  in  its  power  of  conveying  impressions 
which  create  reflex  muscular  movements."  The  motions  of  the 
iris  are  always  influenced  by  the  amount  of  light  which  enters 
the  eye,  and  which  thus  affects  the  optic  nerve  filaments. 
When  the  optic  nerve  is  divided,  the  pupil  immediately  con- 
tracts, unless  the  third  cranial  nerve,  which  controls  its  move- 
ments, is  also  severed,  when  the  iris  fails  to  be  so  affected.' 
In  rare  cases  of  disease,  where  the  sight  of  one  eye  has  been 
destroyed  by  some  lesion  of  the  optic  nerve,  the  pupil  of  the 
affected  eye  will  be  found  to  move  in  unison  with  the  unin- 
jured eye  ;  but  this  effect  is  to  be  attributed  to  a  motor  impulse 
created  by  the  influence  of  light  upon  the  retina  of  the  normal 
organ.  In  some  cases  also,  where  the  tissue  of  the  cerebral 
hemispheres  has  undergone  changes  which  render  the  percep- 
tion of  objects  impossible,  the  pupil  may  still  be  seen  to  re- 
spond to  the  variations  of  the  quantity  of  light  which  enters 
the  chamber  of  the  eye ;  thus  showing  that  the  optic  nerve 
alone  is  required  to  create  the  reflex  act  upon  the  pupil 
through  the  third  nerve,  irrespective  of  the  brain. 

In  addition  to  the  power  of  the  optic  nerve  to  cause 
changes  in  the  pupil,  there  is  still  another  form  of  reflex  act 
which  deserves  notice,  viz.,  its  power  of  producing  contraction 
of  the  orbicularis  palpebrarum  muscle.  This  is  perceived 
when  an  excessive  quantity  of  light  renders  the  effect  upon 

^  Carpenter,  op.  cit. 

'  Carpenter,  op.  cit.  (It  is  a  question  M  fainting  and  vomiting  can  not  be  often  justly 
regarded  as  reflex  muscular  acts,  dependent  upon  the  sensations  perceived  through  the 
olfactory  nerve.) 

^  Doubtless  on  account  of  the  simultaneous  division  of  sympathetic  nerve  fibers,  which 
are  probably  derived  from  the  fifth  nerve  ;  these  accompany  the  optic  nerve  and  thus  con- 
trol the  dilating  fibers  of  the  iris. 


I 


DECUSSATION  OF  OPTIC  FIBERS.  353 

the  retina  one  of  pain,  or  when  objects  to  be  perceived  are 
brought  into  too  close  proximity  to  the  eye.  Thus,  in  photo- 
phobia, the  peculiar  half- closed  condition  of  the  eye  is  not 
purely  a  voluntary  act,  as  the  eye  is,  at  the  same  time,  rolled 
upward  and  inward  to  a  much  greater  extent  than  can  be  per- 
formed in  response  to  a  merely  voluntary  effort. 

The  act  of  sneezing  may  often  be  excited  by  the  visual 
sense,  when  a  sudden  exposure  of  the  eyes  to  a  strong  light 
occurs.  That  this  reflex  phenomenon  is  due  to  the  excitation 
of  the  optic,  and  not  to  the  olfactory  nerve,  is  proven  by  the 
fact  that,  unless  the  light  he  seen,  the  attack  of  sneezing  does 
not  take  place. 

DECUSSATION   OF  THE   OPTIC   FIBERS. 

The  object  of  the  decussation  of  the  fibers  of  the  optic 
nerve  has  been  explained  by  WoUaston,'  Mayo,''  and  others, 
as  an  arrangement  on  the  part  of  Nature  to  have  the  fibers, 
which  spring  from  each  optic  ganglion,  distributed  to  the  cor- 
responding side  of  each  retina  ;  the  right  optic  ganglion  be- 
ing thus  associated  with  the  outer  portion  of  the  retina  of  the 
right  eye  and  the  inner  ^portion  of  the  left  eye,  while  the  left 
ganglion  is  distributed  to  the  outer  portion  of  the  left  eye 
and  the  inner  portion  of  the  right  eye.  If  this  be  demon- 
strated as  true,  each  optic  ganglion  must  perceive  objects  on 
the  side  opposite  to  it ;  since  the  images  of  things  seen  by  the 
retina  must  fall  upon  the  outer  side  of  the  left  eye,  when 
placed  upon  the  right  side  of  the  eye,  and  vice  versa." 

A  similar  decussation  of  nerve  fibers  is  known  to  exist  in 
both  the  posterior  horns  of  the  spinal  cord  and  also  in  the 
anterior  pyramids  of  the  medulla  oblongata  ;  and  the  same 
arrangement  in  the  optic  nerves,  which  are  known  to  be  of 
the  greatest  value  in  preserving  a  harmony  of  motion  through- 
out the  body,  may  be  for  the  object  of  bringing  the  visual  im- 
pressions into  a  more  direct  and  proper  accord  with  the  motor 

'  "  Philos.  Trans.,"  1824. 
'^  See  Carpenter's  "  Physiology," 

^  See  bearing  of  this  arrangement  on  diagnosis  of  cranial  tumors,  later  on  in  this 
chapter. 


354  THE  CRANIAL  NERVES. 

apparatus.  In  support  of  this  view,  it  is  found  that  ia  the 
invertebrate  animals,  where  the  optic  fibers  do  not  decus- 
sate, no  decussation  of  fibers  exists  in  the  general  motor 
system. 

In  some  animals,  where  the  two  eyes  have  an  entirely  dif- 
ferent field  of  vision,  the  decussation  of  the  fibers  from  each 
optic  ganglion  is  found  to  be  complete,'  the  longitudinal  set 
being  absent,  and  the  whole  of  the  fibers  from  each  ganglion 


^.AOA.    o.n.-  -.         ..         .  »       OPTIC  NERVE 

NASAL  SIDE 


or  OPTIC    --• 
FORAMEN.  V       ^^^Z"      .     A    /    OPHTHALMIC 

ARTERT. 


Fig.  83. — Relation  of  nei've  and  artei'y  in  the  optic  foramen^ 
1 


2 
OPTIC  NERVE. 


I.2.3.4.5.CILIAFY  ARTERIES. 
Fig.  84. — Relations  of  optic  nerve  to  vessels  in  the  orbit. 

passing  into  the  opposite  eye.  This  arrangement  can  be  per- 
ceived in  almost  all  of  the  bird  species "  and  in  some  of  the 
osseous  fishes. 

RELATIONS   OF  OPTIC   NERVE  IN  THE   ORBIT. 

The  relations  of  the  optic  nerve  to  hlood-vessels  may  have 
often  a  bearing  upon  vision.     It  passes  through  the  optic 

*  The  decussation  of  the  fibers  of  the  optic  nerve  seems  also  to  be  influenced  largely 
by  tho  extent  of  the  field  of  vision  which  can  be  covered  by  both  ei/cs  simultaneously. 
The  bundle  of  decussating  fibers  differs,  in  its  relative  size,  from  the  bundle  of  non-de- 
cussating fibers,  in  different  animals,  who  possess  a  stereoscopic  perception  of  objects 
(their  vision  being  binocular) :  and  the  extent  of  the  field  of  binocular  vision  seems  to 
explain  this  fact.  It  is  said  that  certain  birds  (as  the  hawk,  for  example)  have  an  addi- 
tional power  of  vision  afforded  them  by  means  of  two  maculae  luteae  in  each  retina ;  so 
that,  having  two  spots  of  distinct  vision  in  each  eye,  the  eye  can  the  more  readily  focus 
suddenly  upon  any  object. 

'  Solly,  "  The  Human  Brain  "  (Am.  edition). 


RESULTS  OF  DEFECTIVE  VISION.  355 

foramen  in  company  with  the  ophthalmic  artery,  and  is  sur- 
rounded, for  the  balance  of  its  length,  by  the  ciliary  arteries, 
which  lie  in  close  relation  with  it.  It  is  also  pierced  by  the 
arteria  centralis  retince.,  which  is  thus  enabled  to  reach  the 
papilla  of  the  retina,  and,  from  that  point,  to  ramify  through- 
out that  membrane. 

It  can  be  readily  understood,  therefore,  how  any  vascular 
growth  within  the  orbit  would  be  liable  to  press  upon  the 
fibers  of  the  optic  nerve,  or  to  create  sympathetic  changes  in 
the  vessels  of  the  retina  itself ;  while,  as  an  anatomical  fact, 
the  enormous  collateral  circulation  which  exists  on  account 
of  the  frequent  anastomosis  in  this  region,  renders  such  vas- 
cular growths  within  the  orbit  by  no  means  uncommon. 

AlS^ATOMICAL   DEFECTS   OF   VISION"   AKD  THEIR   CO]srSEQUE]!^CES. 

A  ray  of  light  falling  upon  the  retina  strikes  the  expansion 
of  the  fibers  of  the  optic  nerve,  and  creates  what  may  be  called 
a  sensation  of  light.  What  this  sensation  is,  it  is  not  within 
the  province  of  this  work  to  discuss,  nor  is  it  possible,  from 
our  present  enlightenment,  to  explain  how  the  brain  trans- 
forms impressions,  received  from  the  fibers  of  the  different 
nerves  of  special  sense,  into  an  actual  recognition  of  either 
smell,  sight,  taste,  or  hearing.  This  should  not  deter  us,  how- 
ever, from  carefully  studying  all  the  mechanical  ingenuity 
which  Nature  has  shown  in  the  arrangement  of  certain  parts, 
or  from  attempting  to  interpret  her  aims  and  purposes  when 
any  such  subject  of  inquiry  seems  to  be  presented. 

There  are  certain  practical  points  pertaining  to  the  mechan- 
ism of  vision  concerning  which  every  physician  should  be  in- 
telligent ;  since  a  recognition  of  existing  optical  defects  and 
their  bearings  upon  health  will  often  enable  the  medical  ad- 
viser to  guide  aright  those  consulting  him,  when  otherwise 
serious  consequences  might  follow  the  very  lack  of  this  prac- 
tical knowledge. 

The  most  common  optical  defects '  are,  undoubtedly,  hy- 
peropia, or  far-sightedness;   myopia,   or  near-sightedness; 

^  Bowman  and  Todd,  "  Physiological  Anatomy." 


356  THE  CRANIAL  NERVES, 

and  astigmatism^  causing  imperfect  perception  of  objects  in 
certain  meridians  of  vision. 


Fig.  85. — Diagram  to  illustrate  congenita!  or  acquired  defects  in  the  antero-posterior  diam- 
eter of  the  eye.  The  black  line  represents  the  normal  line  of  the  eye.  No.  1  repre- 
sents the  hyperopic  eye ;  2,  the  myopic  eye ;  3,  the  optic  nerve. 

The  first  of  these  conditions  indicates,  as  a  rule,  a  congeni- 
tal or  acquired  diminution  in  the  antero-posterior  axis  of  the 
eye.  Thus,  as  age  advances,  the  eye  either  naturally  be- 
comes flattened,  or  the  ability  to  accommodate  for  distance  be- 
comes impaired,  and  vision  necessarily  becomes  presbyopic  ; 
but,  in  many  cases,  children  are  bom  with  this  deformity, 
which  often  goes  too  long  unrecognized.  Were  Nature  not 
able  to  compensate  for.  this  abnormality  by  means  of  the  cili- 
ary muscle,  which,  by  altering  the  shape'  of  the  crystalline 
lens  of  the  eye,  is  enabled  to  increase  its  convexity,  and  thus 
artificially  to  focus  near  objects,  such  cases  would  be  imme- 
diately made  known  by  the  inability  of  the  patient  to  read 
or  even  to  see  near  objects  with  distinctness.  But  such  cases 
go  on  from  year  to  year,  struggling,  with  the  aid  of  this  mus- 
cle, to  see,  and  thus  wearing  out  their  vital  energy ;  trying 
to  excel  in  their  studies,  only  to  fail  from  the  fatigue  which 
attempts  at  study  bring  about,  which  they  themselves  or  their 
parents  can  not  explain,  and  which  often  causes  them  to  in- 
cur bodily  chastisement ;  and  seeking,  as  a  relief,  out-of-door 
amusements,  in  which  they  usually  excel,  since  little  muscu- 
lar effort  is  required  to  perceive  objects  at  a  distance. 

'  Foster,  Volckers,  Hensen,  and  Hock  claim  that  the  increased  convexity  of  the  lens 
is  due  to  the  relaxation  of  the  suspensory  ligament,  thus  allowing  the  lens  to  bulge  for- 
ward from  its  own  elasticity. 


RESULTS   OF  DEFECTIVE  VISION.  35Y 

How  cruel  and  injurious  to  health  must  be  compulsory 
education  to  such  a  one,  till,  by  the  aid  of  properly  adjusted 
glasses,  reading  becomes  a  pleasure ;  study  no  longer  a  bur- 
den, but  a  joy  ;  and  nervous  headache,  throbbing  in  the  orbit, 
double  vision,  and  other  evidences  of  nervous  prostration,  are 
numbered  as  among  the  things  of  the  past ! ' 

On  the  other  hand,  myopic  patients  can  not  see  objects  at 
a  distance,  since  their  eyes  are  too  convex ;  but  only  when 
placed  close  to  the  eyes  are  the  beauties  of  outline  fully  per- 
ceived, and  distinct  vision  rendered  possible.  Out-of-door 
exercise  is,  to  children  of  this  type,  a  burden  and  a  disap- 
pointment, since  they  can  not  enjoy  Nature  in  her  most  beau- 
tiful aspects,  nor  indulge  in  sports  without  danger,  which  to 
the  healthy  child,  with  perfect  vision,  is  harmless.  Such 
children  seek  enjoyment  in  books,  the  contents  of  which  can 
be  seen  by  them  and  easily  read ;  the  fields  are  discarded  for 
the  parlor ;  the  enforced  retirement  is  wrongly  construed  by 
the  parents  and  physician  as  an  indication  of  precocity  and  a 
taste  above  that  of  the  romping  child ;  the  health  is  imper- 
iled, the  intellect  weakening  by  undue  strain,  and  the  mind 
made  one  of  ideals  rather  than  of  realities,  since  pictures  and 
book  representations  are  to  them  Nature  in  her  true  aspects.' 

Astigmatism  is  a  condition  due  to  the  fact  that  either  the 
surfaces  of  the  cornea  or  of  the  crystalline  lens  are  not  of  the 
same  curvature^  but  are  more  convex  in  some  portions  than 
in  others,  or  in  the  perpendicular  meridian  than  in  the  hori- 
zontal. This  abnormality  of  contour  causes  a  distortion  of 
the  image  of  objects  in  the  field  of  vision.  If  black  lines,  of 
equal  width,  be  drawn  parallel  with  each  other,  and  several 
placed  perpendicularly  on  one  portion  of  a  page  and  several 
horizontally  on  another  portion  of  the  same  page,  such  an  eye 
will  see  one  or  the  other  set  either  less  distinctly  as  to  outline, 
or  one  set  will  appear  darker  than  the  other. 

Almost  all  eyes  are  slightly  astigmatic,  and  generally  with 
the  greatest  convexity  in  the  vertical  meridian.  And  the  same 
irregularity  in  lenses  can  be  demonstrated  by  attempting  to 

^  See  article  by  Dr.  Loring,  "  Harper's  Mag.,"  August,  1879. 


358  THE  CRANIAL  NERVES. 

focus  light  from  a  luminous  point,  when  the  image  will  be 
found  to  be  radiated,  instead  of  a  perfect  circle,  as  it  should 
be  from  a  perfect  lens. 

In  choosing  spectacles,  for  the  purpose  of  correcting  errors 
of  the  eye,  it  is  of  great  consequence  not  to  make  an  over- 
compensation ;  for  this  has  a  tendency  to  increase  the  defect, 
besides  occasioning  great  fatigue  in  the  employment  of  the 
sight. 

From  observations  previously  made  as  to  the  mechanism 
of  the  action  of  the  ciliary  muscle  upon  the  lens,  by  which 
vision  is  accommodated  for  near  objects  in  case  the  eye  is 
normal,  it  may  be  understood  why  all  power  of  accommoda- 
tion of  vision  is  lost  after  the  operation  for  cataract. 

A   TEST   FOR   MYOPIA   AND   HYPEROPIA. 

B  F  P  T  Z  D 
D  I.  T  Z  F  F  E 
B  E  P  F  Z  T  I. 

The  normal  eye  should  read  letters  of  this  kind  and  size 
at  twenty  feet.  Vision  is  then  said  to  be  normal.  If  the  eye 
can  not  do  this  at  twenty,  but  can  at  ten  feet,  then  vision  is 
ten  twentieths,  or  one  half  of  the  normal,  and  so  on. 

To  test  the  eyes,  place  the  letters  at  twenty  feet  dis- 
tance, in  a  good  light.  Try  first  one  eye,  and  then  the 
other. 

Any  eye  which  can  not  read  the  letters  fluently  at  this  dis- 
tance deviates  from  the  normal  standard,  and  should  have  a 
thorough  examination. 

To  test  for  the  defect  which  has  been  mentioned  in  the 
foregoing  remarks  as  astigmatism,  place  the  drawing,  show- 


TESTS  FOR  DEFECTIVE   VISIOK 


359 


ing  parallel  lines  arranged  vertically  and  horizontally,  at  fif- 
teen or  twenty  feet,  and  be  sure  to  test  each  eye  separately. 


A  TEST   FOR   ASTIGMATISM. 


These  lines  should  appear  equally  distinct ;  that  is,  those 
running  vertically  should  look  as  black  and  clearly  defined  as 
those  which  run  horizontally,  and  vice  versa.  If,  however, 
there  is  any  difference  between  them  as  to  shade  of  color  or 
distinctness  of  outline,  the  eye  is  astigmatic,  and  the  greater 
the  difference,  the  greater  the  degree.  Such  an  eye  as  this 
requires  peculiar  glasses,  which  can  only  be  determined  by  a 
careful  examination,  and  which  have  to  be  selected  to  fit  each 
case.  It  may  be  that  a  person  is  not  astigmatic  for  vertical  or 
horizontal  lines,  but  is  for  those  running  obliquely.  To  test 
this,  turn  the  drawing  so  that  what  are  ordinarily  the  vertical 
lines  shall  run  obliquely,  say,  at  an  angle  of  forty-five  de- 
grees. 

If,  now,  this  were  aU,  it  would  be  a  simple  matter  for  the 


360  THE  CRANIAL  NERVES. 

parent  or  teacher  to  determine  just  what  children  needed  a 
careful  examination,  but,  unfortunately,  there  are  a  large 
number  of  children  who,  as  has  been  already  explained,  have 
a  deficiency  of  optical  power,  but  who  can,  nevertheless,  neu- 
tralize this  deficiency  by  an  effort,  so  that  they  can  see  at  as 
great  a  distance  and  as  clearly  as  those  who  have  normal  eyes. 
These  are  those  who  most  suffer  from  headache,  and  from  all 
the  ills  of  a  nervous  nature  which  have  been  detailed  in  the 
foregoing  remarks.  The  only  satisfactory  way  out  of  the  dif- 
ficulty would  appear  to  be,  that  every  child  should  have  the 
optical  condition  of  the  eye  and  the  amount  of  vision  deter- 
mined, before  school  life  begins,  by  some  competent  person 
trained  in  the  methods  of  making  these  examinations. 

CHANGES  IN"  THE   PUPIL. 

The  pupil  of  the  eye  may  be  seen  to  dilate  when  distant 
objects  are  to  be  perceived,  and  to  contract  when  near  objects 
are  inspected,  since,  by  so  doing,  the  amount  of  light  which 
enters  the  eye  is  regulated,  and  the  distinctness  of  the  image 
is  thus  increased. 

Irritation  of  the  optic  nerve,  by  an  excessive  quantity  of 
light,  also  creates  contraction  of  the  pupil ;  while  the  same 
condition  may  be  the  result  of  simply  turning  the  eyeball 
inward.' 

In  the  early  stages  of  anaesthesia '  from  chloroform,  in 
alcoholic  excitement,  in  poisoning  from  morphia,  physostig- 
min,  and  some  other  drugs,  and,  finally,  in  deep  slumber,  the 
pupils  are  found  to  be  contracted. 

Dilatation  of  the  pupil  may  be  dependent  upon  a  dim 
light,  an  attempt  to  view  distant  objects,  emotional  excite- 
ment, the  latter  stages  of  anaesthesia  from  chloroform,  and 
from  belladonna  poisoning  and  that  of    drugs    of    similar 

action  ;  while  it  may  also  occur  in  all  conditions  creating  an 

• 

'  T  may  here  say  that  "  small  and  unequal  pupils  in  a  person  of  middle  age,  from 
twenty-five  to  sixty,  should  lead  to  an  inquiry  into  the  possible  existence  of  one  of  three 
morbid  states,  viz. :  paralytic  dementia  (or  general  paralysis),  sclerosis  of  the  posterior  col- 
umns, and  cardiac  or  aortic  disease  (intra-thoracic  disease)."     (E.  C.  Seguin.) 

*  Mich.  Foster,  "  Text-Book  of  Physiology." 


VISUAL  SENSATIONS.  3gl 

excess  of  aqueous  humor  within  the  eye,  and  during  dyspnoea 
and  excessive  muscular  exertion. 

The  mechanism  of  the  action  of  the  pupil  will  be  more 
properly  considered  under  the  description  of  the  third  nerve, 
which  furnishes  it  with  motor  power. 

VISUAL   SENSATIONS   AND   THEIR   MODIFICATIONS. 

Shadows  thrown  upon  the  retina  are  perceived  as  specks  in 
the  vision,  the  so-called  muscce  volitantes^  They  may  arise 
from  tears  upon  the  cornea,  a  temporary  unevenness  of  the 
cornea  after  the  eyelid  has  been  pressing  upon  it,  imperfec- 
tions of  the  lens  or  its  capsule,  and  from  shadows  produced 
by  the  margin  of  the  iris,  especially  if  it  be  imperfect. 

They  are  distinguished  chiefly  by  their  almost  continual 
change  in  position,  when  the  head  is  moved  up  and  down, 
and  by  a  tendency  to  entire  disappearance  when  an  effort  is 
made  to  fix  the  vision  upon  them. 

That  point  on  the  retina,  the  papilla,  where  the  optic  nerve 
pierces  it,  is  called  the  "blind  spot,"  since  no  sensations  of 
light  can  be  perceived  in  that  locality." 

In  that  portion  of  the  retina,  the  "macula  lutea,"  where 
the  images  to  be  perceived  by  the  optic  nerve  fall  most  direct- 
ly, and  where  most  of  our  visual  perceptions  are  therefore 
gained,  a  markedly  yellow  pigment  exists,  which  tends  to 
absorb  some  of  the  greenish-blue  rays  of  light ;  hence  what 
we  perceive  as  wJiite  in  color  is,  in  reality,  more  or  less  yellow. 

When  pressure  is  forcibly  exerted  upon  the  eyeball,  the 
whole  retina  speedily  becomes  insensible  to  light.  This  fact 
has  been  explained  as  the  result  of  a  loss  of  the  conductive 
power  of  the  nerve  structures.  Exner,''  however,  endeavors  to 
use  this  fact  as  the  basis  of  an  argument  to  prove  that  the 
sensation  of  light  is  the  result  of  some  substance  (as  yet  un- 
determined) within  the  retina,  whose  production  is  tempora- 
rily arrested  by  any  pressure  upon  the  eye  which  is  suffi- 
ciently forcible  to  occlude  the  vessels  of  the  retina,  and  thus 
to  interfere  with  its  nutrition. 

'  Bowman,  "  Phys.  Anat."  «  Helmholtz,  "  Phys.  Optik."  «  Op.  dt. 


362 


THE  CRANIAL  NERVES. 


THE   PERCEPTION'   OF   COLOR. 


The  subject  of  color  blindness^  which  is  to-day  assuming 
great  importance,  naturally  suggests  to  the  inquiring  mind — 
by  what  anatomical  arrangement  are  the  optic  nerve  libers 


Fia.  86. — Crystalline  lens,  antenor  view.    (Babuchin.) 

informed,  through  the  aid  of  the  coats  of  the  retina,  of  the 
perception  by  that  membrane  of  the  color  of  images  ? 

That  the  retinae  of  animals  possessed  color  was  first  noticed 
by  Krohn,  as  early  as  1839  ;  but  the  matter  was  not  regarded  as 
of  any  physiological  importance  until  Boll,  in  1876,  announced 
that  the  retina  of  all  vertebrated  animals  possessed  a  purplish 
color,  which  faded  in  the  light,  but  which  darkness  restored. 
He  concluded  that  the  color  must  be  largely  concerned  in  the 
act  of  vision.' 

The  subsequent  experiments  of  Kiihne  upon  this  subject 
seem  to  have  partially  verified  this  discovery,  but  exactly  what 

'  A  very  interesting  article,  by  my  friend  Dr.  Ayres,  of  this  city,  appeared  in  the  "  New 
York  Med.  Jour."  (December,  1880),  in  which  the  physiological  action  of  the  visual  purple 
was  discussed ;  its  function  is  here  stated  to  be  a  photo-chemical  07ie,  designed  to  accom- 
modate vinon  to  different  degrees  of  light,  since  it  is  capable  of  changing  and  regaining  its 
original  color  when  circumstances  demand  it  (an  intensity  of  light  or  an  approach  to 
darkness  causing  rapid  effects  upon  it). 


THE  VISUAL  PURPLE. 


363 


its  function  is  may  yet  be  considered  a  subject  of  investiga- 
tion. A  prominent  author  says  of  this  matter:  "It  is  very 
tempting  to  connect  this  visual  purple  with  color  vision ;  but 


Fig.  87.- 


-A.  Vertical  section  of  the  retina. 
(H.  Miiller.) 


Connection  of  the  rods  and  cones  of 
the  retina  with  the  nervotcs  elements. 
(Sappey.) 


A.  1,  1,  layer  of  rods  and  cones;  2,  rods;  3,  cones;  4,  4,  5,  6,  external  granule  layer; 

7,  inter-granule  layer  (cone-fiber  plexus);  8,  internal  granule  layer;  9,  10,  finely 
granular  gray  layer;  11,  layer  of  nerve  cells;  12,  12,  12,  12,  14,  14,  fibers  of  the 
optic  nerve  ;  13,  membrana  limitans. 

B.  1,  1,  2,  3,  rods  and  cones,  front  view;  4,  5,  6,  rods,  side  view;  7,  7,  8,  8,  cells  of 

the  external  and  internal  granule  layers ;  9,  cell,  connected  by  a  filament  with  sub- 
jacent cells;  10,  13,  nerve  cells,  connected  with  cells  of  the  granule  layers;  11,  21, 
filaments  connecting  cells  of  the  external  and  internal  granule  layers  (12  is  not  in 
the  figure);  14,  15,  16,  17,  18,  19,  20,  22,  23,  24,  25,  26,  a  rod  and  a  cone,  con- 
nected with  the  Cells  of  the  granule  layers,  with  the  nerve  cells,  and  with  the  nerve 
fibers. 


we  know  that  our  color  vision  is  most  exact  in  the  fovea  cen- 
tralis, where  the  retina  consists  of  cones  alone,  which  are  des- 
titute of  this  visual  purple." ' 

1  Mich.  Foster,  op.  cit. 


364  THE  CRANIAL  NERVES. 

While  no  positive  statements  can  as  yet  be  made  as  to  the 
function  of  that  layer  of  the  retina  known  as  ''the  rods  and 
cones  of  Jacob,"  still  authorities  seem  inclined  to  attribute  to 
the  cones,  rather  than  to  the  rods,  the  power  of  perceiving 
color.  It  is  known  that  these  cones  are  absent  in  the  retina 
of  nocturnal  animals  ;  while,  in  the  eyes  of  birds  and  reptiles, 
globules  containing  color  are  found  within  the  cones.  More- 
over, the  ''fovea  centralis"  in  the  human  eye  is  destitute  of 
rods. 

To  explain  our  perception  of  color,  the  hypothesis  was  first 
made  by  Young  that  there  existed  in  the  retina  the  power  of 
perceiving  three  distinct  color  sensations,  which,  being  parts 
of  the  spectrum,  could,  by  a  proper  admixture  of  certain  pro- 
portions of  each,  produce  white ;  he  further  supposed  that 
there  existed  three  distinct  sets  of  nerve  fibers,  each  set  being 
sensitive  to  a  primary  color  sensation,  viz.,  to  wave  lengths 
of  a  certain  length.  Helmholtz  has  done  much  to  bring  this 
theory  to  notice,  so  that  the  theory  is  known  now  as  the 
"  Young-Helmholtz  theory,"  rather  than  by  the  name  of  the 
originator  of  the  hypothesis  alone.  The  fact  that  the  most 
careful  microscopical  examinations  of  the  retina  fail  to  dis- 
cover the  existence  of  sets  of  fibers,  which  differ  in  their  ana- 
tomical construction,  seems  to  place  this  theory  rather  on  the 
basis  of  a  prelty  hypothesis  than  that  of  an  acknowledged 
fact. 

Hering  and  Aubert '  have  discarded  the  Young-Helmholtz 
theory,  however,  and  have  attempted  to  explain  the  percep- 
tion of  color  by  a  process  of  disintegration,  in  one  set  of 
colors,  and,  in  another,  by  a  process  of  assimilation  of  a 
property  of  the  retina,  which  is  denominated  '^ visual  sub- 
stance,^^ 

All  persons  vary  much  in  their  power  of  discriminating 
and  appreciating  color ; '  but  only  those  can  properly  be  said 
to  be  "color  blind  "who  regard  colors  as  similar  vdiich  to 
most  people  would  be  glaringly  distinct.     Thus,  red  and  green 

'  "  Physiologic  der  Netzhaut,"  1865. 

*  Seebeck,  Wartmann,  Miiller'a  "  Physiology  "  (Baly's  edition). 


COLOR  VISION. 


366  THE  CRANIAL  NERVES. 

are  commonly  mistaken  for  each  other;  while  purple  and 
blue,  red  and  brown,  and  brown  and  green,  are  often  detected 
from  one  another  with  difficulty,  if  at  all. ' 

APPARESTT   VISION   OF   OBJECTS   l^OT   REALLY   SEEN. 

Any  stimulation  of  the  optic  nerve  or  of  the  retina,  if  suffi- 
ciently intense,  may  give  rise  to  certain  sensations,  which  are 
mistaken  for  actual  vision.  As  examples  of  this  fact,  a  blow 
in  the  eye  or  on  the  back  of  the  skull  will  often  make  the 
injured  person  "  see  stars  "  or  have  flashes  of  light  apparently 
cross  the  field  of  vision. 

Foster '  mentions  a  case,  where,  by  a  voluntary  compres- 
sion of  the  eyeball  by  the  orbicularis  palpebrarum  muscle, 
gorgeous  visions  of  flowers  and  landscapes  could  be  produced. 

EFFECT   OF   OPTIC   NERVE   ON    COORDINATION. 

The  optic  nerve  may  become  a  means  of  vertigo,  when 
objects  are  caused  to  pass  rapidly  before  the  field  of  vision, 
as  in  viewing  a  waterfall,  being  rapidly  whirled,  etc.  This 
subject,  however,  will  be  more  fully  considered,  with  points 
of  interest  pertaining  to  the  auditory  nerve,  since  Meniere's 
malady  is  more  often  dependent  upon  disease  of  the  acoustic 
apparatus. 

Goltz '  has  shown,  by  experiments  upon  birds  whose  heads 
were  artificially  secured  in  an  abnormal  position,  that  they  at 
once  become  incapable  of  orderly  flight,  thus  further  confirm- 
ing the  apparent  connection  between  the  special  sense  of  sight 
and  those  muscular  movements  which  require  the  exercise  of 
the  power  of  coordination. 

EFFECT  OF  THE   OPTIC   NERVE   ON  THE   LACHRYMAL   APPARATUS. 

The  contraction  of  the  orbicularis  muscle  tends  to  press 
the  tears,  which  the  lachrymal  canals  contain,  onward  toward 
the  nasal  duct ;  and  they  dilate  to  receive  a  fresh  quantity 
during  the  relaxation  of  this  muscle.     Thus  the  act  of  winJc- 

'  Taylor's  «*  Scientific  Memoirs."  ■  Op.  cit. 

2  Pfliiger's  "  Archiv,"  1873,  as  quoted  by  Foster. 


NERVES  OF  LACHRYMAL  APPARATUS. 


367 


ing^  which  usually  precedes  any  special  attempt  to  see  with 
distinctness,  by  calling  the  orbicularis  palpebrarum  muscle 
into  play,  assists  in  cleansing  the  eye  of  any  excess  of  tears. 
It  has  been  stated  by  Demtschenko,'  that,  during  the  closure 
of  the  eyelid,  a  peculiar  arrangement  of  the  muscular  fibers 
tends  to  keep  the  lachrymal  canals  open,  and  thus  to  act  as 
an  aid  to  the  orbicularis  muscle  in  its  mechanical  effect.     In 


Fig.  89, — Lachrymal  and  Meibomian  glands.     (Sappey.) 

1,  1,  internal  wall  of  the  orbit  ;  2,  2,  internal  portion  of  the  orbicularis  palpebrarum  ;  3, 
3,  attachment  of  this  muscle  to  the  orbit ;  4,  orifice  for  the  passage  of  the  nasal 
artery ;  5,  muscle  of  Horner ;  6,  6,  posterior  surface  of  the  eyelids,  with  the  Meibo- 
mian glands  ;  7,  7,  8,  8,  9,  9,  10,  lachrymal  gland  and  ducts ;  11,  11,  openings  of  the 
lachrymal  ducts. 


addition  to  this  anatomical  device,  the  alternating  pressure 
of  the  tendo  oculi  upon  the  lachrymal  sac  tends  to  act  as  a 
pump,  and  thus  to  draw  the  tears  from  the  globe  of  the  eye.'' 
The  flow  of  tears,  while  constant  in  a  state  of  health,  may 
be  greatly  increased  by  a  reflex  act.  Such  exciting  causes  as 
a  stimulation  of  the  nasal  mucous  membrane,  the  conjunc- 
tiva, the  optic  nerve,  and  the  tongue,  and,  more  forcibly,  the 
effect  of  the  emotions,  are  commonly  perceived.  It  is  said 
that  venous  congestion  of  the  liead  is  frequently  manifested 
by  an  excessive  production  of  tears.'    The  different  efferent 

*  Hoffman  und  Schwald's  "  Bericht,"  1873. 

2  Darling  and  Ranney,  "  Essentials  of  Anatomy,"  1880. 

3  Mich.  Foster,  op.  cit. 


368 


THE  CRANIAL  NERVES. 


nerves,  which  exert  a  controlling  influence  upon  the  lachry- 
mal apparatus  in  response  to  the  exciting  causes  above  men- 
tioned, include  the  lachrymal  and  orbital  branches  of  the  fifth 
cranial  nerve  and  filaments  of  the  cervical  sympathetic' 

Many  of  the  facts  pertaining  to  the  optic  nerve  may,  by 
the  skillful  physician,  be  made  useful  in  his  daily  practice  as 
guides  to  diagnosis  ;  while  others  are  given  as  explanations 
of  many  phenomena  Avhich  often  occa- 
sion alarm  to  those  not  familiar  with  the 
;^    mechanism  of  their  production. 

CLINICAL   POINTS   AFFORDED   BY  MEANS  OF 
THE   OPTIC.  NERVE. 

The  optic  nerve  has  of  late  acquired 
an  importance  to  the  oculist,  w^hich  is 
based  upon  the  physiological  distribution 
of  the  nerve,  but  which  has  to  the  spe- 
cialist more  than  a  theoretical  value, 
since,  by  means  of  the  knowledge  af- 
forded, the  diagnosis  of  the  existence  of 
cranial  tumors  pressing  upon  the  nerve, 
or  of  local  pressure  from  inflammatory 
exudations^  may  be  not  only  positively 
made  out,  but  the  exact  situation  of  the 
pressure  often  determined. 

The  hypotheses  of  WoUaston  and 
Mayo  have  been  so  far  confirmed  by  later 
investigators,  that  it  may  now  be  quite 
positively  stated  that  an  exact  lateral  half  of  each  retina  de- 
rives its  power  of  vision  from  one  optic  tract,  and  the  other 
half  from  the  opposite  tract.  It  has  been  proven  that  the 
non-decussating  fibers  of  each  optic  tract  supj^ly  the  sense  of 
vision  to  the  outer  or  temporal  side  of  each  retina,  and  that 
the  decussating  fibers  of  each  optic  tract  supply  the  inner  or 
nasal  side  of  each  retina.  When,  therefore,  the  optic  tract 
of  either  side  is  pressed  upon,  so  as  to  affect  the  entire  thick- 


FiG.  90. — Lachrymal  ca- 
nals, lachrymal  sac, 
and  nasal  canal,  opened 
on  their  anterior  por- 
tion.    (Sappey.) 

1,  walls  of  the  lachrymal 
passages,  smooth  and 
adherent ;  2,  2,  walls 
of  the  lachrymal  sac, 
presenting  delicate 
folds  of  the  mucous 
membrane  ;  3,y  a  simi- 
lar fold  belonging  to 
the  nasal  mucous  mem- 
brane. 


'  See  experiments  of  Uerzenstein,  Wolfcrz,  Reich,  and  others. 


VARIETIES  OF  HEMIANOPSIA.  369 

ness  of  the  nerve,  and  thus  to  interfere  with  the  action  of  all 
the  fibers  which  that  tract  contains,  the  temporal  side  of  the 
retina  of  that  eye  w^hich  corresponds  to  the  optic  tract  affected 
and  the  nasal  side  of  the  retina  of  the  opposite  eye  will  be 
rendered  blind,  or  wall  be  impaired  in  exact  proportion  to  the 
pressure  exerted  upon  the  optic  tract.  Blindness  of  the  lat- 
eral half  of  the  retina  of  either  eye  is  termed  "hemiopia"  or 
"hemianopsia";  and  this  condition  may  affect,  1,  both  eyes 
similarly  ;  %  both  eyes  diametrically. 

When  either  eye  is  alone  affected  wdth  blindness,  it  indi- 
cates, as  a  rule,  that  the  optic  nerve  is  pressed  upon,  or  other- 
wise impaired,  at  a  point  situated  in  front  of  the  optic 
cJiiasm;  since,  if  the  optic  tract  were  the  seat  of  the  existing 
trouble,  both  eyes  would  be  affected,  as  it  would  be  almost 
impossible  for  the  pressure  to  affect  the  non-decussating 
fibers,  and  still  leave  the  decussating  fibers  of  the  tract  unin- 
jured, or  mce  versa.  With  this  as  a  starting-point  in  the 
diagnosis,  we  determine  which  half  of  the  eye  is  blind,  know- 
ing that,  if  the  nasal  side  be  the  one  where  vision  is  lost,  the 
pressure  must  be  on  the  inner  side  of  the  nerve,  and,  if  the 
outer  or  temporal  side  be  blind,  that  the  outer  side  of  the 
nerve  is  the  seat  of  the  disease  which  is  causing  the  pressure. 
Should  both  sides  of  one  eye  be  rendered  blind,  and  no  local 
cause  within  the  eye  be  found  to  exist,  then  the  existence 
of  pressure  anterior  to  the  optic  chiasm,  of  such  a  character 
that  the  entire  nerve  is  destroyed  or  impaired,  may  safely  be 
diagnosed. 

Total  blindness  of  one  eye  is  frequent  evidence  of  glioma 
or  sarcoma  within  the  orbit,  as  they  are  the  two  forms  of 
tumors  which  most  frequently  affect  that  region ;  and  the 
diagnosis  of  the  presence  of  this  cause  will  probably  be  con- 
firmed, in  case  it  exists,  by  symptoms  referable  to  paralysis  of 
some  of  the  muscles  of  the  eye,  since  the  same  pressure  will 
be  also  likely  to  affect  either  the  third,  fourth,  or  sixth  nerves. 

The  most  common  form  of  "hemianopsia"  '  met  with,  as 

^  A  synonym  for  hemiopia  in  its  generally  accepted  sense,  but  a  better  term,  since  it 
means  blindness  of  half  of  the  retina,  while  the  former  means  only  half  vision. 


370  THE  CRAmAL  NERVES. 

the  result  of  the  pressure  of  cranial  tumors,  is  where  the  tem- 
poral half  of  one  eye  and  the  nasal  half  of  the  opposite  eye 
are  rendered  blind.  This  clinical  fact  is  supported  by  the 
anatomical  distribution  of  the  fibers  of  the  optic  tract,  which, 
as  before  stated,  supply  the  temporal  half  of  the  eye  of  the 
same  side  and  the  nasal  half  of  the  eye  of  the  side  opposite. 
When  this  condition  is  met,  we  know  that  the  optic  tract,  or 
the  extension  of  its  fibers  backward  as  far  as  the  cerebral 
cortex  (Fig.  43),  must  be  involved  upon  the  side  corresponding 
to  the  eye  which  is  blind  in  its  temporal  or  outer  half  (Fig.  91). 

In  those  uncommon  cases  where  the  inner  or  nasal  half  of 
each  retina  is  deprived  of  sight,  the  existence  of  pressure  at 
the  anterior  or  posterior  portions  of  the  optic  chiasm  may  be 
diagnosed,  since  the  decussating  fibers  of  each  optic  tract 
cross  each  other  at  these  points  only ;  and  the  nasal  side  of 
each  eye  being  affected  proves  that  the  decussating  fibers  of 
each  tract  must  be  simultaneously  pressed  upon,  without  any 
disturbance  of  the  non-decussating  fibers. 

In  those  cases  where  the  outer  or  temporal  sides  of  both 
retinae  exhibit  evidences  of  pressure  from  some  cause  within 
the  cranium,  the  explanation  of  the  mechanism  of  its  produc- 
tion has,  until  of  late,  been  involved  in  obscurity ;  but  it  is 
now  explained  by  a  curious  anatomical  relation  between  the 
internal  carotid  arteries  (as  they  assist  to  form  *'the  circle  of 
Willis")  and  the  optic  nerve.'  It  will  be  observed,  by  refer- 
ence to  the  plates  of  your  anatomy,  that  the  anterior  commu- 
nicating artery  passes  underneath  the  optic  nerves  and  in 
front  of  the  chiasm,  while  the  main  trunks  of  the  carotid 
arteries  are  adjacent  to  the  chiasm,  and  curl  outward  from 
nearly  its  central  point  toward  its  outer  edge.  Now,  in  senile 
degeneration  of  the  vessels,  the  atheromatous  changes  in  the 
arterial  coats  tend  to  destroy  the  elasticity  of  the  vessels,  and 
to  either  shorten  them,  or  to  render  them  less  elastic,  and 
thus,  in .  this  region,  the  arteries  act  as  a  gathering-string 
around  the  optic  chiasm,  and,  by  pressing  upon  the  outer  por- 
tion of  each  tract,  the  non-decussating  fibers  of  each  tract  are 

'  An  explanation  original,  I  believe,  with  Professor  U.  Knapp,  of  this  city. 


CAUSES  OF  HEMIANOPSIA. 


371 


impaired,  while  tlie  decussating  fibers  of  each  tract  are  not 
injured,  thus  accounting  for  the  blindness  of  the  temporal 
half  of  each  retina. ' 


tm^k 


Fig.  91. — A,  Non-decussating  fibers  of  the  optic  tract  (colored  red  on  chart);  B,  Decus- 
sating fibers  of  optic  tract  (colored  blue  on  chart) ;  C,  Optic  Chiasm ;  D,  Retini 
,  (showing  nerve  distribution  to  each  half);  E,  Optic  Nerves;  F,  Optic  Tracts; 
a' — b',  region  where  pressure  may  produce  "hemianopsia"  or  "total  amaurosis"  of 
one  eye;  e' — d',  region  where  pressure  will  result  in  "hemianopsia"  of  opposite 
halves  of  the  retina  of  both  eyes ;  c' — c',  region  where  the  constriction  of  the  ves- 
sels of  the  "circle  of  Willis"  will  produce  "hemianopsia"  of  temporal  half  of  the 
retina  of  both  eyes;  b'  or  C,  special  localities  where  "hemianopsia"  of  the  nasal 
half  of  the  retina  of  both  eyes  will  ensue  from  pressure ;  C  c',  b  c',  region  which 
must  be  entirely  destroyed  by  pressure  to  produce  total  blindness  of  both  eyes. 

If  you  will  compare  Fig.  91  with  a  preceding  diagram 
(Fig.  43),  it  will  enable  you,  perhaps,  to  better  understand 
the  mechanical  explanations  of  the  various  conditions  which 
may  result  from  pressure  upon  the  optic  tracts,  or  upon  the 
optic  nerves,  if  in  front  of  the  chiasm.  You  will  perceive  that 
the  non- decussating  fibers  of  each  tract,  which  I  have  colored 
red,"  if  traced  to  their  distribution,  supply  the  outer  half  of 
the  eye  of  the  same  side,  while  the  decussating  fibers  of  each 
tract,  which  I  have  colored  blue,'  pass  to  the  inner  or  nasal 
side  of  the  opposite  eye.     You  can,  therefore,  see  the  reason 

'  It  might  be  possible  for  two  tumors,  each  so  situated  as  to  affect  the  outer  side  only 
of  each  optic  tract,  to  produce  this  condition ;  but  the  probability  of  such  a  condition 
ever  existing  in  any  special  case  would  be  extremely  small. 

^  Shaded  dark  in  figure,  but  colored  for  class  demonstration, 

3  Not  colored  in  plate,  but  represented  by  decussating  lines.  The  presence  of  color 
for  demonstration  to  large  classes  is  oftentimes  of  great  assistance. 


372  THE  CRANIAL  NERVES. 

for  the  following  summary  of  the  guides  afforded  by  partial 
blindness  of  the  retina,  in  making  a  diagnosis  of  the  situation 
of  cranial  tumors : 

1.  Total  hlindness  of  one  eye  indicates  pressure  between 
the  chiasm  and  the  eye  affected,  which  has  destroyed  the 
conducting  power  of  both  the  decussating  and  non-decussat- 
ing fibers  of  the  nerve. 

2.  Total  blindness  of  both  eyes  seldom  occurs  in  tumor ; ' 
but,  if  it  be  dependent  upon  a  tumor,  it  must  affect  the 
chiasm  itself,  and  have  completely  destroyed  it. 

8.  A  loss  of  vision  in  the  nasal  half  of  both  eyes  indicates 
the  existence  of  a  lesion,  either  in  front  of  or  behind  the  optic 
chiasm,  which  affects  only  the  decussating  fibers  of  each  tract. 
•  4.  A  loss  of  vision  in  the  nasal  half  of  one  eye  and  the  tem- 
poral half  of  the  other,  indicates  a  lesion  of  the  optic  tracts  or 
its  extension  backward  to  the  cerebral  cortex  (Fig.  43),  upon 
the  side  where  the  temporal  half  of  the  retina  is  destroyed, 
or  a  cortical  lesion  of  the  occipital  lobe  (probably  the  cuneus). 

5.  A  loss  of  vision  in  the  temporal  half  of  both  eyes  indi- 
cates senile  degeneration  of  the  vessels  forming  the  "circle  of 
Willis,"  which  are  creating  pressure  upon  the  outer  side  of 
each  of  the  optic  tracts. 

The  optic  nerve  may  be  the  guide  to  many  diseased  condi- 
tions of  parts  more  or  less  distant.  The  condition  of  hyper - 
cesthesia  of  the  retina  (to  which  membrane  its  terminal  fila- 
ments are  distributed)  may  be  indicative  of  congestive  diseases 
of  the  brain  ;  of  the  development  of  cerebral  tumors ;  and  of 
certain  mental  diseases  (as  prominently  shown  in  ecstasy, 
hypochondria,  etc.).  It  also  occurs  in  hysteria,  chorea,  chronic 
alcoholism,  narcotism,  the  inhalations  of  certain  toxic  gases, 
etc.  It  may  frequently  be  the  evidence  of  some  local  condi- 
tion of  the  optic  apparatus ;  hence  we  meet  it  in  cases  of 
congestive  and  inflammatory  conditions  of  the  retina ;  also 
where  an  excessive  amount  of  application  of  vision  has  been 
demanded,  in  disease  and  atrophy  of  the  nerve  itself,  and  in 
slight  compression  of  the  nerve  from  local  causes. 

'  This  condition  is  more  commonly  due  to  atrophy  of  the  optic  nerve  and  to  glaucoma. 


i 


AMBLYOPIA  AND  AMAUROSIS.  373 

When  the  optic  nerve  filaments  become  ancBstlietic^  sight 
is  impaired  in  the  exact  ratio  of  the  loss  of  sensibility  ;  hence 
we  speak  of  the  condition  of  '' amhlyopia^'^^  when  the  sight  is 
partly  destroyed  by  this  condition,  and  of  "amaurosis "  when 
the  sight  is  entirely  destroyed. 

We  may  consider  a  loss  of  sensibility  of  the  optic  nerve 
filaments  as  a  symptom  of  the  gravest  import,  since  it  indi- 
cates either  some  disease  of  the  brain  or  some  advanced 
changes  of  the  nerve  itself.  The  brain  conditions  which  are 
most  liable  to  produce  this  condition  are  as  follows :  nenro- 
retinitis,  which  may  follow  cerebral  haemorrhage,  cerebral 
softening,  Bright' s  disease,  lead  poisoning,  and  syphilis;  the 
various  forms  of  ataxia ;  cerebral  tumors ;  chronic  effusion 
into  the  ventricles  ;  and  hysterical  cerebral  disorders. 

The  local  conditions  which  may  result  in  optic  anaesthesia 
include  inflammation  of  the  retina  and  the  adjoining  struc- 
tures ;  haemorrhage  into  the  retina  ;  retinal  tumors  ;  the  com- 
pression of  glaucoma ;  pressure  of  tumors,  in  the  orbit  or 
cranium,  upon  the  optic  tracts ;  thickening  of  the  meninges 
in  the  vicinity  of  the  optic  chiasm  ;  and  traumatism. 

Atrophy  and  sclerosis  of  the  corpora  geniculata  may  result 
in  amaurosis';  lesions  of  the  cerebellum'  maybe  accompanied 
by  symptoms  referable  to  the  optic  apparatus  (probably  on 
account  of  the  pressure  created  upon  adjoining  regions  of  the 
encephalon) ;  and  an  increase  of  intra-cranial  pressure,  from 
any  cause,  may  produce  retinal  changes. 

THE  THIRD  OR  "MOTOR  OCULI "  NERVE. 

This  nerve  has  its  apparent  origin  from  the  inner  border  of 
the  cms  cerebri.  The  deep  origin  of  the  nerve  has  been  dis- 
cussed in  preceding  pages,  which  treat  of  the  crus  cerebri ; 
and  also  in  the  ijitroductory  pages  of  this  section,  to  which 
the  reader  is  referred. 

The  course  of  this  nerve,  after  it  escapes  from  the  brain, 
is  of  importance,  from  the  relations  which  it  has  with  impor- 

J  See  page  372  of  this  volume.  ^  ggg  page  235  of  this  volume. 


374 


THE  CRANIAL  NERVES. 


tant  structures,  and  from  the  physiological  phenomena  pro- 
duced by  it.  It  pierces  the  dura  mater  opposite  to  the  an- 
terior clinoid  process^  in  order 
to  reach  the  outer  wall  of  the 
cavernous  sinus,  where  it  lies 
in  close  relation  with  the  fourth 
cranial  nerve,  and  the  ophthal- 
mic branch  of  the  fifth  cranial 
nerve,  being  above  them  both, 
and  also  with  the  cavernous 
sinus,  which  lies  internal  to  it. 
It  is  in  this  region  that  the 
nerve  is  joined  by  filaments 
from  the  cavernous  plexus  of 
the  sympathetic  system. 

The  nerve  now  passes  from 
the  cavity  of,  the  cranium  by 
means  of  the  sphenoidal  fis- 
sure, having,  however,  divided 
into  two  branches,  before  its 
escape,  called  the  superior  and 
inferior. 

In  the  sphenoidal  fissure, 
these  two  branches  are  placed 
between  the  two  heads  of  the  external  rectus  muscle  of  the 
eyeball,  and  from  this  point  they  pass  onward  to  their  re- 
spective distributions,  viz.,  the  superior  branch  to  the  levator 
palpebrse  and  the  superior  rectus  muscles,  and  the  inferior 
branch  to  the  inferior  oblique,  the  inferior  rectus,  and  the  in- 
ternal rectus  muscles,  and,  by  a  small  filament,  furnishing  the 
motor  root  to  the  ciliary  or  lenticular  ganglion  of  the  orbit. 

The  third  cranial  nerve  thus  supplies  all  of  the  muscles  of 
the  eye  hut  two,  viz.,  the  superior  oblique  and  the  external 
rectus  muscles,  which  derive  their  motor  power,  respectively, 
from  the  fourth  and  the  sixth  nerves.  It  also  supplies 
filaments  to  the  ophthalmic  ganglion  (which  is  also  called 
the  ciliary,   and  the  lenticular   ganglion),   which  filaments 


Fia.  92.— DistribiUion  of  the  motor  oculi 
communis.     (Hirschfcld.) 

1,  trunk  of  the  motor  oculi  communis  ;  2, 
sicpcrior  branch;  3,  filaments  which 
this  branch  sends  to  the  superior  7'ectus 
and  the  levator  palpebri  superioris  ;  4, 
branch  to  the  internal  rectus  ;  5,  branch 
to  the  inferior  rectus  ;  6,  branch  to  the 
inferior  oblique  muscle ;  7,  branch  to 
the  lenticular  ganglion  ;  8,  motor  oculi 
externus;  9,  filaments  of  the  motor 
oculi  externus  anastomosing  with  the 
sympathetic ;  10,  ciliary  nerves. 


THE  MOTOR   OCULI  NERVE. 


375 


are  subsequently  distributed  to  tlie  ciliary  muscle  and  the 
iris. 

It  is  now  claimed  that  the  fibers  of  the  third  nerve,  which 
pass  to  the  aqueduct  of  Sylvius,  decussate ;  and  it  is  to  this 


K 


Fig.  93. —  Ciliary  muscle  ;  magnified  10  diameters.     (Sappey.) 

1,  1,  crystalline  lens;  2,  hyaloid  membrane;  3,  zone  of  Zinn ;  4,  iris;  5,  5,  one  of  the 
ciliary  processes ;  6,  6,  radiating  fibers  of  the  ciliary  muscle ;  V,  section  of  the  circu- 
lar portion  of  the  ciliary  muscle ;  8,  venous  plexus  of  the  ciliary  process  ;  9,  10, 
sclerotic  coat ;  11,  12,  cornea  ;  13,  epithelial  layer  of  the  cornea  ;  14,  membrane  of 
Descemet;  15,  ligamentum  iridis  peetinatum  ;  16,  epithelium  of  the  membrane  of 
Descemet;  lY,  union  of  the  sclerotic  coat  with  the  cornea  ;  18,  section  of  the  canal 
of  Schlemm. 

anatomical  arrangement  of  its  fibers  of  origin  that  the  effect  of 
the  pupil  of  one  eye  upon  the  condition  of  the  pu]3il  of  the 
opposite  eye  is  occasionally  observed  in  disease,  and  that  the 
muscles  of  the  two  eyes,  as  well  as  the  iris,  are  thus  enabled  to 
work  in  perfect  harmony  with  each  other.  As  an  example  of 
this,  it  is  occasionally  observed  that,  when  amaurosis  affects 
one  eye,  the  pupil  of  the  diseased  organ  will  not  respond  to 
the  effect  of  light  upon  the  retina  of  that  side,  but,  when  the 


376 


THE  CRANIAL  NERVES. 


light  creates  a  movement  of  the  iris  of  the  unimpaired  eye, 
the  pupil  of  the  opposite  side  also  responds,  thus  showing 
that  reflex  action  is  possible  between  the  two  eyes. 

MECHANISM   OF  THE   CONTRACTION-   OF  THE   PUPIL. 

The  mechanism  of  the  reflex  act,  by  which  the  third 
nerve  is  enabled  to  so  affect  the  contraction  of  the  pupil 
as  to  have  its  varying  size  correspond  exactly  to  the  re- 
quirements of  the  retina,  as  regards  the  amount  of  light 


Fig.  94. —  Choroid  coat  of  the  eye  and  the  ciliary  nerves.     (Sappey.) 

1,  optic  nerve ;  2,  2,  2,  2,  3,  3,  3,  4,  sclerotic  coat,  divided  and  tiu'sed  back  to  show  the 
choroid ;  5,  5,  5,  5,  the  cornea,  divided  into  four  portions  and  turned  back ;  6,  6, 
canal  of  Schlemm ;  7,  external  surface  of  the  choroid,  traversed  by  the  ciliary  nerves 
and  one  of  the  long  ciliary  arteries ;  8,  central  vessel  into  which  open  the  vasa  vorti- 
cosa ;  9,  9,  10, 10,  choroid  zone ;  11, 11,  ciliary  nerves;  12,  long  ciliary  artery ;  13,13, 
13,  13,  anterior  ciliary  arteries;  14,  iris;  15, 15,  vascular  circle  of  the  iris  ;  16,  pupil. 

necessary  for  perfect  vision  at  all  times  and  under  all  circum- 
stances, is  a  subject  of  interest  to  those  who  study  anatomy 
from  the  standpoint  of  its  physiological  bearings.  The  optic 
nerve,  when  a  person  comes  from  darkness  into  the  light, 
receives,  on  account  of  the  dilated  condition  of  the  pupil, 
an  excess  of  light  which  at  once  compels  the  eye  to  momen- 
tarily close*  until  th^  pupil  shall  become  contracted.     The 

*  A  reflex  act  produced  through  the  optic  nerve  upon  the  orbicularis  palpebrarum 
muscle. 


DISTRIBUTION  OF  THE  THIRD  NERVE. 


377 


sensation  of  over-stimulation  created  in  the  optic  nerve  by 
the  glare  of  light  entering  the  dilated  pupil  is  carried  back- 
ward to  the  brain,  and,  probably  in  the  region  of  the  aque- 
duct of  Sylvius,  creates  a  reflex  act  which  sends  motor  im- 
pulses along  the  fibers  of  the  third  nerve  to  the  iris,  by  means 
of  the  branch  to  the  ciliary  ganglion.  Thus  it  happens  that, 
when  the  eye  is  again  opened,  the  sensation  of  distress  in  the 
optic  nerve  is  no  longer  present,  and  the  pupil  is  found  to  be 
contracted  in  a  direct  proportion  to  the  amount  of  light  which 
at  the  time  exists. 

REASOI^S   FOR  THE   PECULIAR   DISTRIBUTION    OF   THE   THIRD   NERVE. 

The  distribution  of  the  third  cranial  nerve  may  suggest 
to  the  inquiring  mind  the  following  questions  :  "Why  does 


Fig.  95. — Plexus  of  ciliary  nerves. — Nerves  of  the  iris.     (After  Sappey.) 
A,  choroid ;  B,  iris  ;  1,1,1,1,  ciliary  nerves  dividing  at  their  terminal  extremity  into  two 
or  more  branches,  which  anastomose  to  form  a  circular  plexus  surrounding  the  greater 
circumference  of  the  iris ;  2,  2,  plexus  formed  by  this  anastomosis ;  3,  3,  nerves  of 
the  iris  originating  from  this  plexus. 

Nature  use  three  nerves  to  control  the  movements  of  the  six 
ocular  muscles,  when  she  could  have  used  one  nerve  to  accom- 
plish the  effects  Why  are  the  internal  rectus,  the  inferior 
oblique,  and  the  inferior  rectus  supplied  from  one  nerve 
source,  to  the  exclusion  of  the  external  rectus,  and  the  supe- 


378  *       THE  CRANIAL  NERVES. 

rior  oblique  muscles  ?  Furthermore,  why  is  the  iris  supplied 
with  nerve  power  from  the  third  nerve,  and  not  also  from  the 
fourth  nerve  or  the  sixth  nerve  ? " 

As  was  stated  in  the  introductory  lecture  of  this  course, 
when  touching  upon  the  distribution  of  nerves  in  general,  Na- 
ture often  indicates,  by  the  distribution  of  the  nerves,  some 
valuable  hints  as  to  the  physiology  of  the  parts  supplied 
by  each  nerve  filament ;  and  such  questions,  as  are  presup- 
posed above,  will,  if  constantly  asked  by  the  student  of  anat- 
omy, often  enable  him,  by  close  study,  to  gain  not  only 
information  of  a  most  practical  kind,  but  it  will  also  greatly 
assist  him  to  retain  in  his  memory  what  would  otherwise 
escape,  and  render  this  line  of  study  a  source  of  unceasing 
pleasure  and  interest. 

It  is  evident,  when  a  glance  at  the  distribution  of  the  mo- 
tor oculi  nerve  is  taken,  that  it  is  essentially  the  nerve  of 
accommodation  of  vision  for  objects  of  variable  distances 
from  the  retina.  By  its  control  over  the  internal  muscles  of 
the  orbit,  the  eyes  can  be  moved  in  unison  in  their  endeavor  f 
to  focus  objects  simultaneously  upon  each  retina,  and  thus  to  ] 
gain  a  perception  of  the  solidity  of  objects,  which  can  not  be  J 
aiforded  by  one  eye  alone.  It  is  a  fact,  which  perhaps  the  1 
reader  has  never  thought  of,  that  the  two  external  recti  mus-  1 
cles,  or  the  two  superior  oblique  muscles,  are  seldom  called  | 
into  simultaneous  action,  since  they  both  tend  to  cause  ^ 
the  eye  to  roll  outward,  and  thus  oppose  the  natural  move-  i 
ment  of  the  two  eyes,  one  of  which  usually  moves  inward  i 
while  the  other  moves  outward,  in  order  to  favor  the  percep-  \ 
tion  of  the  same  objects  by  the  retina  of  each  eye.  For  this  ; 
reason  alone,  it  would  be  impossible  that  these  two  muscles  j 
of  each  orbit  should  be  supplied  from  the  same  nerve  as  j 
the  other  muscles,  since  they  could  not  possibly  act  in  har-  ; 
mony  with  each  other.  Again,  the  superior  oblique  and  the  j 
external  rectus  muscles  are  seldom  called  into  simultaneous  .! 
action  except  in  oblique  movements  of  the  eye,  and  their  ' 
actions  are  so  dissimilar  that  they  have  often  to  act  both  with  ,^ 
and  without  the  aid  of  the  other;  hence   two   nerves  (the    \ 


ACCOMMODATION-  OF  VI SI  OR. 


379 


fourth  and  sixth)  are  furnished  so  that  each  muscle  can 
have  its  own  source  of  nerve  supply. 

The  distribution  of  the  third  nerve  to  the  iris  affords  a  still 
more  beautiful  example  of  the  con- 
stant efforts  of  Nature  to  bring  all 
parts  into  a  harmony  with  each  oth- 
er, and  by  the  simplest  means  at 
her  control.  It  has  been  mentioned, 
in  connection  with  the  optic  nerve, 
that  the  pupil  contracts  as  the  eye 
is  drawn  inward,  and  also  in  at- 
tempts to  focus  near  objects  upon 
the  retina.  Now,  the  third  nerve 
is  the  nerve  by  which  not  only  is 
the  eye  drawn  inward,  but  it  is 
also  the  nerve  by  which  the  ciliary 
muscle  of  the  eye  is  enabled  to 
affect  the  convexity  of  the  crystal- 
line lens  of  the  eye,  and  thus  to 
act  as  an  adjuster  of  the  focal  dis- 
tance of  objects  whose  images  fall 
upon  the  retina.     How  important 

it  is,  therefore,  that  the  pupil  which  is  so  essential  to  the 
proper  performance  of  vision,  since  it  controls  the  quantity 
of  light  admitted  to  the  retina,  should  be  placed  under  the 
same  nervous  control  as  the  muscles  of  accommodation  of 
vision  ! 

MECHA]S"ISM   OF  THE   DILATATION   OF  THE   PUPIL. 

The  pupil  is  made  to  dilate  by  means  of  muscular  fibers, 
which  radiate  from  the  margin  of  the  pupil  toward  the  cir- 
cumference of  the  iris.  It  is  probable  that  these  fibers  are 
under  the  control  of  the  sympathetic  system  of  nerves.'  If 
so,  it  must  be  observed  that  the  sympathetic  nerves  have 
an  effect  upon  the  iris  directly  opposite  to  that  which  it 
exercises  upon  the  blood-vessels,   since,  when  it  is  stimu- 

*  Experiments  of  Julius  Budge,  1851,  and  Augustus  Waller,  "  Gazette  Medicale  de 
Paris."    Discovered  by  Petit,  1827. 


Fig.    96. — Ciliary    nerves^     course 
and  termination.   (After  Sappey.) 

1,  optic  nerve,  covered  by  its  exter- 
nal or  ligamentous  envelope; 
2,  optic  nerve,  covered  only  by 
its  proper  envelope  (neurilemr 
ma);  3,  3,  sclerotic,  or  fibrous 
envelope  of  the  eyeball :  4,  4, 
iris ;  5,  pupil ;  6,  6,  ciliary 
nerves  penetrating  the  scle- 
rotic ;  7,  7,  nerves  passing  be- 
tween sclerotic  and  choroid  ;  8, 
8,  plexus  resulting  from  their 
anastomoses  ;  9,  9,  ramifications 
extending  from  this  plexus  into 
the  iris. 


380 


THE  CRANIAL  NERVES. 


lated,  tlie  pupils  are  dilated,  while  the  blood-vessels  are  con- 
tracted. 

Mosso '  has  endeavored  to  show  a  relation  between  the  tur- 
gescence  of  the  vessels  of  the  iris  and  the  extent  of  dilatation 
of  the  pupil  which  exists  at  the  same  time,  and  thus  to  avoid 


Fig.  97. — Section  of  tJie  lens,  etc.,  shoinng  the  mechanism  of  accommodation.    (Fick.) 

The  left  side  of  the  figure  {F)  shows  the  lens  adapted  to  vision  at  infinite  distances  ;  the 
right  side  of  the  figure  {N)  shows  the  lens  adapted  to  the  vision  of  near  objects,  the 
ciliary  muscle  being  contracted  and  the  suspensory  ligament  of  the  lens  consequently 
relaxed. 


the  apparent  inconsistency  in  the  effect  of  the  sympathetic 
system  upon  the  same  type  of  muscular  structure. 

Oehl "  and  others  claim  that  the  sympathetic  fibers,  which 
act  in  antagonism  to  those  of  the  third  nerve  upon  the  iris, 
are  not  derived  from  the  ophthalmic  ganglion,  but  accompany 
the  ophthalmic  branch  of  the  fifth  cranial  nerve,  and  enter  the 
eye  with  the  long  ciliary  nerves  ;  and  that,  when  these  sympa- 
thetic filaments  are  divided,  stimulation  of  the  main  sympa- 
thetic cords  no  longer  causes  dilatation  of  the  pupil.  He  thus 
ascribes  to  the  fifth  cranial  nerve  the  power  of  dilating  the 
pupil,  and  regards  the  Gasserian  ganglion  as  the  source  from 
which  this  power  is  derived  from  the  sympathetic  system. 

The  experiments  of  Oehl  were  made  upon  dogs  and  rabbits, 
and  have  been  confirmed  by  Rosenthal,  Hensen,  Yolckers, 
and  Yulpian.  The  effect  of  these  fibers  of  the  fifth  nerve  is 
thought  by  these  observers  to  be  dependent  upon  a  vaso- 
motorial  influence  upon  the  blood  supply  of  the  iris. 


»  Cf.  Mosso,  Turin,  1876. 


»  Hcnle  und  Meissner's  "Bericht,"  1862. 


THE  MOVEMENTS  OF  THE  EYEBALL.  381 

Slight  oscillations  of  the  pupil  may  be  observed  to  occur 
synchronously  with  the  action  of  the  heart,  and  others,  also, 
with  the  respiratory  movements.  These  oscillations  have  been 
by  some  considered  as  an  evidence  that  the  movements  of  the 
pupil  were  the  result  of  alterations  in  its  vascularity,  the  iris 
contracting  when  its  vessels  are  filled,  and  dilating  when  its 
vessels  are  empty ;  but  the  physiological  fact  that  the  move- 
ments of  contraction  and  dilatation  of  the  pupil  are  noticed  in 
the  bloodless  eye  seems  to  point  to  some  other  agency  than 
simply  an  alteration  in  the  blood  supply/ 

MOTIONS   OF  THE   EYEBALL. 

Since  the  third  nerve  is  distributed  to  all  of  the  muscles 
of  the  eyeball  but  two,  the  motions  of  the  eye  are  largely 
controlled  by  it ;  while  accommodation  of  msion  is  also  pro- 
duced by  its  distribution  to  the  ciliary  muscle.  Some  prac- 
tical facts  may  be  here  noted  respecting  the  movements  of 
the  eyeball,  which  have  not  only  a  general  interest,  but  a 
diagnostic  value. 

The  eye  is  virtually  a  ball  placed  in  a  socket,  the  orbit 

'  "  The  impairment  of  iritic  reflex  action  ('  pupillary  reflex ')  was  first  intelligently 
studied  in  1869,  by  Dr.  Argyll  Robertson,  of  Edinburgh.  His  observations  have  since 
been  abundantly  verified  by  numerous  observers,  and  an  exhaustive  paper  on  the  subject 
has  been  published  by  Professor  W.  Erb,  of  Leipsic,  in  the  '  Archives  of  Medicine,'  Oc- 
tober, 1880.  Robertson,  and  others  after  him,  noticed  that  the  pupils  of  tabetic  patients 
did  not  dilate  in  the  shadow  and  contract  in  the  light,  as  do  normal  pupils,  and  they  fur- 
ther observed  that  during  the  effort  of  accommodation  there  occurred  a  normal  pupillary 
contraction.  In  other  words,  the  reflex  iris  movements  were  abolished,  while  its  associa- 
ted quasi-voluntary  movements  were  preserved.  These  phenomena  may  be  observed  in 
almost  all  patients  suffering  from  posterior  spinal  sclerosis,  and  I  am  in  the  habit  of  call- 
ing the  attention  of  students  to  the  symptom.  In  two  of  the  patients  now  under  my  care 
this  condition  is  not  present,  but  there  have  been  cases  of  abnormal  sclerosis  in  which  all 
the  symptoms  appeared  in  a  most  irregular  manner."    (E.  C.  Seguin,  "  Med.  Record,"  1881.) 

"  The  pupils  in  a  suspected  case  of  posterior-spinal  sclerosis  are  to  be  tested  in  the  fol- 
lowing manner :  the  patient  is  placed,  seated  or  standing,  facing  a  brightly  illuminated 
window,  and  told  to  keep  his  look  fixed  on  some  distant  object,  such  as  a  house  or  tree. 
By  alternately  closing  and  opening  the  lids,  or,  better,  by  shading  the  eyes  with  one's 
hand  momentarily,  it  is  easy  to  see  if  the  pupils  change  diameter.  It  is  of  the  utmost 
importance  that  the  patient's  intelligent  assistance  be  secured,  in  order  that  his  gaze  shall 
remain  adjusted  for  distance.  In  a  given  case  the  absence  of  reaction  to  light  having 
been  noted,  we  next  hold  up  one  finger  or  a  small  object  within  a  foot  of  the  patient's 
face,  and  bid  him  look  at  it.  At  once  the  pupils  contract,  and  do  so  in  proportion  to  the 
accommodative  effort  and  the  coincident  convergence.  When  the  patient  looks  at  the  dis- 
tant object,  and  relatively  or  absolutely  relaxes  his  accommodation,  the  pupils  dilate  again." 
27 


382 


THE  CRANIAL  NERVES. 


and  the  globe  forming  a  ball-and-socket  joint.  In  its  socket 
joint,  the  eye  is  capable  of  a  variety  of  movements  ;  but  it  can 
not,  by  any  voluntary  effort,  be  moved  out  of  its  socket.  By 
disease,  however,  the  position  of  the  eyeball  within  the  cavity 


Fig.  98. — Muscles  of  the  eyeball.     (Sappey.) 

1,  attachment  of  the  tendon  connected  with  the  inferior  rectus,  internal  rectus,  and  ex- 
ternal rectus ;  '2,  external  rectus,  divided  and  turned  downward  to  expose  the  inferior 
rectus ;  3,  internal  rectus ;  4,  inferior  rectus ;  5,  superior  rectus ;  6,  superior  oblique ; 
7,  pulley  and  reflected  portion  of  the  superior  oblique ;  8,  inferior  oblique ;  9,  levator 
palpebrae  superiorls ;  10, 10,  middle  portion  of  the  levator  palpebrae  superioris ;  11,  op- 
tic nerve. 


of  the  orbit  may  be  materially  altered.  By  pressure  on  the 
nerves  distributed  to  its  muscles,  paralysis  of  those  individual 
muscles  may  result  which  are  supplied  by  the  affected  nerve, 
and  the  eye  may  thus  be  deflected  from  its  normal  position 
by  the  other  muscles,  whose  motor  power  is  unimpaired.  The 
anatomical  fact,  that  the  muscles  which  move  the  eyeball  de- 
rive their  motor  power  from  three  sources,  viz.  :  the  third, 
fourth,  and  sixth  cranial  nerves,  may  often  be  made  a  means 
of  determining  the  situation  of  abnormal  conditions  within 
the  orbit  or  cranial  cavity,  by  a  thorough  familiarity  with  the 
points  of  origin  of  each  of  these  nerves,  and  the  relations 
which  each  bears  to  the  surrounding  parts  throughout  the 
whole  length  of  its  course. 


THE  MOVEMENTS   OF  THE  EYEBALL. 


383 


It  has  been  shown  by  Bonders  that,  though  we  can  move 
the  eye  in  almost  every  possible  variety  of  inclination,  we  can 
not,  by  a  voluntary  effort,  rotate  the  eyeball  around  its  longi- 
tudinal visual  axis.  The  arrangement  of  the  muscles  of  the 
eyeball  would  seem  to  permit  of  such  a  movement,  but  we 
can  not  by  any  direct  effort  of  will  bring  it  about  by  itself, 
although  we  can  occasionally  produce  it  unconsciously  when 
we  endeavor  to  move  the  eyeballs  in  certain  special  directions. 

During  movements  of  the  head,  the  eyes,  if  directed  toward 
an  object,  may  be  kept  stationary  upon  that  object,  in  spite  of 
such  movements  of  the  head, '  very  much  as  the  needle  of  the 
ship's  compass  remains  stationary  when  the  ship  is  turned. 
By  this  wonderful  coordination  of  movement  steadiness  of 
msion  is  insured,  which  would  be  otherwise  impossible.'' 


A  TABLE   SHOWING   THE   ACTION^   OF  THE   OCULAR  MUSCLES. 

To  elemte  the  eye \  ^^f "«  «"P^"^^- 

(  Obliquus  inferior. 

To  depress  the  eye \  Rectus  inferior. 

To  adduct  toward  the  nasal  side. . 
To  addiLct  toward  the  malar  side. 


Straight  movements. 


Oblique  movements. 


Obliqnns  superior. 
Rectus  internus. 
Rectus  externus. 

c  Rectus  superior. 
To  elevate  and  adduct  the  eye )  Rectus  internus. 

(  Obliquus  inferior. 

c  Rectus  inferior. 
To  depress  and  adduct  the  eye )  Rectus  internus. 

(  Obliquus  superior. 

r  Rectus  superior. 
To  elevate  and  abduct  the  eye }  Rectus  externus. 

'  Obliquus  inferior. 

r  Rectus  inferior. 
To  depress  and  abduct  the  eye )  Rectus  externus. 

(  Obliquus  superior. 

In  the  accompanying  table,"  in  which  the  various  motions 
of  the  eye  are  enumerated,  and  the  combinations  of  muscles 
necessary  to  produce  each  of  these  individual  motions  are 
shown,  it  will  be  perceived  that  in  the  straigM  deflections  of 

*  An  effect  due  chiefly  to  the  action  of  the  oblique  muscles  of  the  eye. 
^  Mich.  Foster,  "  Text-Book  of  Physiology." 
3  After  Mich.  Foster,  op.  eit. 


384  THE  CRANIAL  NERVES. 

the  globe  of  the  eye  never  more  than  two  muscles  are  required 
to  produce  them,  and  often  only  one ;  while,  in  the  oblique 
deflections  of  the  globe,  three  muscles  are  always  compelled 
to  work  in  unison.  It  may  furthermore  be  stated  that,  to 
counterbalance  the  action  of  either  of  the  oblique  muscles  of 
the  eye,  tw^o  muscles  are  always  required.  Suppose,  for  ex- 
ample, that  the  superior  oblique  muscle  of  the  orbit  was  para- 
lyzed from  pressure  upon  the  fourth  nerve,  the  eye  would 
then  be  drawn  downward  and  outward  only  by  the  combined 
action  of  the  external  and  inferior  recti  muscles,  although 
that  is  the  direct  line  of  action  of  the  muscle  paralyzed ;  while, 
if  that  muscle  should  contract,  and  thus  displace  the  eye 
downward  and  outward,  the  antagonistic  muscles  would  be 
the  superior  and  internal  recti  muscles,  since  the  former 
would  tend  to  draw  the  eye  upward  and  inward,  while  the 
latter  would  also  assist  in  drawing  the  eye  inward. 

The  ability  to  move  either  of  the  eyes  independently  of  the 
other  is  possessed  by  very  few  individuals,  although,  in  rare 
cases,  such  a  power  is  present.  The  movements  of  the  eye 
have  been  so  arranged  by  Nature  that  the  objects  seen  shall 
affect  the  corresponding  portions  of  each  of  the  two  retinae,  in 
order  to  insure  single  vision ;  and,  for  that  reason,  the  two 
eyes  will  be  perceived  to  move  exactly  alike,  each  passing 
simultaneously  to  the  left  or  to  the  right,  upward  or  down- 
ward. 

It  is  evident,  therefore,  when  we  throw  into  action  the 
rectus  intemus  of  one  eye,  that  we  use  the  rectus  externus  of 
the  opposite  eye,  and  vice  versa,  in  case  the  object  to  be  fo- 
cused upon  the  retinae  lies  away  from  the  median  line  of  the 
head  ;  but,  if  it  lies  in  the  direct  line  of  vision,  but  so  close  to 
the  face  as  to  require  a  muscular  effort  to  focus  it  upon  the 
retinae,  then  the  two  internal  recti  muscles  are  called  into 
simultaneous  action.  Finally,  in  case  the  object  to  be  per- 
ceived lies  at  a  distance  from  the  eyes,  it  becomes  necessary 
for  the  eyes  to  be  brought  into  nearly  a  condition  of  parallel- 
ism^  to  accomplish  which  the  two  external  recti  muscles  are 
called  into  simultaneous  action. 


CENTER  FOR   OCULAR  MOVEMENTS. 


385 


Sucli  a  complex  coordination  of  movement  as  the  various 
positions  of  the  eyes  demand  would  seem  to  indicate  that  a 
special  arrangement  had  been  made  within  the  component 
parts  of  the  brain  to  provide  for  its  control,  and  thus  insure 


rJnf> 


r.ext. 


T-sup.  r.ini 
r.inf. 


Fig.  99. — Diagram  showing  the  axes  of  rotation  of  the  eyeball.     (After  Tick.) 

The  black  lines  indicate  the  direction  of  the  power  applied  by  each  of  the  six  ocular  mus- 
cles. The  dotted  lines  indicate  the  axis  of  rotation  of  the  eyeball.  The  axis  of  rota- 
tion for  the  rectus  externus  and  rectus  internus  muscles,  being  perpendicular  to  the 
page,  can  not  be  shown  in  the  diagram. 


that  harmony  which  is  absolutely  required.  The  experiments 
of  Adamiik  ^  tend  to  designate  the  tubercula  quadrigemina  as 
provided  with  distinct  centers,  which  control  certain  move- 
ments of  the  eyes.  Thus,  he  finds  in  the  nates  (the  upper 
portion  of  the  tubercula  quadrigemina)  a  common  center ""  for 
both  eyes,  stimulation  of  the  right  side  producing  movements 
of  both  eyes  to  the  left,  of  the  left  side,  movements  to  the 
right ;  while  stimulation  of  the  middle  line,  behind,  causes  a 

^  Quoted  by  Flint,  Foster,  and  others. 

"^  For  details  concerning  subdivisions  of  the  nuclei  of  origin  of  the  third  nerve,  con- 
sult a  previous  page  of  this  volume. 


386  TEE  CRANIAL  NERVES. 

downward  movement  of  both  eyes,  with  a  convergence  of  the 
axes,  and,  if  made  in  front,  an  upward  movement  with  a  return 
to  parallelism,  both  of  which  effects  are  accompanied  by  the 
movements  of  the  pupil  naturally  associated  with  them. 

The  third  nerve  has  a  decided  importance  in  affording  us 
one  means  of  determining  the  distance  of  objects  from  the 
retinae  which  perceive  them,  viz.,  the  muscular  sense.  It  has 
been  previously  stated  that,  in  order  to  perceive  near  objects, 
the  internal  recti  and  the  ciliary  muscles  of  either  eye  are 
called  into  simultaneous  action,  and  we  soon  learn  to  uncon- 
sciously estimate  the  amount  of  muscular  j)ower  required  to 
properly  adjust  the  eye  for  distinct  vision,  and  thus  to  use 
the  third  nerve,  as  well  as  the  optic  nerve,  as  a  guide  to  the  ac- 
curate determination  of  distance. 

ALTERATION   OF  THE   POSITION   OF  THE  HEAD   FROM   PARALYSIS   OF 
THE  OCULAR  MUSCLES. 

It  is  a  fact  well  known  among  oculists,  and  one  which 
often  helps  them  materially  in  diagnosis,  that  the  defects 
of  vision,  occasioned  by  impairment  in  the  power  of  some  of 
the  muscles,  which  control  the  eyeball,  cause  the  patients  un- 
consciously to  assume  a  position  of  the  head  which  tends  to 
assist  them  in  the  use  of  the  affected  eye.  So  diagnostic  are 
some  of  the  attitudes  assumed  by  this  class  of  afflicted  people, 
that  the  condition  which  exists  may  be  told  at  a  glance,  as 
the  patient  enters  a  room,  by  one  thoroughly  familiar  with 
the  diseases  of  this  important  organ.  The  explanation  of  this 
tendency,  on  the  part  of  this  class  of  patients,  lies  in  the  fact 
that  any  loss  of  power  in  the  ocular  muscles  immediately 
shows  itself  in  the  perception  of  every  object,  as  it  were, 
doubled;  and  it  is  to  overcome  these  double  images  that 
patients  almost  instantaneously  discover  their  ability  to  get 
rid  of  the  annoyance  by  some  special  attitude,  which,  of 
course,  depends  upon  the  muscle  which  is  weakened  or  para- 
lyzed. 

It  will  be  necessary,  in  order  to  make  you  clearly  under- 
stand the  mechanism  of  this  peculiarity,  that  the  separate 


ABNORMAL  ATTITUDE  FROM  OCULAR  PARESIS.        387 

action  of  the  six  muscles  whicli  directly  act  upon  the  globe  of 
the  eye  be  considered. 

The  action  of  each  of  the  ocular  muscles  may  be  given, 
then,  as  follows,  with  the  proviso  that  many  of  the  motions 
of  the  eye  are  not  the  result  of  the  contraction  of  any  single 
muscle,  but  often  of  a  number  acting  either  in  unison  or  suc- 
cessively. 

The  superior  oblique  muscle  turns  the  eye  downward  and 
outward. 

The  inferior  oblique  muscle  turns  the  eye  upward  and 
outward. 

The  superior  rectus  muscle  turns  the  eye  upward  and 
inward. 

The  inferior  rectus  muscle  turns  the  eye  downward  and 
inward. 

The  internal  rectus  muscle  turns  the  eye  directly  inward. 

The  external  rectus  muscle  turns  the  eye  directly  outward. 

This  statement  as  to  the  above  muscles  reveals  nothing 
which  would  not  be  immediately  suggested  by  the  insertion 
of  each,  with  the  exception  of  the  superior  and  inferior  recti 
muscles,  which,  besides  the  action  which  their  situation 
would  naturally  suggest,  tend  also  to  draw  the  eyeball  in- 
ward, on  account  of  the  obliquity  of  the  axis  of  the  orbit  and 
the  same  obliquity  of  the  muscles,  since  they  arise  at  the  apex 
of  the  orbit.  The  action  of  the  oblique  muscles  is,  as  any  one 
familiar  with  their  origin  and  insertion  would  naturally  sur- 
mise, to  control  the  oblique  movements  of  the  eyeball. 

Now,  as  soon  as  any  one  of  these  six  muscles  becomes 
pressed  upon  and  weakened  by  the  presence  of  tumors,  in- 
flammatory exudation,  syphilis,  or  other  causes,  the  patient 
at  once  perceives  double  images,  and,  in  order  to  get  his  eye 
into  such  a  relative  position  with  that  of  the  healthy  side  as 
to  enable  them  both  to  focus  upon  the  same  object  in  a  natu- 
ral manner,  the  patient  soon  learns  to  so  move  his  head  as  to 
compel  the  two  eyes  to  look  in  parallel  directions. 

A  very  simple  rule  can  be  suggested  by  which  you  may  be 
enabled,  not  only  to  tell  in  what  direction  a  patient  would  move 


388  THE  CRANIAL  NERVES. 

his  head  in  case  any  special  muscle  be  rendered  weak  or  utter- 
ly useless,  but  also  to  diagnose  the  muscle  affected,  when  you 
look  at  the  patient,  without  any  knowledge  of  his  history. 
The  rule  may  be  thus  stated :  In  paresis  of  any  of  the  ocu- 
lar muscles^  the  head  is  so  deflected  from  its  normal  posi- 
tion that  the  chin  is  carried  in  a  direction  corresponding  to 
the  action  of  the  affected  muscle. 

Thus,  in  paresis  of  the  external  rectus,*  the  chin  would  be 
carried  outward  toward  the  injured  muscle ;  while,  in  paresis 
of  the  internal  rectus  muscle,  the  head  would  be  turned  away 
from  the  side  on  which  the  muscle  fails  to  act.  In  case  the 
superior  oblique  muscle  is  impaired,  the  chin  would  be  carried 
downward  and  outward ;  while,  in  the  case  of  the  inferior 
oblique  muscle,  the  chin  would  have  to  be  moved  upward 
and  outward  to  benefit  the  vision  of  the  patient.  The  supe- 
rior and  inferior  recti  muscles,  when  impaired  by  disease  or 
other  causes,  would  likewise  create  a  deflection  of  the  head  in 
a  line  corresponding  to  that  of  their  respective  actions. 

CLINICAL   POINTS   OF   INTEREST   PERTAINING   TO   THE  THIRD   NERVE. 

Paresis  of  the  external  and  internal  recti  muscles  causes,  in 
addition  to  the  facts  already  described,  another  point  of  very 
great  value  in  diagnosis,  viz.,  an  alteration  in  the  apparent 
size  of  the  objects  seen  from  what  they  would  be  in  health. 
The  condition  of  vision,  termed  by  oculists  " megalopsia''''  or 
^^ macropsia^^^  signifies  paresis  of  the  external  rectus;  while 
the  opposite  condition,  called  ''m/crop^m,"  indicates  loss  of 
power  in  the  internal  rectus  muscle. 

In  the  former  of  these  conditions,  the  objects  seen  by  the 
patient  seem  to  be  greater  in  point  of  size  than  the  intelligence 
of  the  patient  assures  him  is  the  case ;  while,  in  the  latter, 
objects  seem  smaller  to  the  patient  than  they  really  are. 

To  explain  to  you  just  how  these  variations  of  vision  are 

•  While  this  statement  would  be  absolutely  true  in  theory  in  all  cases,  we  must 
acknowledge,  as  a  clinical  fact,  that  patients  learn  to  utterly  dinregavd  the  image  in  the 
aifected  eye,  when  the  internal  or  external  rectus  is  the  seat  of  paresis,  and  to  use  the  nor- 
mal eye  only  for  the  purposes  of  vision,  thus  rendering  this  attitude  of  the  head  less  diag- 
nostic than  when  the  oblique  muscles  are  affected. 


MEGALOPSIA  AND  MICROPSIA.  389 

accomplislied  may  require  a  more  extended  discussion  of  tlie 
physiological  problems  of  vision  than  an  anatomical  discus- 
sion can  properly  deal  with  ;  but,  to  understand  it,  you  must 
know  that  the  apparent  size  of  any  object  depends  upon 
the  ability  of  the  person  to  properly  and  accurately  appreci- 
ate the  angle  formed  between  rays  of  light  coming  from  the 
object  and  entering  the  pupils  of  each  eye,  or,  in  other  words, 
the  distance  at  which  the  object  is  placed  from  the  retina. 
Now,  in  the  case  of  paresis  of  the  external  rectus  muscle,  the 
object  is  caused  to  appear  nearer  to  the  eye  than  it  really  is, 
and  thus  to  be  larger  than  normal  vision  would  cause  it  to 
seem,  since  the  angle  of  the  axes  of  vision  is  greater  ;  while, 
in  case  of  the  paralysis  of  the  internal  oblique,  the  object  is 
apparently  much  farther  removed  from  the  eye  than  it  really 
is,  and  thus  the  intelligence  construes  it  as  of  smaller  size  than 
it  would  if  the  visual  perceptions  were  normal. 

There  is  only  one  other  condition  of  the  eye  where  the  size 
of  objects  perceived  by  the  retina  is  either  increased  or  mark- 
edly diminished,  if  the  actual  size  be  taken  as  a  standard  of 
measurement,  and  this  condition  is  one  of  inflammation  of  the 
choroid  coat  of  the  eye.  It  is  a  well-recognized  fact  that,  in 
the  effusive  form  of  choroiditis,  objects  are  perceived  as  much 
smaller  than  they  really  are,  while  in  cicatricial  choroiditis 
the  size  of  the  object  is  magnified. 

These  phenomena  can  not  be  explained  as  the  result  of  a 
change  in  the  angle  of  the  axis  of  vision,  since  nothing  exists 
to  disturb  the  perception  of  distance  ;  but  it  is  attributed  to  a 
separation,  in  the  one  case,  and  to  an  aggregation  in  the 
other,  of  the  cones  of  the  retina. 

The  eye,  by  constant  use,  has  become  enabled  to  partly 
estimate  the  size  of  objects  by  the  number  of  cones  in  the 
retina  which  are  covered  by  the  image  of  the  object.  Thus, 
when,  from  causes  such  as  have  been  mentioned  above,  the 
elements  of  the  retina  are  either  huddled  more  closely  to- 
gether by  a  cicatrix  of  the  choroid  coat  of  the  eye,  or  dissem- 
inated over  a  larger  space  than  they  normally  occupy  by  an 
effusion  of  the  choroid  coat,  the  number  of  cones  covered  by 


390 


THE  CRANIAL  NERVES. 


the  image  thrown  upon  the  retina  is  either  increased,  thus 
apparently  magnifying  the  size  of  the  object,  or  the  number 
of  cones  affected  is  decreased,  and  thus  the  size  of  the  object 
seen  is  apparently  diminished. 


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.-..-  ■  \ 

J'lO.  100. — A.  Vei'tical  section  of  the  retina.     B.   Connection  of  the  rods  and  cones  of  ' 
(H.  Miiller.)                                   the  retina  with  the  nervous  elements. 

(Sappey.)  ; 

A.  1,  1,  layer  of  rods  and  cones;  2,  rods;  3,  cones;  4,  4,  5,  6,  external  granule  layer; 

7,  inter-granule  layer  (cone-fiber  pjexus);  8,  internal  granule  layer;  9,  10,  finely 

granular  gray  layer;  11,  layer  of  nerve  cells;  12,  12,  12,  12,  14,  14,  fibers  of  the  ; 

optic  nerve  ;  13,  membrana  limitans.  I 

B.  1,  1,  2,  3,  rods  and  cones,  front  view;  4,  K,  6.  rods,  side  view;  7,  7,  8,  8,  cells  of  • 

the  external  and  internal  granule  layers ;  9,  cell,  connected  by  a  filament  with  snb-  i 
jacent  cells;  10,  13,  nerve  cells,  connected  with  cells  of  the  granule  layers;  11,  21, 

filaments  connecting  cells  of  the  external  and  internal  granule  lavers  (12  is  not  in  ■ 

the  figure);  14,  15,  16,  17,  18,  19,  20,  22,  23,  24,  25,  26,  a  rod  and  a  cone,  con-  j 

nected  with  the  cells  of  the  granule  layers,  with  the  nerve  cells,  and  with  the  nerve  | 
fibers. 

In  cases  where  complete  blindness,  even  to  the  sensation  ! 

of  light,  exists,  as  sometimes  occurs  in  amaurosis,'  the  eyes  j 


'  For  the  causes  of  this  condition,  see  page  373  of  this  volume. 


PARALYSIS  OF  THE  THIRD  NERVE.  39I 

remain  fixed  and  immovable,  gazing  steadily  forward,  even 
when  objects  are  made  to  pass  before  the  vision  ;  while  in 
cases  of  partial  bKndness,  which  prevent  the  perception  of 
outline,  but  still  allow  of  the  perception  of  passing  objects 
between  the  light  and  the  retinae,  by  the  shadow  which  they 
throw,  the  eye  involuntarily  moves  in  a  direction  which  cor- 
responds to  that  of  the  moving  object. 

Cases  in  which  the  third  nerve  has  been  impaired  by  pres- 
sure or  disease,  or  totally  destroyed  by  section,  are  character- 
ized by  a  falling  of  the  upper  eyelid  over  the  pupil,'  and  an 
inability  to  raise  it,  owing  to  the  inaction  of  its  levator  mus- 
cle, so  that  the  eye  appears  constantly  half  shut.  This  con- 
dition is  known  by  the  name  of  "ptosis.'^''  The  movements 
of  the  eyeball  are  also  nearly  suspended,  and  permanent  ex- 
ternal strabismus  takes  place,  owing  to  the  paralysis  of  the 
internal  rectus  muscle,  while  the  external  rectus,  animated  by 
a  different  nerve,  preserves  its  activity.  From  paralysis  of 
the  fibers  distributed  to  the  iris,  a  dilatation  of  the  pupil  is 
also  produced,  and  accommodation  of  the  injured  eye  for  near 
objects  is  no  longer  performed. 

While  the  upper  eyelid  is  partially  raised  by  the  levator 
palpebrse  muscle,  which  is  supplied  by  the  third  nerve,  it  is 
also  raised  by  means  of  muscular  fibers,  which  are  governed 
by  the  cervical  sympathetic.  A  similar  set  of  fibers  exists  in 
the  lower  eyelid,  and  is  governed  by  the  same  nerves ;  and  it 
is  probably  through  the  influence  of  the  sympathetic  system 
that  the  eye  is  opened.  In  the  act  of  winking,  where  the 
shutting  of  the  eye  is  usually  affected  more  rapidly  than  the 
opening,  a  contrast  is  afforded  between  the  action  of  the  cra- 
nial nerves  and  those  of  the  sympathetic,  since  closing  of  the 
eye  is  performed  by  the  facial  nerve." 

External  strabismus  may  often  occur  without  the  condi- 
tion of  ''ptosis"  being  present,  the  filament  to  the  levator 
palpebrse  muscle  not  being  affected. 

When  all  the  muscles  supplied  by  the  third  nerve  are 

^  So  marked  is  this  deformity  that  the  upper  lid  frequently  almost  touches  the 
lower  lid.  ^  Mich.  Foster,  op.  cit. 


392  THE  CRANIAL  NERVES. 

paralyzed,  the  globe  of  the  eye  is  slightly  protruded,  from 
relaxation  of  most  of  its  muscles. 

In  strabismus,  or  squint,  an  optical  defect'  is  usually 
present.  So  large  is  the  percentage  of  optical  error  in  those 
cases  where  the  eyes  turn  inward  toward  the  nose,  that  this 
condition  seldom  exists  without  an  accompanying  hyperopia 
or  far-sightedness,  due  to  a  diminution  of  the  antero-posterior 
axis  of  the  eye  ;  while  in  external  squint,  where  the  eye  looks 
away  from  the  nose,  the  opposite  condition  of  myopia,  or 
near-sightedness,  is  often  present,  but  perhaps  not  in  as  large 
a  percentage  of  cases  as  in  the  opposite  deflection  of  the  eye. 
For  this  reason,  operations  are  often  of  little  benefit  when 
performed  for  the  relief  of  strabismus,  unless  the  error  in 
vision  is  accurately  determined  and  corrected  by  the  appro- 
priate lenses. 

DISEASES   OF  THE   OCULAR   MUSCLES   AND  THEIR   CAUSES. 

The  muscles  of  the  orbit  may  present  the  conditions  of 
spasm,  contracture,  motor  irritation,  or  paralysis. 

The  condition  of  "  nystagmus  "  is  characterized  by  clonic 
spasm  of  the  external  ocular  muscles,  and  by  peculiar  oscilla- 
tions or  involuntary  movements  of  the  organ.  It  is  always  a 
bilateral  affection,  and  its  starting-point,  according  to  the  ex- 
periments of  Adamuk  and  Ferrier,''  seems  to  be  situated  within 

'  Bee  Haynes  Walton,  Stellwaj^,  and  others.  In  speaking  of  this  optical  defect,  depen- 
dent upon  simple  hyperopia.  Dr.  Loring  says,  in  an  article  previously  quoted  in  this  vol- 
ume :  "  I  have  known  boys  of  eight  or  ten  years  of  age  to  beg  their  parents  to  let  them 
undergo  the  pain  of  an  operation  to  rid  themselves  of  a  deformity  which  subjects  them  so 
often  to  the  unfeeling  remarks  of  their  elders,  usually  friends  of  the  family,  as  well  as 
the  uneuphonious  but  expressive  titles  bestowed  upon  them  by  their  own  contemporaries, 
of  goggle-eye  and  cock-eye.  Xor  does  this  end  with  childhood.  The  deformity  is  a  dis- 
advantage to  him  through  life.  It  pursues  him  in  his  business  and  in  his  profession. 
Cheated  of  feature  by  dissembling  nature,  he  is  often  thought  to  be  dissembling  himself, 
when  nothing  is  further  from  his  thoughts.  How  often  do  we  hear  people  say  of  another, 
whom  we  know  to  be  perfectly  upright  and  trustworthy,  that  they  do  not  like  him  because 
he  never  looks  them  squarely  in  the  face !  And  it  is  a  little  curious  that  precisely  here  it 
is  that  the  lesser  degrees  of  the  trouble  produce  the  most  effect.  That  peculiar  expression 
which  people  complain  so  much  of  is  generally  due  to  a  deviation  in  the  axes  of  the  eyes 
— a  slight  convergence,  which  is  never  very  conspicuous,  and  at  times  only  to  be  detected 
by  a  trained  eye,  but  which,  nevertheless,  produces  in  all  a  very  disagreeable  impression, 
although  not  marked  enough  to  betray  its  cause." 

*  Discussed  in  the  previous  section. 


CAUSES  OF  PARALYSIS  OF  THE  THIRD  NERVE.        393 

the  anterior  tubercula  quadrigemina.  It  may  be  produced  by 
causes  affecting  either  the  central  nerve  ganglia,  the  periphe- 
ral nerves,  the  refracting  media  of  the  eye,  or  the  retina.  We 
thus  find  it  existing  in  connection  with  meningitis,  hydro- 
cephalus, etc.,  in  uterine  diseases,  worms,  dentition,  caries 
of  the  teeth,  etc.,  and  in  some  of  the  diseases  of  the  eye  or 
optic  nerve. 

Spasm  of  i'he  fibers  of  the  iris  is  observed,  in  rare  cases,  to 
exist  in  connection  with  some  irritative  condition  of  the  cere- 
bro-spinal  system,  which  has  involved  the  cilio-spinal  center 
of  the  spinal  cord.' 

By  contracture  of  a  muscle  is  meant  a  permanent  shorten- 
ing, in  contrast  to  its  temporary  shortening  when  under  the 
ordinary  influence  of  the  motor  stimulus.  It  occurs,  in  the 
ocular  group  of  muscles,  as  the  result  of  the  direct  irritation 
following  some  pathological  process,  at  a  seat  more  or  less 
distant  from  the  orbit ;  or  as  the  effect  of  prolonged  paralysis 
of  some  of  the  antagonistic  muscles. 

In  those  cerebral  and  spinal  conditions  in  which  convulsive 
attacks  are  produced,  and  in  attacks  of  hysteria,  the  evidences 
of  well-marked  motor  irritation  of  the  ocular  muscles  are 
often  observed. 

Paralysis  of  the  ocular  group  of  muscles  may  vary  in 
degree,  thus  constituting  either  paresis  or  true  paralysis  ;  also 
in  extent,  thus  affecting  all  the  muscles  supplied  by  the  third 
nerve,  and  often  the  fourth  and  sixth  nerves  as  well,  or,  again, 
only  separate  muscles  ;  and  finally  in  duration  and  its  sus- 
ceptibility to  treatment.  This  symptom  may  be  either  an 
initial  symptom,  or  a  complication  of  some  central  disease,  or 
the  result  of  peripheral  causes. 

Paralysis  of  the  muscles  supplied  by  the  third  nerve  is 
most  frequently  produced  by  the  following  causes  :  Circum- 
scribed meningeal  processes  at  the  base  of  the  skull ;  tu- 
mors, softening,  and  haemorrhage  of  the  cerebral  peduncles ; 
softening  and  haemorrhage  of  the  cerebral  ganglia ;    syphi- 

^  For  details  as  to  the  situation  and  function  of  this  center,  the  reader  is  referred  to 
subsequent  pages  of  this  volume. 


394  THE  CRANIAL  NERVES. 

lis  (affecting  the  cranial  or  orbital  cavity)  ;  orbital  tumors  ; 
diphtheria  ;  and,  finally,  aneurisms  of  the  carotid  (as  reported 
by  Leber t ').  In  the  development  of  ataxia^  the  third  nerve 
may  become  paralyzed  simultaneously  with  other  nerves  of  the 
cranium,  or,  possibly,  without  other  nerves  being  affected, 
and  the  same  condition  may  follow  the  prolonged  use  of  co- 
nium  or  gelsemium. 

When  the  paralysis  of  the  third  nerve  is  produced  by  intra- 
cranial lesions,  the  paralysis  is  liable  to  be  bilateral  or  to  tend 
toward  a  symmetrical  development  as  the  disease  progresses  ; 
while  the  fourth  and  sixth  nerves  are  often  subsequently  af- 
fected. There  are  also  other  symptoms,  of  great  value  in 
deciding  upon  the  existence  of  intra- cerebral  disease,  which 
may  be  present,  such  as  the  coexistence  of  cephalalgia,  ver- 
tigo, symptoms  of  neuro-retinitis,  disturbances  of  speech  and 
of  the  intellectual  faculties,  convulsive  movements  of  a  local 
or  general  type,  a  sense  of  weight  in  the  limbs,  or,  possibly, 
the  presence  of  paresis  or  paralysis  of  the  muscles  of  the 
extremities. 

"  A  very  large  proportion  of  tabetic  patients  tell  of  past  or 
present  diplopia,  and,  in  a  certain  number  of  cases,  the  ocular 
paralysis  precedes  the  pains  and  ataxia  by  several  years.  So 
true  is  this  statement,  that  it  has  become  an  established  prac- 
tice with  neurologists  and  ophthalmologists  to  suspect  poste- 
rior spinal  sclerosis  in  adults  who  present  themselves  with 
strabismus,  diplopia,  or  ptosis.  In  such  a  case  we  should 
carefully  question  the  patient  about  the  occurrence  of  fulgu- 
rating pains,  and  test  the  pupillary  and  tendinous  reflexes.  I 
need  hardly  add  that  another  obligatory  line  of  inquiry  in 
such  cases  is  with  reference  to  symptoms  of  syphilis."  ' 

The  same  remarks  apply  to  atrophy  of  the  optic  nerve, 
which  is  occasionally  an  early  symptom. 

It  is  not  infrequent  for  lesions  of  the  spinal  cord  to  pro- 
duce paralysis  of  the  ocular  muscles.  The  presence  of  such 
an  exciting  cause  may  be  surmised  by  the  coexistence  of  vague 
neuralgias  in  the  branches  of  the  cervical  or  brachial  plexuses, 

'  Quoted  by  Rosenthal.  «  E.  C.  Seguin,  "  Med.  Record,"  1881. 


TEE  FOURTH  CRANIAL  NERVE.  395 

or  in  the  sciatic  nerves  ;  of  abnormal  sensations  in  the  back, 
knees,  and  soles  of  the  feet ;  seminal  emissions,  frequent  or 
prolonged  erections,  or  diminished  sexual  power;  extreme 
sensitiveness  to  moisture  of  the  atmosphere  or  winds ;  a 
tendency  to  fatigue,  often  present  after  a  night's  repose; 
and  an  increase  in  the  galvano-excitability  of  the  main  nerve 
trunks. 

Paralysis  of  the  ocular  muscles  may  accompany  glosso- 
lahio-pJiaryngeal  paralysis  (Duchenne's  disease'),  if  the  cen- 
ter for  the  movements  of  the  eye  be  aifected  at  the  same  time 
as  the  centers  of  the  muscles  of  speech  and  deglutition ;  in 
this  case,  the  third  and  sixth  nerves  are  frequently  affected 
simultaneously.  The  same  condition  of  the  ocular  muscles 
may  also  accompany  ataxic  symptoms  of  cerebral  origin. 

Rheumatism  may  produce  ocular  paralysis.  This  cause  is 
to  be  suspected  when  no  symptoms  exist  which  seem  to  point 
to  local  trouble  in  the  orbit  or  brain.  It  is  found  to  affect  the 
motor  oculi  and  the  abducens  nerves  more  frequently  than  the 
patheticus. 

Diplopia  and  strabismus  are  often  the  first  symptoms  of 
cerebral  diseases  or  ataxia,  since  they  may  appear  before  the 
other  parts  of  the  muscular  system  are  affected.  If  they  show, 
at  times,  a  tendency  toward  spontaneous  retrogression,  and 
again  return  with  the  simultaneous  occurrence  of  neuralgic 
pain,  the  development  of  a  cerebral  lesion  is  rendered  stiU 
more  probable. 


THE  FOURTH   (TROCHLEAR   OR  PATHETIC)    NERVE. 

The  apparent  origin  of  this  nerve  is  from  the  superior 
peduncle  of  the  cerebellum^  and  it  then  winds  around  it,  pass- 
ing close  to  the  posterior  border  of  the  pons  Varolii.  The 
deep  fibers  of  this  nerve  may  be  traced  to  four  different  situ- 
ations, as  follows  :  1,  some  to  the  substance  of  the  peduncle ; 

^  The  symptoms  of  this  condition  will  be  found  mentioned  in  more  detail  in  connec- 
tion with  the  hypoglossal  nerve. 


396 


THE  CRANIAL  NERVES. 


2,  other  fibers  to  the  valve  of  Vieussens,  where  they  are  lost, 
with  the  exception  of  a  few,  which  can  be  traced  to  the  frenu- 
lum ;  3,  a  few  fibers  to  the  tuber cula  quadrigemina ;  4,  a 
large  bundle,  which  pass  inward  toward  the  median  line  and 
then  decussate  with  corresponding  filaments  of  the  opposite 
side.     The  nucleus  of  the  nerve  is  shown  in  Fig.  75. 

This  decussation  of  the  fibers  of  the  nerve  is  for  the  same 
physiological  reason,  as  was  mentioned  in  connection  with  the 

preceding  nerve,  viz. ,  to  afford 
harmony  of  action  between 
the  two  sides,  when  the  eyes 
are  compelled  to  remain  fixed 
upon  an  object  during  move- 
ments of  the  head. 

From  the  point  of  appar- 
ent origin,  the  nerve  passes 
forward  along  the  outer  wall 
of  the  cavernous  sinus,  where 
it  lies  below  the  third  nerve 
and  above  the  ophthalmic 
branch  of  the  fifth  nerve,  and 
escapes  from  the  cavity  of  the 
cranium,  through  the  highest 
part  of  the  sphenoidal  fissure, 
into  the  cavity  of  the  orbit. 
The  question  of  the  func- 


Fio.  101. — Distribution  of  the  paiheticus. 
(Hirschfeld.) 

1,  olfactory  nerve;  II,  optic  nerves ;  III,  mo- 
tor oculi  communis ;  IV,  pafheticicSy  hi^  the 
side  of  the  ophthalmic  h^anch  of  ihefifth^ 
and  passing  to  the  superior  oblique  muscle; 
VI,  motor  oculi  externus  ;  1,  ganglion  of 
Gasser;  2,  3,  4,  5,  6,  7,  8,  9,  10,  ophthal- 
mic division  of  the  fifth  nerve,  with  its 
branches. 


tion  of  this  nerve  resolves  it- 
self simply  into  the  mode  of  action  of  the  superior  oblique 
muscle.  This  muscle  arises  just  above  the  inner  margin  of 
the  optic  foramen,  and  passes  forward  along  the  upper  wall 
of  the  orbit,  at  its  inner  angle,  to  a  little  cartilaginous  ring, 
which  serves  as  a  pulley  for  its  tendon.  Its  tendon  becomes 
rounded  just  before  it  passes  through  this  ring,  where  it  makes 
a  sharp  curve,  passes  outward  and  slightly  backward,  and  be- 
comes spread  out,  to  be  attached  to  the  globe,  at  the  superior 
and  external  part  of  its  posterior  hemisphere.  It  is,  there- 
fore, the  direct  antagonist  of  the  inferior  oblique  muscle. 


THE  FIFTH  CRANIAL  NERVE,  397 

In  its  function,  it  is  purely  a  motor  nerve,  but  it  receives 
a  few  recurrent  fibers  from  the  fifth  nerve,  which  are  sen- 
sory. 

When  this  nerve  is  paralyzed,  the  position  of  the  eye 
shows  no  apparent  change,  except  when  the  head  is  moved 
from  side  to  side,  in  which  case  the  eye  moves  loitJi  the  head ; 
the  absence  of  the  usual  compensating  movement  of  the  eye, 
which  accompanies  all  the  movements  of  the  head,  being  de- 
stroyed in  consequence  of  the  paralysis  of  the  superior  oblique 
muscle,  which  greatly  assists  in  this  act.  The  patient  also 
sees  a  double  image,  whenever  attempts  are  made  to  look 
straight  forward,  or  at  objects  situated  toward  the  paralyzed 
side ;  but  the  image  becomes  a  single  one  when  the  head  is 
turned  toward  the  sound  side  to  view  any  object ;  hence  this 
abnormality  of  attitude  of  the  head  is  usually  present.' 


THE  TRIGEMINUS,  OR  FIFTH  NERVE. 

This  important  nerve  has  its  apparent  origin  within  the 
cranium  from  the  lateral  aspect  of  the  pons  Varolii^  although 
its  deep  fibers  have  been  traced  to  distinct  nuclei,  situated  in 
the  floor  of  the  fourth  ventricle  near  to  the  gray  tubercle  of 
Kolando  and  to  more  distant  parts.'  It  is  a  mixed  nerve, 
having  a  distinct  motor  and  sensory  root;  and  thus  possesses 
both  afferent  fibers,  through  which  sensory  impressions  are 
transmitted  to  the  brain,  and  efferent  fibers,  by  which  motor 
impulses  are  transmitted  from  the  brain  to  the  periphery  of 
some  branches  of  the  nerve. 

The  intimate  relations  which  the  nerve  bears  with  the 
points  of  origin  of  the  sixth,  seventh,  eighth,  ninth,  tenth, 
eleventh,  and  twelfth  cranial  nerves  in  the  floor  of  the  fourth 
ventricle  possibly  explain  many  of  those  phenomena  which 
are  considered  as  reflex  in  character,  and  whose  starting-point 

*  For  other  examples  of  this  diagnostic  guide  in  paralysis  of  ocular  muscles,  see 
previous  pages  upou  the  third  cranial  nerve. 

2  See  pages  which  relate  to  the  medulla  oblongata,  and  also  preceding  pages  of  this 
section  that  treat  of  the  deep  origins  of  the  fifth  nerve. 
28 


398 


THE  CRANIAL  NERVES. 


seems  to  depend  upon  some  irritation  of  the  fifth  nerve  by 
means  of  various  branches. 

The  two  roots  of  this  nerve  pass  forward,  side  by  side, 
as  far  as  the  petrous  portion  of  the  temporal  bone.  At  this 
point  a  marked  enlargement,  called  the  ganglion  of  Gasser,  is 
developed  upon  the  sensory  root;  and  subsequently  this  root 


Fia.  102, — OpJiihalmic  division  of  tlu  fifth.     (Hirschfeld.) 

1,  ganglion  of  Oasser;  2,  ophthalmic  divisvim  of  tJie  fifth  ;  3,  lachrymal  branch  ;  4,  frontal 
branch;  5,  external  frontal ;  6,  internal  frontal ;  7,  supra-trochlcar ;  8,  nasal 
branch;  9 ^  external  nasal;  10,  internal  nasal;  11,  anterior  deep  temporal  nerve; 
12,  middle  deep  temporal  nerve;  13,  posterior  deep  temporal  nerve;  14,  origin  of 
the  superficial  temporal  nerve  ;  15,  great  superficial  petrous  nerve.  I  to  XII,  roots 
of  the  cranial  nerves. 

divides  into  three  large  nervous  trunks  called,  respectively, 
the  ophthalmic,  the  superior  maxillary,  and  the  inferior  max- 
illary nerves,  which  escape  from  the  cavity  of  the  cranium 
through  different  foramina.*  The  motor  root  accompanies  the 
inferior  maxillary  nerve  until  it  has  escaped  from  the  cranium, 
when  it  unites  with  it. 


'  The  sphenoidal  fissure,  foramen  rotundum,  and  foramen  ovale  respectively  aflFord  a 
passage  for  these  branches  from  the  cranium. 


FUNCTION'S   OF  THE  FIFTH  NERVE. 


399 


TABLE   OF  THE   DISTRIBUTION   OF  THE   FIFTH   CRANIAL   NERVE.' 
r  (1)  Lachrymal  branch. 


CO 

U 

I— I 
"^ 
W 

2 
2 

< 
< 

t-H 


a.  OPHTHAL- 
MIC NERVE. 


h.  SUPERIOR 
MAXILLARY^ 
NERVE. 


(2)  Frontal  branch.  \  Supra-orbital  nerve. 
'  {  fcupra -trochlear  nerve. 

r  Ganglionic  nerve  (to  ciliary  ganglion). 
Long  ciliary  nerves. 
Infra-trochlear  nerves. 
t  (3)  Nasal  branch.     \  Internal  set.  To  septum  of  nose. 

!To  mucous  mem- 
brane and  integu- 
ment of  nose. 

Orbital  or  Temporo-malar  nerve. 
Spheno-palatine  nerves  (to  Meckel's  gan- 
glion). 

.Posterior    dental  (  ^"P^^^^^^^    ^^e^**^ 
I      nerve  \      branches. 

[  (  Deep  dental  branches. 

In  the  infra-orbital  <  . 

canal    "^  Ulterior 

On  the  face. 


In  the  spheno-maxil- 
lary  fossa. 


1' 


c.  INFERIOR 
MAXILLARY -( 
NERVE. 


From    the 
trunk. 


From    the 
trunk. 


anterior 


posterior 


dental  nerve. 

Palpebral  branches. 

asal  branches. 
Labial  branches. 

r  (1)  Masseteric  branch. 

(2)  Deep  temporal,  -j  ^^*f  "?^  ^J"^"«^- 

{      '  I  Posterior  branch. 

(3)  Buccal  branch. 

(4)  Pterygoid.  -j  Internal  branch 

/  External  branch. 
r(l)  AuRicuLO  -  tem- j  Auricular. 
PORAL  nerve.    I  Temporal. 

(2)  Gustatory  nerve. 
(  Mylo-hyoid. 

(3)  Inferior  dental!  Incisor. 

nerve.  I  Mental. 

I  Dental. 


From  anatomical  points  whicli  have  been  mentioned,  and 
also  by  the  above  table,  the  fact  is  shown  that  the  ophthalmic 
and  the  superior  maxillary  nerves  possess  no  motor  power^ 
while  the  inferior  maxillary  nerve  is  both  motor  and  sensory 
in  its  function.  It  has  been  mentioned  in  previous  pages, 
however,  that  a  vaso-motorial  influence  is  possessed  by  the 
ophthalmic  nerve,  and  also  a  direct  power  of  dilating  the 
pupils  ;  but  these  effects  are  unquestionably  dependent  upon 
filaments  given  to  it  by  the  sympathetic  nerve. 

The  ultimate  distribution  of  the  three  branches  of  the  fifth 
nerve  may  possibly  be  made  more  clear  by  grouping  together 
the  efferent  and  afferent  fibers,  and  thus  separating  the  parts 


Copied  from  "Essentials  of  Anatomy"  (Darling  and  Ranney),  New  York,  1880. 


400 


THE  CRANIAL  NERVES. 


Fig.  103. — A  diagram  of  the  distribtition  of  the  fifth  nerve} 

1,  the  crm  cerebri  ;  2,  the  sensory  root  of  the  nerve ;  3,  the  motor  root  of  the  nerve  ;  4, 
the  Gasserian  ganglion^  upon  the  sensory  root  only ;  5,  the  ophthalmic  nei've,  passing 
through  the  sphenoidal  fissure ;  6,  the  superior  maxillary  nerve,  passing  through  the 
foramen  rotundum,  to  enter  the  spheno-maxillary  fossa ;  7,  the  inferior  maxillary 
nerve,  passing  through  the  foramen  ovale  in  company  with  the  motor  root,  which 
soon  joins  it ;  8,  a  filament  sent  backward  from  the  ophthalmic  nerve  to  the  tento- 
rium cerebelli ;  9,  the  frontal  nerve  ;  10,  the  lachrymal  nerve  ;  11,  the  nasal  nerve; 
12,  the  supra-orbital  nerve,  passing  through  the  foramen  of  the  same  name  ;  13,  the 
supra-trochlear  nerve;  14:,  the  long  ciliary  nerves  to  the  iris;  15,  the  lenticular,  ov 
ciliary  ganglion  ;  16,  the  temporo-malar  nerve,  showing  its  division  into  the  temporal 
branch  and  the  malar  branch;  17, the  spheno-palatine  nerves,  going  to  Meckel's  gan- 
glion ;  18,  the  posterior  dental  nerves,  given  off  just  before  the  superior  maxillary  nerve 
enters  the  infra-orbital  canal,  after  passing  through  the  spheno-maxillary  fossa  ;  19, 
the  anterior  dental  nerves,  given  off  in  the  antrum  ;  20,  the  nano-palatine  ne^'ve,  es- 
caping at  the  anterior  palatine  foramen,  after  passing  through  the  antrum ;  21,  the 
anterior  palatine  nerves,  after  escaping  from  the  posterior  palatine  foramen  ;  22,  the 
deep  temporal  nerve  ;  23,  the  masseteric  branch  ;  24,  the  buccal  branch,  which  often 
also  supplies  the  external  pterygoid  muscle ;  25,  the  pterygoid  branch,  going  chiefly 
to  the  internal  pterygoid  muscle ;  26,  the  posterior  palatine  nerves,  after  escaping 
from  the  posterior  palatine  foramen,  going  to  the  muscles  of  the  soft  palate ;  27,  the 
auriculo-temporal  ne^-ve,  splitting  and  thus  embracing  the  middle  meningeal  artery ; 

28,  the  gmtatory  or  lingual  nerve,  distributed  to  the  anterior  two  thirds  of  the  tongue  ; 

29,  the  inferior  dental  nerve,  passing  through  the  inferior  dental  canal,  beneath  the 
teeth  of  the  lower  jaw ;  30,  the  mylo-hyoid  nerve,  a  branch  of  the  inferior  dental 
nerve;  31,  the  chorda  tympani  nerve,  joining  the  gustatory  nerve,  and  possibly  bring- 
ing to  it  the  perception  of  taste  ;  32,  the  middle  meningeal  artery ;  33,  the  fibers  going 
to  the  carotid  and  cavernous  plexuses  of  the  sympathetic  system ;  34,  the  Vidian 
nerve,  going  from  Meckel's  ganglion  to  the  Vidian  canal.  Ganglia  of  the  fifth  nerve. 
— L,  The  lenticular  ganglion,  sending  fibers  to  iris  and  ciliary  muscle ;  c,  the  Gasse- 
rian ganglion  ;  o,  the  ofic  ganglion,  lying  cm  the  inferior  maxillary  nerve  below  the 
foramen  ovale  ;  s,  the  suhmaxillary  ganglion,  connected  with  the  gustatory  and  chorda 
iympani  nerves ;    m,  Meckel's  ganglion,  lying  in  the  spheno-maxillary  fossa. 


*  Modified  from  Flower  by  the  author. 


DISTRIBUTION  OF  THE  FIFTH  NERVE. 


401 


whicli  are  supplied  alone  with  sensation  from  those  to  which 
the  motor  root  is  eventually  distributed. 

The  efferent  fibers  of  the  fifth  pair  give  motor  power  to 
the  muscles  of  mastication,  viz.,  the  temporal,  masseter,  and 


Fig.  104. — Inferior  maxillary  division  of  tJie  fifth.     (Hirschfeld.) 

1,  branch  from  the  motor  root  to  the  masseter  muscle ;  2,  filaments  from  this  branch  to 
the  temporal  muscle ;  3,  buccal  branch  ;  5,  6,  7,  branches  to  the  muscles ;  8,  auri- 
culo-temporal  nerve ;  'Q^  temporal  branches ;  10,  auricular  branches;  II ,  anastomosis 
with  the  facial  nerve  ;  12,  Ungual  branch  ;  13,  branch  of  the  motor  root  to  the  mylo- 
hyoid muscle;  14,  15,  15,  inferior  dental  nerve,  with  its  branches ;  16,  mental  branch; 
17,  anastomosis  of  this  branch  with  the  facial  nerve. 


pterygoids  ;  also  to  the  mylo-hyoid  and  anterior  belly  of  the 
digastric,  and  to  the  tensor  palati  and  tensor  tympani.  They 
thus  control  not  only  the  physiological  act  of  mastication, 
but  also,  to  some  extent,  the  acts  of  deglutition  and  hearing. 
These  fibers  furthermore  afford  a  xaso-motor  influence  over 
various  vessels  in  certain  regions  of  the  head  and  face.  Secre- 
tory  fibers  to  the  lachrymal  gland,  and,  according  to  some 


402  THE  CRANIAL  NERVES, 

authors,  to  the  parotid  and  submaxillary  glands,  by  means  of 
fibers  derived  from  the  facial  nerve  (through  the  chorda  tym- 
pani  branch),  are  attributed  to  the  trigeminus.  By  these  fibers, 
the  secretions  necessary  to  the  perfect  performance  of  the 
parts  supplied  by  the  fifth  nerve  are  also  placed  under  its 
control,  thus  illustrating  again  that  beautiful  law  of  Nature 
in  arranging  the  nerves  in  accordance  with  harmony  of  action. 
Beside  the  efferent  fibers  possessed  by  the  fifth  nerve,  there 
exist  in  addition  certain  unnamed  fibers  which  control  the 
proper  nutrition  of  the  eye,  nose,  and  other  portions  of  the 
face.  These  latter  fibers  are  not  as  yet  fully  ascertained  so 
as  to  be  described  in  detail,  but  their  existence  seems  indi- 


FiG.  105. — Superior  maxillary  division  of  the  fifth.     (Hirschfeld.) 

1,  ganglion  of  Gasser ;  2,  lachrymal  branch  of  the  ophthalmic  division  ;  3,  superior  max- 
illary division  of  the  fifth  ;  4,  orbital  branch  ;  5,  lachrymo-palpebral  filament ;  6, 
malar  branch  ;  7,  temporal  branch  ;  8,  spheno-palatine  ganglion  ;  9,  Vidian  nerve ;  10, 
great  superficial  petrosal  nerve;  11,  facial  nerve;  12,  branch  of  the  Vidian  nerve ; 
13,  anterior  and  two  posterior  dental  branches ;  14,  branch  to  tJie  mucous  membrane  of 
the  alveolar  processes  ;  15,  terminal  branches  of  t/ie  superior  maxillary  division  ;  16, 
branch  of  the  facial. 

cated  by  the  fact  that,  after  section  of  the  fifth  nerve,  the 
cornea  becomes  cloudy ;  the  whole  eye  becomes  inflamed, 
only  to  subsequently  disorganize ;  the  mucous  membrane  of 
the  nose  is  similarly  destroyed,  and  ulcers  frequently  make 
their  appearance  upon  the  mucous  membrane  of  the  lips  and 
gums.     Snellen,  however,  considers  these  changes  as  the  ef- 


AFFERENT  FIBERS   OF  THE  FIFTH  NERVE.  498 

fects  of  the  mechanical  irritation  of  dirt,  which  the  mucous 
membranes,  no  longer  possessing  sensibility,  are  unable  to 
perceive. 

The  afferent  fibers  of  the  fifth  nerve  afford  general  sensa- 
tion to  the  entire  skin  of  the  head  and  face,  except  in  the 
occipital  region  and  the  back  and  lower  part  of  the  ear,' 


Fig.  106. — Superficial  branches  of  the  facial  and  the  fifth.     (Hirschfeld.) 

1,  trunk  of  the  facial ;  2,  posterior  auricular  nerve  ;  3,  branch  which  it  receives  from  ihc 
ce^'vical  plexus  ;  4,  occipital  branch  ;  5,  6,  branches  to  the  muscles  of  the  ear  ;  1,  digas- 
tric branches  ;  8,  branch  to  the  stylo-hyoid  muscle  ;  9,  superior  terminal  branch  ;  10, 
temporal  branches  ;  W^  frontal  branches  ;  12,  branches  to  the  orbicularis  palpebrarum  ; 
13,  nasal .^  or  suborbital  branches  ;  14,  buccal  branches  ;  15,  inferior  terminal  branch  ; 
16,  mental  branches  ;  17,  cervical  branches  ;  18,  superficial  temporal  nerve  (branch  of 
the  fifth);  19,  20,  frontal  nerves  (branches  of  the  fifth);  21,  22,  23,  24,  25,  26,  27, 
branches  of  the  fifth  ;  28,  29,  30,  31,  32,  branches  of  the  cervical  nerves. 

and  also  to  the  mucous  membranes  of  the  mouth,  with  the 
exception  of  the  posterior  pillar  of  the  fauces  and  the  poste- 

*  Hilton,  op.  cit. 


404:  THE  CRAMAL  NERVES. 

rior  third  of  the  tongue,  which  derive  their  sensation  by 
means  of  the  glosso-pharyngeal  nerves. 

The  accuracy  of  this  statement,  as  regards  the  distribution 
to  the  integument  of  the  ear,  which  is  now  accepted  by  most 
of  the  anatomical  authors  of  the  present  day,  was  strangely 
attested  to  by  facts  brought  under  the  notice  of  John  Hilton,' 
who  was  thus  enabled  clinically  to  verify  the  exact  distribu- 
tion of  the  fifth  nerve  to  the  pinna  and  the  auditory  canal. 
It  seems  that  an  attempt  was  made  by  a  criminal  to  kill  his 
wife  by  cutting  her  throat,  but  that  the  attempt  was  not  suc- 
cessful, and  resulted  in  severing  the  auricular  branch  of  the 
second  cervical  nerve^  which,  as  well  as  the  fifth  cranial  nerve, 
supplies  the  ear.  An  opportunity  was  thus  afforded  to  ex- 
amine, by  the  use  of  needle  points,  the  state  of  sensibility  of 
the  different  portions  of  the  ear,  and  to  decide,  by  the  loss 
of  sensibility,  the  exact  regions  which  the  second  cervical 
nerve  supplied.  It  was  thus  proven  that  the  upper  and  ante- 
rior part  of  the  ear,  and  also  the  auditory  canal,  was  sup- 
plied by  the  fifth  cranial  nerve ;  and  that,  therefore,  these 
parts  are  in  direct  nervous  communication  with  the  forehead, 
temple,  face,  nose,  teeth,  and  the  tongue. 

It  can  thus  be  easily  understood  why  pain  in  the  auricular 
region,  as  evidenced  in  cases  recited  later  on,  may  prove  a 
most  valuable  diagnostic  sign  of  irritation  of  some  of  the  other 
branches  of  the  fifth  nerv^e,  distributed  to  the  regions  which 
are  associated  by  means  of  this  nerve  with  the  ear,  although 
apparently  having  no  anatomical  relation  with  it. 

In  the  partly  diagrammatic  representation  of  the  distri- 
bution of  the  nerves  to  the  cutaneous  surface  of  the  head,  the 
outlines  of  the  various  regions,  represented  as  supplied  by 
the  different  nerves,  are  as  nearly  accurate  as  careful  investi- 
gation can  determine  them.'  It  will  be  perceived  that  nine, 
out  of  the  fourteen  regions  mapped  out  upon  the  head  and 
neck,  are  supplied  with  sensation  by  some  of  the  branches  of 

>  "  Rest  and  Pain,"  London  (New  York,  ISTO). 

'  As  the  boundaries  of  the  regions  supplied  by  any  nerve  gradually  shade  off  into 
neighboring  regions,  it  is  not  well  to  rely  upon  the  extreme  area  of  any  region  in  testing 
the  special  sensibility  of  any  nerve. 


CUTANEOUS  BRANCHES  OF  THE  FIFTH  NERVE.        405 

the  fifth  cranial  nerve^  while  the  remaining  five  are  supplied 
by  branches  of  the  cervical  plexus,  with  the  exception  of  that 
region  to  which  the  great  occipital  nerve  is  distributed. 

It  can  easily  be  understood,  from  what  has  already  been 


Fig.  107- — The  nervous  distribution  of  the  head.     (After  Flower,  but  slightly  modified.) 

1,  region  supplied  by  the  supra-orbital  branch  of  the  fifth  nerve ;  2,  region  supplied  by 
the  supra-trochlear  branch  of  the  fifth  nerve  ;  3,  region  supplied  by  the  infra-troch- 
lear  branch  of  the  fifth  nerve  ;  4,  region  supplied  by  the  infra-orbital  branch  of  the 
fifth  nerve ;  5,  region  supplied  by  the  buccal  branch  of  the  fifth  nerve  ;  6,  region  sup- 
plied by  the  mental  branch  of  the  fifth  nerve  ;  7,  region  supplied  by  the  superfdal 
cei'vical  from  the  cei'vical  plexus  ;  8,  region  supplied  by  the  great  auricular  from  the 
cervical  plexus ;  9,  i-egion  supplied  by  the  temporo-malar  branch  of  the  fifth  nerve ; 
10,  region  supplied  by  the  lachrymal  branch  of  the  fifth  nerve  ;  11,  region  supplied 
by  the  auriculo-temporal  branch  of  the  fifth  nerve ;  12,  region  supplied  by  the  ffreat 
occipital  (a  spinal  nerve) ;  13,  region  supplied  by  the  smaU  occipital  from  the  cervical 
plexus  ;  14,  region  supplied  by  the  supra-clavicular  from  the  cervical  plexus. 

said  as  to  the  manner  of  employing  the  nerves  as  guides  to 
diagnosis,  that  a  careful  study  of  the  limits  of  each  of  these 
regions  of  the  head  may  often  enable  the  physician  to  explain 
symptoms  which  might  otherwise  seem  obscure ;  and  also 
enable  him  to  use  the  symptom  of  local  pain,  whenever  pres- 
ent, as  a  signal  which  Nature  often  gives  of  disease  in  parts 
possibly  far  removed  from  the  seat  of  pain,  but  still  inti- 
mately connected  with  it  by  means  of  its  nervous  supply. 

EFFECTS   OF   SECTION"  OF  THE   FIFTH    J^TERVE. 

Many  points  of  practical  value  dependent  upon  the  fifth 
nerve  can  be  better  understood  when  the  effects  of  its  divis- 
ion have  been  considered  in  detail.  If  the  fifth  nerve  be 
divided,   sensation  is  immediately  destroyed   in    aU  those 


406  THE  CRANIAL  NERVES. 

portions  of  the  head  and  face  to  which  the  efferent  nerves 
are  distributed  ;  the  power  of  mastication  is  lost ;  the  secre- 
tions of  the  lachrymal,  parotid,  and  submaxillary  glands  are 
rendered  deficient ;  the  act  of  deglutition  becomes  imper- 
fect, since  some  of  the  muscles  required  for  its  performance 
are  paralyzed,  and  since  the  tongue  is  unable  to  perceive  the 
bolus  of  food,  and  therefore  can  not  properly  direct  its 
movements;  and,  finally,  hearing  is,  to  a  certain  extent, 
impaired,  since  the  tensor  tympani  muscle '  has  lost  its  motor 
power. 

In  addition  to  these  direct  effects  of  section,  secondary 
results  are  manifested  in  those  forms  of  ulceration  which 
have  been  previously  referred  to,  and,  eventually,  in  the  de- 
struction of  sight  and  smell. 

It  may  be  noticed  that  the  effect  of  section  of  the  fifth 
nerve  upon  the  special  sense  of  taste  has  not  been  mentioned. 
It  was  formerly  supposed  that  the  gustatory  fibers  of  the  fifth 
nerve  afforded  the  sense  of  taste  to  the  anterior  two  thirds  of 
the  tongue  ;  but  it  is  now  urged  by  many  that  the  fifth  nerve 
is  simply  a  nerve  of  sensation  to  that  organ,  and  that  its  fibers 
are  employed  exclusively  in  the  appreciation  of  the  sensations 
of  touch  and  feeling,  while  the  true  gustatory  fibers  of  that 
portion  of  the  tongue  are  derived  from  the  chorda  tympani 
branch  of  the  facial  nerve.  In  support  of  this  view,  cases  have 
been  observed  where  the  chorda  tympani  has  been  affected, 
either  by  disease  or  in  consequence  of  injury  within  the 
middle  ear,  and  the  sense  of  taste  has  been  impaired ;  but,  on 
the  other  hand,  cases  have  been  also  recorded  where  the  fifth 
nerve  was  alone  diseased,  and  yet  taste  was  destroyed  in  the 
anterior  two  thirds  of  the  tongue.  It  is  such  cases  as  the 
latter  that  still  lead  some  physiologists  to  believe  that  the 
chorda  tympani  nerve  only  controls  t\\Qflow  of  the  saliva^  and 
that  impairment  of  this  secretion  impairs  or  destroys  the  spe- 
cial sense  of  taste  afforded  by  the  gustatory  branch  of  the 
fifth  nerve. 

*  According  to  Lucae's  recent  experiments  ("  Berlin,  klin.  Wschr.,"  1874),  the  tensor 
tympani  muscle  presides  over  the  accommodation  for  mvMcal  tones. 


NEURALOIA    OF  TEE  FIFTH  NERVE.  407 

CLII^ICAL   POII^TS   AFFORDED   BY   THE   FIFTH   NERVE. 

The  fifth  nerve  may  be  the  seat  of  neuralgia,  spasm,  or 
paralysis.  The  type  of  neuralgia  (called  tic-douloureux,  the 
facial  pain  of  Fothergill,  and  "  prosopalgia  ")  dependent  upon 
the  fifth  nerve  affects  only  the  sensory  trunks  ;  the  spasms 
may  be  of  a  tonic  or  clonic  type,  and  are,  of  course,  confined 
to  the  muscles  supplied  by  the  motor  branches  of  the  nerve  ; 
while  the  paralytic  condition  can  affect  the  sensory  trunks, 
producing  anaesthesia  of  the  parts  to  which  the  affected  nerve 
is  distributed,  or  the  motor  filaments  may  be  impaired,  thus 
destroying  the  power  of  normal  movement  in  the  muscles  of 
mastication  and  the  mylo-hyoid.  So  many  points  of  clinical 
interest  and  practical  value  pertain  to  these  various  condi- 
tions that  each  will  be  considered  somewhat  in  detail. 

NEURALGIA   OF  THE  TRIGEMINUS  NERVE. 

The  various  forms  of  tic-douloureux  are  so  commonly  met 
with,  and  prove  so  obstinate  to  treatment,  as  well  as  distress- 
ing to  the  patient,  that  a  practical  knowledge  of  the  disease 
can  not  be  gained  without  a  careful  study  of  the  various 
causes  which  have  been  found  to  produce  it. 

Among  the  reported  cases  of  this  affection,  there  have 
been  discovered,  as  exciting  causes,  the  following  conditions  : 
Tumors  of  the  middle  fossa  of  the  skull  or  of  the  base  of 
the  brain,  producing  neuralgia  so  long  as  irritation  only  is 
produced,  but  anaesthesia  when  degeneration  of  the  nerve 
trunks  begins  ;  accumulations  of  pus  within  the  cranial  cav- 
ity ;  tumors  of  the  pons  Varolii  ;  morbid  processes  in  the 
regions  adjacent  to  the  ganglion  of  Gasser  ;  and  aneurism  of 
the  internal  carotid  artery  '  within  the  sella  turcica.  Diseases 
of  the  cervical  portion  of  the  spinal  cord,  if  high  up,  may  cre- 
ate neuralgia  of  the  fifth  pair,  by  irritating  the  fibers  of  that 
nerve  which  arise  from  the  lower  part  of  the  medulla.  Peri- 
ostitis of  the  bony  orifices,  through  which  the  various  branches 
of  the  fifth  nerve  pass,  may  create  such  pressure  as  to  produce 

^  Romberg's  case. 


408  THE  CRANIAL  NERVES. 

the  most  severe  and  persistent  neuralgias  ;  for  this  reason  the 
supra-orbital,  infra-orbital,  zygomatic,  superior  and  inferior 
dental  branches  are  more  liable  to  be  the  seat  of  pain  than 
the  branches  which  pass  through  such  large  openings  as  the 
sphenoidal  and  spheno-maxillary  fissures.'  Exostoses  of  the 
bones,  especially  of  the  upper  and  lower  jaws,  may  create  the 
most  severe  type  of  neuralgia  by  pressure  upon  the  neighbor- 
ing nerve  trunks.  Exposure  to  cold  or  dampness  will  pro- 
duce it,  being  one  of  the  most  frequent  of  the  trivial  causes. 
Finally,* inflammatory  changes  in  the  ganglia '  attached  to  the 
nerve,  the  enlargements  and  nodosities  found  upon  resected 
nerves,  an  exostosis  of  a  wisdom  tooth,'  caries  and  osteo- 
phytes of  the  bony  canals  through  which  branches  of  the 
nerve  pass,  and  neuroma  of  the  ganglion  of  Gasser  protrud- 
ing through  the  foramen  ovale,*  have  been  known  to  produce 
the  most  severe  neuralgia. 

The  symptoms  of  tic-douloureux  are  of  the  most  distressing 
character.  The  pain  is  usually  extremely  violent,  and  the 
patients  will  describe  it  to  you  as  of  a  burning,  piercing,  or 
shooting  character.  It  is  liable  to  be,  at  first,  paroxysmal ; 
but,  if  due  to  organic  disease,  it  may  gradually  become  more 
or  less  constant.  The  continuous  pain  is,  however,  usually 
limited  to  certain  well-defined  spots  of  extreme  sensitiveness 
to  pressure,  which  the  patient  can  readily  point  out  to  you 
(the  ''puncta  dolorosa  "  of  Yalleix).  Thus,  the  first  branch  of 
the  trigeminus  (the  ophthalmic)  presents  six  such  points,  each 
indicating  some  one  of  its  subdivisions.  These  are  situated, 
respectively,  over  the  supra-orbital  foramen  ;  in  the  center  of 
the  upper  eyelid ;  a  frontal  point  over  the  escape  of  the  nerve 
of  the  same  name  ;  one  at  the  outer  angle  of  the  eye,  for  the 
lachrymal  branch;  and  two  at  the  inner  angle  of  the  eye, 
upon  the  nose,  representing  the  inferior  trochlear  and  the 
ethmoidal  nerves. 

In  the  region  supplied  by  the  superior  maxillary  nerve 
and  its  branches,  there  may  exist  a  malar  point,  an  infra- 

'  Ilyrtl,  as  quoted  by  Rosenthal.  '  Cases  of  Carnochan  and  Wedl. 

'  Thompson,  as  quoted  by  Rosenthal.  *  Chouppe's  case. 


NEURALGIA   OF  THE  FIFTH  NERVE.  409 

orbital  point,  a  point  in  tlie  palate,  and  one  on  the  gum  of 
the  upper  jaw . 

In  the  region  supplied  by  the  inferior  maxillary  nerve, 
the  points  of  tenderness  are  situated  in  front  of  the  tragus 
of  the  ear  (the  temporal  point) ;  one  in  the  parietal  region, 
where  the  frontal,  occipital,  and  temporal  nerves  meet ;  one 
over  the  temporo-maxillary  joint ;  a  point  upon  the  tongue 
for  the  lingual  branch  ;  and  one  upon  the  integument  of  the 
chin,  for  the  mental  nerve. 

Painful  points  are  often  detected  by  pressure  in  the  region 
of  the  spinous  and  transverse  processes  of  the  cervical  verte- 
brae (the  ''point  apophysaire"  of  Trousseau). 

The^Qpuncta  dolorosa  are  usually  the  starting  points  for 
the  pain  of  the  acute  paroxysms,  from  which  the  pain  radiates 
along  the  course  of  the  nerves  of  the  region  affected.  In  some 
cases,  these  points  of  tenderness  may,  however,  be  absent,  when 
a  central  origin  of  the  disease  may  reasonably  be  suspected. 

The  relation  of  the  filaments  of  the  fifth  nerve  with  some 
vaso-motor  fibers  causes  this  type  of  disease  to  be  often  asso- 
ciated with  certain  disorders  of  secretion,  since  the  vessels  of 
the  glands  of  the  affected  region  are  liable  to  dilate  after  an 
acute  paroxysm  of  pain.  We  can  thus  explain  the  abundant 
flow  of  tears  after  an  attack  of  neuralgia  of  the  ophthalmic 
branch  ;  and  of  nasal  mucus  and  saliva,  when  the  second  and 
third  branches  of  the  trigeminus  are  involved.  Profuse  sweat- 
ing of  the  region  of  the  face  affected  is  also  sometimes  well 
marked  both  during  and  after  the  paroxysm. 

The  vaso-motor  communication  may  also  explain  why  we 
have  reported  cases  of  local  swelling,  redness,  elevation  of  the 
temperature,  and,  sometimes,  erysipelatous  inflammation  of 
the  affected  region  ;  and  why  the  hair  has  been  observed  to 
fall  out,  and  the  skin  to  become  discolored  and  roughened. 
Hypertrophy  of  the  cheek  has  been  noticed,  as  a  result  of  tic- 
douloureux,  by  Niemeyer,  Brodie,  Komberg,  and  Notta  ;  and 
ophthalmia  has  been  produced  by  a  similar  condition  confined 
to  the  first  branch  of  the  fifth  nerve.  When  the  nerve  trunks, 
which  at  first  were  the  seat  of  neuralgia,  become  destroyed  or 


416  THE  CRAKIAL  NERVES. 

seriously  impaired  by  pressure  or  granular  degeneration,  the 
face  may  undergo  atrophy. 

Neuralgias  of  tlie  fifth  nerve,  when  due  to  cerebral  tumors^ 
are  often  complicated  by  other  symptoms  which  greatly  assist 
in  the  diagnosis  ;  among  the  more  prominent  of  which  may  be 
mentioned  diplopia,  vertigo,  chronic  cephalalgia,  spasms  of 
certain  groups  of  muscles,  paralysis  of  various  types,  and  the 
absence  of  the  puncta  dolorosa,  whose  situations  have  already 
been  mentioned. 

Tic-douloureux  is  not  to  be  confounded  with  pain  depend- 
ent upon  the  decay  of  teeth,  inflammation  of  the  temporo- 
maxillary  articulation,  tumors  of  the  antrum,  or  extension  of 
inflammation  to  that  cavity  from  an  acute  attack  of  coryza, 
migraine,  or  the  facial  pains  of  lead  poisoning,  hysteria,  or 
spinal  affections.  It  is  more  common  in  women  than  in  men  ; 
and  most  frequent  between  the  ages  of  thirty  and  fifty.  It  is  j 
more  liable  to  occur  in  cold  months  than  when  the  weather  is  j 
warm  (provided  it  be  not  due  to  actual  disease) ;  and  it  may  { 
follow  traiimatism,  senile  changes  in  the  blood-vessels,  and  1 
malarial  poisoning. 

SPASM  DUE  TO  THE  TRIGEMINUS  NERVE.  ^ 

The  jaw  may  be  rendered  immovable,  as  in  tetanus,  by  the  : 

masseter,  temporal,  and  pterygoid  muscles,  all  of  which  are  \ 

supplied  with  motor  power  by  the  fifth  nerve.  The  same  form  \ 
of  spasm  may  be  occasionally  observed  in  attacks  of  hysteria. 

Clonic  spasm  of  the  temporal  and  masseter  muscles,  alter-  \ 

nating  with  that  of  the  depressors  of  the  jaw  (the  mylo-hyoid  I 

and  the  anterior  belly  of  the  digastric),  produces  the  chatter-  \ 

ing  of  the  teeth  so  often  seen  in  the  chill  of  inflammatory  dis-  ,■ 

eases  and  fevers  and  after  exposure  to  cold.  \ 

The  pterygoid  muscles,  by  a  tonic  contraction,  may  pro-  I 

duce  the  grinding  of  the  teeth ;  a  displacement  of  the  jaw  | 

to  one  side,  during  an  hysterical  paroxysm,  which  lasted  some  \ 

days,  is  reported  by  Leube.*  #. 

*  As  quoted  by  Rosenthal :  "  A  Clinical  Treatise  of  the  Diseases  of  the  Nervous  Sys-      "! 
tern"  (Putzel's  translation,  New  York,  1879).  1 


SPASM  AND  PARALYSIS   OF  THE  FIFTH  NERVE.        41I 

Spasms  of  the  muscles  supplied  by  the  trigeminus  may  be 
the  result  of  apoplexy,  cerebral  softening,  meningeal  exuda- 
tion, lesions  of  the  pons  Varolii  and  medulla  oblongata,  hys- 
teria, epilepsy,  tetanus,  hydrophobia,  tumors  irritating  the 
ganglion  of  Gasser,  peripheral  irritation,  reflex  causes  (as 
dental  pain,  ulceration  of  the  tongue  or  mouth,  intestinal  or 
uterine  irritation,  teething,  etc.),  and  rheumatism. 

In  rare  cases,  the  depressors  of  the  jaw  may  be  the  seat  of 
localized  spasm,  in  which  event  the  mouth  may  be  kept  wide 
open  for  a  longer  or  shorter  period. 

PARALYSIS   OF  THE  TRIGEMINUS   NERVE. 

It  is  a  rare  occurrence  to  observe  a  simultaneous  paraly- 
sis of  the  motor  and  sensory  roots  of  the  trigeminus.  An- 
aesthesia of  parts  supplied  by  the  branches  derived  from 
the  sensory  root  may  occur  from  central  causes,  and  is  per- 
haps more  frequent  than  those  symptoms  dependent  npon 
lesions  involving  the  motor  root.  In  lesions  confined  to  the 
cerebral  ganglia  or  cortex,  however,  the  motor  root  is  more 
often  impaired  than  the  sensory  portion,  while  the  sensory 
root,  or  some  of  its  branches,  is  frequently  affected  from 
causes  outside  of  the  cranial  cavity. 

In  studying  the  condition  of  trigeminal  anaesthesia,  it  must 
be  prefaced  that  the  regions  affected,  and  therefore  the  results 
of  the  impaired  nervous  function,  differ  with  the  exciting 
cause,  since  a  central  lesion  is  liable  to  involve  all  of  the  sen- 
sory branches  of  the  nerve ;  while  an  external  cause  usually 
affects  some  individual  branch. 

The  central  lesions  of  this  disease  comprise  apoplectic 
clots ;  destructive  lesions  producing  ataxia ;  hysteria ;  local 
diseases  or  exudations  which  involve  the  large  root  of  the  fifth 
nerve  between  the  pons  Varolii  and  the  ganglion  of  Gasser ; 
and  lesions  of  the  medulla  oblongata,  thus  affecting  its  fibers 
of  origin. 

Tlie  external  causes  include  all  forms  of  traumatism ; 
exposure  to  cold  or  heat ;  surgical  procedures  ;  caries  or  peri- 
ostitis of  the  bony  canals  ;  suppuration  of  the  soft  tissues  ad- 


412  THE  CRAKIAL  NERVES. 

joining  the  affected  nerve ;  local  tumors  and  inflammatory 
exudations ;  and  certain  blood  conditions  accompanied  by- 
nerve  sclerosis  (chiefly  Norwegian  leprosy).' 

The  condition  of  facial  anaesthesia  may  be  complete,  when 
sensibility  to  contact,  pain,  heat,  or  cold  is  abolished ;  or  par- 
tial, when  extreme  impressions  can  be  perceived,  and  often 
differentiated  as  to  the  peculiar  character  of  each.  The  needle 
points,  the  compass,  and  the  electric  brush  are  all  employed 
in  the  examination  of  such  a  patient,  in  order  to  decide 
as  to  the  extent,  character,  and  degree  of  the  existing  pa- 
ralysis. 

If  the  ophthalmic  nerve  be  the  seat  of  anaesthesia,  we  may 
observe  a  contracted  state  of  the  pupil,'  insensibility  of  the 
mucous  lining  and  integument  of  the  upper  eyelid,  insensi- 
bility of  the  skin  of  the  forehead  and  the  external  and  in- 
ferior parts  of  the  nose,  and  a  total  absence  of  the  sense  of 
contact  in  the  anterior  portions  of  the  mucous  membrane  of 
the  nostril. 

If  the  superior  maxillary  nerve  alone  be  affected,  the  skin 
and  mucous  lining  of  the  lower  eyelid,  the  integument  of  the 
cheek,  lower  half  of  the  nose,  and  the  corresponding  half  of 
the  upper  lip,  show  an  entire  or  partial  abolition  of  sensibility  ; 
while  the  mucous  membranes  of  the  middle  and  posterior  por- 
tions of  the  nasal  cavity,  of  the  roof  of  the  palate,  and  the  en- 
tire soft  palate  and  uvula,  are  similarly  affected.  The  teeth 
and  gums  of  the  upper  jaw  will  also  be  in  the  anaesthetic  con- 
dition. 

If  the  inferior  maxillary  nerve  be  the  seat  of  disease,  with- 
out impairment  of  the  motor  root  of  the  nerve,  the  integument 
of  the  outer  surface  of  the  ear,  above  the  auditory  canal,"  of 
the  temporal  region,  of  the  corresponding  half  of  the  lower 
lip,  and  in  front  of  the  temporo-maxillary  articulation,  will  be 
destitute  of  sensibility.  The  mucous  membrane  of  the  corre- 
sponding side  of  the  lower  lip,  tongue,  cheek,  tonsil,  and  gum 
of  the  lower  jaw  will  be  also  anaesthetic,  while  the  teeth  of  the 

'  See  investif^ations  of  Daniellsen  and  Boeck,  as  quoted  by  Rosenthal, 

'  For  effects  of  nerve  influences  on  the  pupil,  see  page  879  of  this  volume. 

•  For  researches  of  Hilton  on  this  point,  see  page  404  of  this  volume. 


TEOPHIG  EFFECTS  OF  TRIGEMINAL  PARALYSIS.       413 

corresponding  side  of  the  lower  jaw  will  likewise  be  deprived 
of  sensibility. 

If  yon  will  recall  the  points  which  were  made  in  reference 
to  the  effects  of  section  of  the  trigeminus,  you  will  be  better 
able  to  understand  why  paralysis  of  any  portion  of  this  nerve 
should  be  followed  by  symptoms  of  late  development,  due, 
apparently,  to  some  alteration  in  the  nutrition  and  reactive 
power  of  the  regions  supplied  by  the  nerve  which  is  diseased. 
You  will  remember  that  the  existence  of  certain  unnamed 
fibers,  called  '' trophic  fibers,"  was  mentioned,  whose  close 
connection  with  the  sympathetic  nerve  is  highly  probable, 
and  whose  function  seems  to  be  to  control  and  regulate  the 
blood  supply  of  the  regions  to  which  they  pass.  Now,  it  is 
clinically  observed  that  the  paralysis  of  any  of  the  three 
large  branches  of  the  trigeminus  is  followed  by  certain  ulcer- 
ative and  suppurative  processes  in  the  regions  rendered  anaes- 
thetic, and  that  these  effects  are  the  most  prominent  and 
serious  when  the  ophthalmic  nerve  is  affected. 

Landmann  and  Bell  were  the  first  observers  to  point  out 
that,  in  the  human  subject,  purulent  destruction  of  the  eye 
was  liable  to  follow  pressure  upon  the  trigeminus  from  tumors 
in  the  region  of  the  ganglion  of  Crasser;  while  Magendie 
(1824),  Bock  (1844),  Snellen  (1858),  Spencer  Watson  (1874), 
Samuel  (1860),  and  Meissner  have  done  much  to  bring  the 
results  of  defective  nutrition,  following  impairment  of  nerve 
supply,  to  professional  notice.  It  might  add  much  to  the 
interest  of  this  volume  to  enter  into  the  details  of  the  inter- 
esting experiments  and  clinical  observation,  which  have  now 
become  quite  extensive  regarding  this  subject,  but  it  will  ex- 
ceed the  scope  of  this  course  to  more  than  hastily  sketch  the 
results  obtained.  The  opinion  of  Snellen,  that  the  ulceration 
of  the  cornea  and  the  suppurative  conjunctivitis  which  fol- 
lows anaesthesia  of  the  ophthalmic  nerve  were  the  mechanical 
effects  of  the  irritation  of  dirt  which  the  conjunctiva  was  no 
longer  capable  of  perceiving,  seems  to  have  been  confirmed  by 
Watson '  and  Baerwinkel,"  who  found  that  an  artificial  cleans- 

^  "Med.  Times,"  1874.  *  "Arch.  f.  klin.  Med.,"  1874. 

29 


414  THE  CRANIAL  NERVES. 

ing  and  closure  of  the  eyelids  caused  recovery,  without  any 
effect  upon  the  nerve  condition.  It  was  apparently  also  proven 
by  Bock  and  Samuel  that  the  condition  of  anaesthesia  was  not 
necessary  to  the  development  of  these  later  processes,  resulting 
in  destruction  of  tissue,  since  the  same  results  were  observed 
when  hyperaesthesia  existed.  In  reference  to  the  course  of 
the  ''trophic  fibers"  of  the  ophthalmic  nerve,  the  researches 
of  Meissner  and  Schiff '  seem  to  locate  their  situation  in  the 
central  portion  of  the  nerve,  since  the  other  parts  seem  to 
preside  over  sensation  only.  Finally,  the  interesting  experi- 
ments of  Sinitzin,"  made  in  1871,  show  some  remarkable 
effects  of  the  removal  of  the  superior  cervical  ganglion  of  the 
sympathetic  nerve  upon  trigeminal  ophthalmia ;  since  it  was 
often  cured  when  once  started,  and  prevented  in  every  case 
where  it  was  done  before  the  trigeminus  was  divided. 

We  know,  irrespective  of  the  theories  of  its  causation, 
that  the  destruction  of  the  sensory  root  of  the  fifth  nerve  is 
liable  to  be  followed  by  destruction  of  sight,  interference 
with  the  sense  of  smell,  ulceration  of  the  nose  and  gums,  a 
tendency  to  inflammation  and  abscess  of  the  soft  tissues,  and, 
possibly,  to  gangrene. 

It  is  of  practical  importance,  however,  to  discriminate 
between  that  form  of  trigeminal  anaesthesia  dependent  upon 
central  lesions  and  that  due  to  external  pressure  or  disease. 

We  may  remember  that  the  central  form  is  usually  con- 
fined to  the  inferior  maxillary  portion  of  the  nerve ;  that  a 
previous  history  of  cerebral  disease  will  often  be  found  ;  that 
paresis  or  paralysis  of  the  muscles  of  the  face,  tongue,  jaws, 
or  limbs  will  possibly  coexist ;  and  that,  if  the  lesion  be  a 
tumor  at  the  base  of  the  cerebrum,  cephalalgia,  neumlgias  of 
special  branches  of  the  trigeminus,  and  a  simultaneous  affec- 
tion of  some  of  the  adjacent  nerves  of  the  cranium  may  be 
discovered. 

If  the  cause  is  outside  of  the  cranium  (pro\dded  it  be  not 
due  to  syphilis,  rheumatic  diathesis  or  traumatism),  we  may 
expect  to  find  evidences  of  the  previous  existence  of  abscess, 

1  " Centralbl,"  1867.  «  "Med.  Centralbl.,"  1871. 


DIAGNOSTIC  VALUE  OF  THE  FIFTH  NERVE.  415 

periostitis  of  some  of  the  osseous  canals  through  which  the 
\'arious  branches  of  the  trigeminus  pass,  or  of  local  tumors 
which  are  creating  pressure  upon  some  nerve  trunk  or  its 
terminal  filaments. 

The  motor  root  of  the  fifth  nerm  may  he  impaired  from 
the  pressure  exerted  by  meningeal  exudation,  extravasations 
of  blood,  or  tumors  within  the  cranium  ;  while  it  is  frequently 
involved  (after  the  sensory  portion  of  the  trigeminus)  during 
the  development  of  some  type  of  basilar  affection.  The  re- 
sults are  manifested  by  a  paralysis  of  the  muscles  of  mastica- 
tion upon  the  side  where  the  nerve  is  diseased,  except  the 
l)uccinator  muscle,  which  derives  its  motor  power  from  the 
facial  nerve.  The  healthy  muscles  of  the  opposite  side  tend 
to  crowd  the  lower  jaw  toward  the  affected  side  of  the  face 
(luring  mastication,  giving  a  peculiar  expression  during  the 
net  of  eating. 

DIAGNOSTIC   VALUE   OF  THE   FIFTH   NERVE. 

To  what  extent  the  distribution  of  the  fifth  nerve  is  of 
practical  value  in  diagnosis  may  be  estimated  by  the  perusal 
of  the  lectures'  of  Sir  John  Hilton  upon  the  significance  of 
pain  and  the  use  of  rest  as  its  cure.  Cases  have  been  reported 
])y  Paget,  in  his  lectures  on  surgical  pathology,  and  also  by 
Anstie,''  where  the  hair  of  the  entire  scalp  has  turned  white 
after  a  severe  attack  of  neuralgic  headache ;  and  another  is 
reported  by  Anstie,  where  the  hair  of  the  eyebrow  alone  be- 
came perfectly  blanched  from  pain  in  that  region  dependent 
upon  the  supra-orbital  nerve.  Hilton  reports  a  case  where  the 
hair  of  the  temple^  from  the  irritation  excited  in  the  dental 
l)ranches  of  the  fifth  nerve  through  a  decayed  molar  tooth, 
became  suddenly  gray  (the  temple  being  the  region  supplied 
l)y  the  auriculo-temporal  branch  of  the  same  nerve) ;  and  an- 
other where  an  obstinate  form  of  ulcer  in  the  auditory  canal, 
which  was  very  painful,  and  had  withstood  all  methods  of 
treatment,  was  cured  by  the  extraction  of  a  decayed  tooth  in 
the  upper  jaw ;  again  illustrating  the  fact  that  irritation  of 

1  "Rest  and  Pain,"  London  (Xew  York,  ISTQ).  ^  "  Lancet,"  1866. 


416  THE  CRANIAL  NERVES. 

one  brancli  (the  dental)  can  create  disease  at  the  seat  of  distri- 
bution of  another  branch  of  the  same  nerve  (the  auriculo- 
temporal). 

The  temporo-maxillary  articulation  has  often  been  known 
to  assume  a  condition  of  immobility  during  an  attack  of  ear- 
ache, and  to  be  immediately  relieved  by  the  application  of  an 
anodyne  to  the  terminal  filaments  of  the  fifth  nerve  in  the 
canal ;  thus  illustrating  the  effect  of  irritation  of  one  branch 
(the  auriculo-temporal)  upon  the  others  which  supply  the 
muscles  of  mastication,  causing  them  to  contract  and  thus  fix 
the  joint. 

Again,  a  furred  condition  of  the  lateral  half  of  the  tongue 
may  almost  be  considered  a  pathognomonic  sign  of  some 
source  of  irritation  to  the  fifth  nerve,  which  thus  manifests 
itself  in  the  peripheral  distribution  of  one  of  its  branches  (the 
gustatory  nerve).* 

Chronic  ulceration  of  the  cornea  has  also  been  reported  by 
Anstie  as  a  symptom  produced  by  some  source  of  irritation  of 
the  fifth  nerve,  far  removed  from  the  seat  of  disease. 

The  intimate  communication  of  the  internal  portions  of  the 
mouth  with  the  eye,  ear,  and  nose  often  accounts  for  many 
curious  symptoms,  which  it  would  be  difficult  to  account  for, 
did  we  not  know  that  pain  may  be  felt  at  any  branch  of  a 
nerve,  when  one  of  its  trunks  is  irritated.  I  have,  at  the 
present  time,  a  patient  under  my  care,  who  is  suffering  from 
an  obstinate  ulceration  of  the  tongue,  and  who  had,  previous 
to  his  consulting  me,  been  treated  for  an  inflammatory  condi- 
tion of  the  ear,  on  account  of  a  constant  and  severe  pain, 
which  was  considered  as  separate  and  distinct  from  the  trou- 
ble which  was,  at  the  same  time,  affecting  his  tongue.  A  sim- 
ple gargle  of  opium,  which  I  ordered  him  to  hold  for  fifteen 
minutes  in  his  mouth  at  intervals,  relieved  the  symptom  in  a 
very  short  time. 

A  case  is  reported  by  Hilton  where  an  enlarged  cervical 
gland  appeared  with  a  simultaneous  discharge  from  the  au-  \ 
ditory  canal^  and  where  the  explanation,  by  which  a  decayed  j 

'  Bransby  Cooper ;  John  Hilton.  i 


DIAGNOSTIC  VALUE  OF  THE  FIFTH  NERVE.  417 

tooth  was  diagnosed  as  tlie  cause  of  the  condition,  was  as 
follows:  The  irritated  dental  branches  of  the  fifth  nerve 
caused  an  inflammation  of  the  auditory  canal,  which  is  sup- 
plied by  another  branch  (the  auricular  of  the  auriculo-tem- 
poral)  ;  this  inflammation  was  followed  by  suppuration 
and  excoriation  of  that  canal,  and,  subsequently,  by  ab- 
sorption of  the  discharges  by  the  lymphatic  vessels,  thus 
producing  the  enlarged  gland  of  the  neck.  This  expla- 
nation may  seem  a  roundabout  way  of  reaching  a  diagnosis, 
but  the  result  of  drawing  the  tooth  proved,  in  this  case, 
how  well  anatomy  may  guide  us,  if  we  only  follow  its  teach- 
ings. 

Earache  may  not  always  be  due  to  the  fifth  nerve,  even 
when  it  is  confined  to  the  external  portion  of  the  organ,- 
since  the  second  cervical  nerve  supplies  the  lower  and  hacTc 
part  of  the  external  ear,  so  that  pain  in  that  region  should 
lead  us  also  to  look  for  some  cause  of  irritation  to  that  nerve. 

The  distribution  of  nerves  to  the  scalp,  as  shown  in  the 
figure  on  page  405,  renders  the  symptom  of  pain,  in  any  por- 
tion of  the  scalp,  one  which  may  guide  us  in  looking  for  its 
cause ;  since,  if  it  is  confined  to  the  anterior  and  lateral 
aspects  of  the  head,  the  fifth  nerve  is  probably  affected  by 
some  source  of  irritation  (and  a  reference  to  the  cut  will  tell 
you  which  branch  of  the  nerve  is  distributed  to  the  seat  of 
pain),  while,  if  confined  to  t\iQ  posterior  portion  of  the  scalp, 
the  occipital  nerves  are  affected,  and  disease  of  the  spine  may 
be  suspected,  in  the  region  of  the  first  or  second  cervical  ver- 
tebrae. 

The  distribution  of  the  fifth  nerve  to  the  conjunctiva,  both 
of  the  globe  of  the  eye  and  also  of  the  lids,  exhibits,  to  a 
wonderful  degree,  the  axiom  given  you  in  the  first  lecture  of 
the  course,  as  to  the  harmony  of  action  between  the  sensory 
nerves  of  the  skin,  the  muscles  adjacent,  and  the  joints  which 
they  move  ;  since  these  parts  stand  very  much  in  the  same 
general  relation  to  each  other,  if  the  movable  point  in  the 
eyelids  be  taken  as  a  joint,  and  the  muscles  of  the  lids  as 
those  which  move  it. 


418  THE  CRANIAL  NERVES. 

An  analogy  has  been  drawn  by  a  prominent  author* 
between  a  common  two-rooted  spinal  nerve  and  a  great 
''compound  nerve  "of  the  head,  whose  sensory  root  corre- 
sponds to  the  sensory  portion  of  the  fifth  nerve,  and  whose 
Tnotor  root  comprises  the  third,  fourth,  fifth  (its  motor 
portion),  sixth,  and  seventh  cranial  nerves,  which,  together, 
form  the  motor  root  of  this  compound  nerve.  Most  of  the 
reflex  acts  which  are  exhibited  in  the  regions  of  the  head 
and  the  upper  portion  of  the  neck  can  be  explained  by 
the  free  communication  which  exists  between  the  sensory 
root  of  this  ''compound  nerve"  and  its  different  motor 
branches. 

It  seems  useless  to  further  incorporate  such  cases,  which 
go  to  prove  that  only  by  a  thorough  familiarity  with  anat- 
omy are  we  enabled  to  explain  the  many  phenomena  which 
often  puzzle  the  practitioner ;  and  that,  if  we  will  but  use  it 
as  a  guide,  diagnosis  may  be  greatly  simplified,  and  an  easy 
remedy  often  discovered  for  the  symptoms. 

SURGICAL  ANATOMY   OF  THE   FIFTH   NERVE. 

Surgical  operations  are  often  demanded  for  the  relief  of  \ 

those  tormenting  neuralgias  which  affect  the  branches  of  the  ^ 

fifth  nerve.  i 

The  simple  division  of  a  nerve  is,  at  present,  seldom  prac-  \ 

ticed,  owing  to  the  certainty  of  prompt  reunion  of  the  nerve  ' 

divided.     Resection  of  not  less  than  two  inches  of  its  length  ^ 

is  usually  required  to  make  reunion  impossible,  or  very  re-  \ 

mote  in  point  of  time.     It  has  been  proposed  to  turn  the  pe-  i 

ripheral  extremity  of  the  nerve  backward  after  section,  or  to  \ 

interpose  muscle  or  fascia,  to  prevent  the  possibility  of  union.'  | 

Exposure  and  stretching  of  spinal  nerves  for  the  relief  of  neu-  '• 

ralgia  have  been  proposed  by  Von  Nussbaum,  but  are  not  i 

usually  practiced  upon  the  cranial  nerves.  1 

The  supra-orhital  nerve  may  be  thus  divided  : 

Pass  a  narrow  knife,  subcutaneously,  from  a  point  two  or 
three  lines  on  the  inner  side  of  the  supra-orhital  notch.,  out- 

>  John  Hilton,  "  Rest  and  Pain."  «  S.  W.  Mitchell. 


SURGICAL  ANATOMY  OF  THE  FIFTH  NERVE.  419 

ward,  until  the  point  has  passed  beyond  the  notch ;  then  turn 
the  blade  backward,  and  cut  down  to  the  bone.  To  resect 
the  nerve,  make  a  one -inch  incision  above  and  parallel  to  the 
supra-orbital  arch  ;  seize  the  cut  ends  of  the  nerve  in  the 
wound,  and  remove  it  to  the  desired  extent. ' 

To  excise  the  superior  maxillary  nerve^  a  crucial  incision 
is  made  over  the  infra-orhital  foramen^  and,  by  the  use  of  a 
small  trephine,  the  anterior  wall  of  the  antrum  is  opened  so  as 
to  include  the  foramen.  The  lower  wall  of  the  infra-orbital 
canal  is  now  broken  with  a  chisel  as  far  as  the  spheno- 
maxillary fossa,  and  the  nerve  is  then  divided  at  the  fora- 
men rotundum  with  a  pair  of  scissors  sharply  curved. 
Meckel's  ganglion  is  frequently  removed  with  the  excised 
nerve.* 

To  divide  the  inferior  dental  nerve^  the  incision  may  be 
made  within  the  mouth  or  externally.  If  the  trunk  is  to  be 
removed,  before  the  nerve  enters  the  canal  in  the  lower  jaw, 
the  external  incision  is  made  from  the  sigmoid  notch  to  the 
edge  of  the  jaw.  The  parotid  gland  is  then  turned  backward, 
and  the  lower  portion  of  the  masseter  muscle  detached.  A 
section  of  bone  is  now  removed  with  a  trephine,  and  the  dental 
artery  is  tied,  in  case  it  be  wounded  ;  the  nerve  may  then 
be  divided,  and  a  half  inch  of  it,  which  will  be  found  to  be 
exposed,  resected. 

In  the  intra-huccal  operation,  the  corner  of  the  mouth  is 
held  wide  open,  and  an  incision  one  inch  in  length  is  made 
along  the  anterior  part  of  the  ramus  of  the  jaw,  through  the 
fibers  of  the  internal  pterygoid  muscle.  This  muscle  is  then 
loosened  from  the  periosteum  by  the  finger,  where  the  nerve 
can  be  easily  felt,  at  its  entrance  into  the  dental  canal,  and 
there  divided. 

THE   GAN^GLIA   CONIS'ECTED   WITH  THE   FIFTH   NERVE. 

In  the  cut  which  illustrates  the  distribution  of  the  branches 
of  the  fifth  nerve  will  be  perceived  four  ganglionic  enlarge- 

*  J.  N.  Warren.  '  J.  R.  Wood. 


420  THE  CRANIAL  NERVES. 

ments,  exclusive  of  the  ganglion  of  Gasser,  which  are  con- 
nected with  the  nerve,  and  which  have  a  most  important 
function  as  regards  the  tissues  to  which  these  branches  are 
distributed. 

As  you  will  notice,  the  first  is  connected  with  the  ophthal- 
mic division,  and  is  situated  within  the  orbit.  It  is  called  the 
"ophthalmic  ganglion,"  from  its  attachment;  also  the  "len- 
ticular ganglion,"  from  its  shape ;  and  the  "  ciliary  ganglion," 
since  it  gives  off  the  ciliary  nerves  to  the  iris  and  the  muscle 
of  accommodation  of  vision.  Like  all  the  ganglia  of  the  sym- 
pathetic nerve,  it  has  a  motor  root^  a  sensory  root,  and  a  sym- 
pathetic root,  and  it  furnishes  branches  of  distribution  to 
neighboring  parts. 

The  second  is  called  "Meckel's  ganglion,"  after  its  discov- 
erer; and  the  "  spheno-palatine  ganglion,"  since  it  is  chiefly 
distributed  to  the  region  of  the  palate.  It  is  situated  in  the 
spheno-maxillary  fossa,  and  sends  branches  to  the  orbit, 
nose,  hard  and  soft  palate.  It  lies  in  close  relation  with  the 
superior  maxillary  nerve. 

The  third  is  called  the  "otic  ganglion."  It  lies  upon  the 
inferior  maxillary  nerve  below  the  foramen  ovale,  and  sends 
branches  to  the  two  tensor  muscles,  viz.,  the  tensor  tympani 
and  the  tensor  palati.  It  is  thus  physiologically  associated 
with  the  acts  of  hearing  and  deglutition. 

The  fourth  is  called  the  "  submaxillary  ganglion,"  since  it 
lies  above  the  submaxillary  gland.  It  is  by  means  of  the  dis- 
tribution of  the  chorda  tympani  nerve  to  this  ganglion  that 
some  physiologists  attempt  to  explain  the  apparent  effect 
which  that  nerve  has  upon  the  sense  of  taste  in  the  anterior 
two  thirds  of  the  tongue.* 

The  following  table '  will  perhaps  assist  you  in  remember- 
ing the  special  points  of  each  of  these  ganglia,  as  it  shows  the 
various  sources  of  supply  to  each,  as  weU  as  branches  of  dis- 
tribution : 

^  See  previous  portion  of  this  chapter,  where  the  gustatory  nerve  is  discussed. 
*  After  Keen. 


THE  ABDUGEN8,    OR  SIXTH  NERVE. 
THE   GANGLIA   OF  THE   FIFTH   CEAKIAL   NERVE. 


421 


Name. 

Situation. 

Sensory  root. 

Motor  root. 

Sympathetic 
root. 

Branches  of  distribution. 

OPHTHAL- 
MIC or 
CILIAEY. 

Between  the 
optic  nerve 

and  enet. 

rectus. 

5th  neeve — 

Nasal 
branch. 

3d  neeve. 

Cavernous 

PLEXUS. 

To  ciliitry  muscle  and 
iris. 

% 
< 
O 

i 

MECKELS 

or 
SPHENO- 
PALATINE. 

Spheno- 

maaillary 

fossa. 

5th  nerve— 
Spheno-pala- 
tine  branches. 

Tth  nerve, 
through  Vidi- 
an and  large 
petfosal 
branches. 

CAROTro 

PLEXUS,  bv 
means  of  Vi- 
dian nerve. 

Orbital,  nasal,  naso-paia- 
t<ne,  anterior  or  large 
palatine,  ii.iddle  or  ex- 
ternal palatine. 

Post,  or  I  Levator  palati, 
small   <  Azygos  uvulae, 

palatine    Palato-glossus. 

OTIC. 

Below  the 

foramen 

oxale. 

5th  nebve— 
Auriculo- 
temporal 
branch. 

7th  nerve, 

through  small 

petrosal. 

5th  nerve, 

through  int. 

pterygoid 

branch. 

Plexus  on  the 

MIDDLE   ME- 
NINGEAL 
ARTERY. 

To  tensor  tympani  and 
tensor  palati  muscles. 

SUBMAXIL- 
LAEV. 

Above  the 
fnihmaacil- 
lary  gland. 

5Tn  NERVE — 

Lingual  or 
gustatory 
branch. 

Tth  nerve, 
through  chor- 
da tympani 
branch. 

Plexus  on  the 

FACIAL 
ARTERY. 

To  submaxillary  gland 
and  mucous  membrane 
of  the  mouth. 

By  reference  to  the  above  table,  you  will  perceive  that  the 
sensory  root  of  each  of  the  four  ganglia  is  derived  from  the 
fifth  cranial  nerve  by  means  of  some  of  its  branches ;  that 
the  motor  root  is  derived,  in  three  cases  out  of  four,  from  the 
seventh  cranial  nerve ;  and,  finally,  that  in  every  case  is  the 
sympathetic  root  derived  from  2i  plexus  upon  some  neighbor- 
ing blood-vessel. 


THE  ABDUCENS,  OR  SIXTH  NERVE  (MOTOR  OCULI  EXTERNUS). 

The  apparent  origin  of  this  nerve  is  from  a  groove  between 
the  anterior  pyramid  of  the  medulla  oblongata  and  the  pos- 
terior border  of  the  pons  Varolii.  The  nerve  may  be  said  to 
possess  two  roots,  one  of  which  can  be  traced  into  the  pyra- 
midal body  of  the  medulla,  and  the  other  into  the  pons  Va- 
rolii itself.     This  latter  root  is  sometimes  wanting. 

Its  deep  origin  has  been  traced  by  Lockhart  Clarke  to  a 
nucleus  in  the  gray  matter  of  the  fourth  ventricle  of  the  brain, 
on  the  outer  side  of  the  locus  cceruleus. 

This  nerve  is  purely  motor  in  its  function,  and  is  distribu- 
ted to  the  external  rectus  muscle  of  the  eye. 


422 


THE  CRANIAL   NERVES. 


The  most  careful  researches  of  Vulpian  have  as  yet  failed 
to  discover  any  decussation  of  the  deep  fibers  of  this  nerve, 
and  there  would  seem  to  be  a 
physiological  explanation  for 
the  absence  of  such  an  arrange- 
ment, since  the  two  external 
recti  muscles  are  seldom  called 
into  simultaneous  action,'  and 
the  normal  movements  of  the 
eyes  are  opposed  to  such  a  po- 
sition as  would  ensue  if  they 
should  act  in  common. 

The  sixth  nerve  anasto- 
moses with  the  sympatJietic 
nerve  in  the  cavernous  sinus, 
where  it  receives  filaments  from 
both  the  carotid  plexus  and 
from  Meckel's  ganglion  ;  and  a 
few  sensory  filaments  are  said 
to  be  given  to  it  in  this  local- 


FiG.  108. — Distribution  of  the  motor  oculi 
externus.     (Ilirschfcld.) 

1,  trupk  of  the  motor  oculi  communis,  with 
its  branches  (2,  3,  4,  5,  6,  V) ;  H,  motor 
oculi  externus^  passing  to  the  external 
rectus  muscle  ;  9,  filaments  of  the  motor 
oculi  externus  anastomosing  with  the 
sympathetic  ;  10,  ciliary  nerves. 


ity  from  the  ophthalmic  branch  of  the  fifth  cranial  nerve. 

Occasionally,  this  nerve  sends  a  filament  to  the  ophthalmic 
ganglion,  and  thus  to  the  iris,  and  it  is  claimed  by  Longet 
that  this  arrangement  (which  is  an  exceptional  one)  exists  in 
those  cases  of  paralysis  of  the  motor  oculi  nerve  in  which 
there  is  no  apparent  effect  produced  upon  the  mobility  of  the 
pupil. 

This  nerve  has  no  practical  importance  to  the  diagnostician, 
save  the  one  fact  that,  in  case  it  be  paralyzed,  the  eye  will 
present  the  condition  of  internal  strabismus ;  that  the  ap- 
parent size  of  the  objects  perceived  by  the  retina  is  magni- 
fied i""  and  that  the  head  will  be  so  deflected  as  to  avoid  the 
perception  of  double  images.' 

The  explanation  of  both  of  these  effects,  as  the  result  of 

'  After  the  eyes  have  been  drawn  inward,  as  in  attempts  to  focus  near  objects,  these 
muscles  help  to  restore  the  axes  of  vision  to  a  state  of  parallelism. 

*  For  explanation  of  this  symptom,  the  reader  is  referred  to  page  889  of  this  volume. 
'  See  page  886  of  this  volume. 


THE  FACIAL,    OR  SEVENTH  NERVE.  423 

paresis  of  certain  ocular  muscles,  has  already  been  given  in 
the  previous  lecture  upon  the  third  cranial  nerve,  and  need 
not  be  again  repeated.  It  should  not  be  forgotten,  however, 
that  internal  strabismus  is  not  always  due  to  paralysis  of  the 
external  rectus  muscle,  but  may  indicate  a  condition  of  con- 
genital or  acquired  hyperopia,  causing  a  weakness  of  the  ex- 
ternal rectus  muscle. 


THE  FACIAL,   OR  SEVENTH  NERVE. 

This  nerve  has  its  apparent  origin  from  a  groove  between 
the  olivary  and  restiform  bodies  of  the  medulla  oblongata, 
and,  like  the  three  preceding,  has  its  chief  origin  in  a  gray 
nucleus  in  the  floor  of  the  fourth  ventricle,  in  the  upper  half 
of  that  space  near  to  the  postero-median  fissure.'  The  fila- 
ments of  origin,  within  the  substance  of  the  medulla  oblongata, 
may  be  traced  as  a  fan-like  expansion  upon  the  floor  of  the 
fourth  ventricle,  some  of  which  terminate  in  the  gray  nucleus, 
above  described,  of  the  same  side  as  that  on  which  the  nerve 
escapes,  while  other  fibers  may  be  seen  to  decussate^  thus 
passing  to  the  nucleus  of  the  opposite  side.  No  filaments 
have  as  yet  been  satisfactorily  traced  upward  beyond  the 
limits  of  the  medulla.'*  This  nerve  accompanies  the  nerve  of 
hearing  throughout  the  whole  length  of  the  internal  auditory 
canal,  and  there  communicates  with  it  by  a  few  filaments.  It 
then  enters  a  curved  canal  within  the  temporal  bone,  called 
the  aqueduct  of  Fallopius^  where  it  gives  off  the  three  petro- 
sal nerves  and  the  chorda  tympani  branch,  whose  physiologi- 
cal action  has  been  already  considered  in  connection  with  the 
fifth  nerve.  From  this  canal,  it  escapes  through  the  stylo- 
mastoid foramen^  having,  before  its  exit,  given  a  tympanic 

'  Lockhart  Clarke.  An  accessory  portion  of  this  nerve— the  '*  nerve  of  Wrisberg  "— 
conveys  fibers  to  it,  whose  deep  origin  may  be  traced  to  the  lateral  column  of  the  cord. 
Its  importance  is  now  being  extensively  discussed,  as  having  a  connection  with  the  chorda 
tympani  nerve.     An  inferior  facial  nucleus  exists  in  the  pons. 

^  The  deep  origin  of  the  fibers  of  the  facial  nerve  seems  to  have  some  connection  with 
the  upper  portions  of  the  encephalon  (as  shown  by  the  clinical  facts  mentioned  in  previous 
pages,  when  discussing  "  crossed  paralysis  ") ;  the  little  that  is  positively  known  concern- 
ing  the  course  and  termination  of  these  fibers  has  been  discussed  already. 


424 


THE  CRANIAL  NERVES. 


branch  to  the  ear.'  In  the  region  of  the  stylo-mastoid  fora- 
men, it  communicates  with  five  nerves^  namely,  the  great 
auricular  (a  branch  of  the  cervical  plexus),  the  auriculo-tem- 


FiG.  109. — Superficial  branches  of  the  facial  and  the  fifth.     (Hirschfeld.) 

1,  trunk  of  the  facial ;  2,  posterior  auricular  nerve  ;  3,  branch  which  it  receives  from  the 
cervical  plexus  ;  4,  occipital  branch  ;  5,  6,  branches  to  the  muscles  of  the  ear  ;  7,  digas- 
tric branches  ;  8,  branch  to  tJie  siylo-hyoid  muscle ;  9,  superior  terminal  branch  ;  10, 
temporal  branches  ;  11,  frontal  branches  ;  12,  brancJies  to  the  orbicularis  palpebrarum  ; 
13,  nasal,  or  suborbital  brandies  ;  14,  buccal  branches  ;  15,  inferior  teryninal  brancJi  ; 
16,  mental  branches;  11,  cervical  branches;  18,  superficial  temporal  nerve  (branch 
of  the  fifth);  19,  20,  frontal  nerves  (branches  of  the  fifth);  21,  22,  23,  24,  25,  26, 
27,  branches  of  the  fifth  ;  28,  29,  30,  31,  82,  branches  of  the  cervical  nerves. 

poral  (a  branch  of  the  fifth  nerve),  the  pneumogastric,  the 

glosso-pharyngeal,  and  the  carotid  plexus  of  the  sympathetic  ; 

and,  subsequently,  it  divides  and  is  distributed  to  the  muscles. 

The  facial  is  the  great  motor  nerve  of  the  muscles  of  the 


*  Occasionally  also  the  filament  of  eommunicalion  to  the  pneumogastric  nerve. 


DISTRIBUTION  OF  FACIAL  NERVE.  425 

face;  hence  the  nerve  of  expression.'    It  supplies,  in  addi- 
tion to  the  facial  muscles,  the  muscles  of  the  external  ear ; 


Fig.  110. — A  diagram  of  the  branches  of  the  facial  nerve. 

1,  main  trunk  of  nerve  in  internal  auditory  canal ;  2,  branches  of  communication  with 
AUDITORY  NERVE ;  8,  orificc  of  aqueduct  of  Fallopius ;  4,  large  'petrosal  nerve ;  5, 
small  petrosal  nerve  ;  6,  external  petrosal  nerve  ;  7,  filaments  to  the  laxator  tympani 
muscle;  8,  chorda  tympani  new q  \  9,  stylo-mastoid  foramen ;  \0^ posterior  auricular 
nerve  ;  11,  filament  supplying  the  stylohyoid  and  digastric  muscles ;  12,  the  temporo- 
FACiAL  division  of  the  nerve  ;  13,  the  temporal  branches  ;  14,  the  malar  branches  ; 
15,  the  infra-orbital  branches;  16,  the  buccal  branches;  17,  the  supra-maxillary 
branches;  18,  the  infra-maxillary  branches;  19,  the  cervico-facial  division;  20, 
^^ intumescentia  ganglioformis''^ — the  seat  of  origin  of  the  petrosal  nerves. 

three  muscles  of  the  neck,  namely,  the  stylo-hyoid,  posterior 
belly  of  the  digastric,  and  the  platysma  ;  one  muscle  of  the 
middle  ear,  the  stapedius ;  and  one  muscle  of  the  palate,  the 
levator  palati.''  By  means  of  the  chorda  tympani  branch, 
it  controls  the  secretion  of  the  parotid  and  submaxillary 
glands,  and,  possibly,  the  sense  of  taste."    By  the  large  pe- 

'  Sir  Charles  Bell. 

^  Schiff,  1851 ;  Bernard.  Possibly  also  some  other  muscles,  by  means  of  the  lingual 
branch,  described  by  Hirschberg. 

3  Sappey ;  Hirschfeld;  A.  Flint,  Jr. ;  J.  C.  Dalton.  The  fibers  of  the  chorda  tympani 
nerve,  by  some  of  the  later  authorities,  are  said  to  arise  from  an  intermediate  nerve 
formed  by  a  branch  from  both  the  seventh  and  eighth  cranial  nerves,  and  called  the 
"  portio  intermedia  "  or  "  nerve  of  Wrisberg." 


426  THE  CRANIAL  NERVES, 

trosal  branch,  the  levator  palati  and  azygos  nvnlse  are  sup- 
plied ;  and,  by  the  small  petrosal  branch,  the  tensor  tym- 
pani  and  tensor  palati  muscles  are  furnished  with  motor 
power. 

Several  interesting  articles  have  lately  appeared  upon  the 
subject. ' 

It  is  claimed  by  Yulpian  that  the  facial  nerve  also  con- 
tains vaso-motor  fibers^  which  are  distributed  to  the  vessels  of 
the  tongue  and  side  of  the  face. 

The  effects  of  paralysis  of  the  facial  nerve  were  first 
brought  to  professional  notice  by  Sir  Charles  Bell,  who  di- 
vided it  for  facial  neuralgia,  and  the  characteristic  deformity 
which  resulted  is  still  known  under  the  name  of  '^  Bell's  pa- 
ralysis." In  this  condition,  the  affected  side  loses  its  normal 
expression,  and  becomes  abnormally  smooth  on  account  of 
the  obliteration  of  the  normal  lines  and  wrinkles,  due  to  the 
action  of  the  antagonistic  muscles  on  the  healthy  side."  The 
patient  loses  all  power  of  closing  the  eye  of  the  affected  side 
even  in  sleep,  since  the  orbicularis  palpebrarum  muscle  is 
paralyzed ;  the  mouth  is  no  longer  symmetrical,  since  it  is 
drawn  toward  the  healthy  side ;  the  saliva  i^  with  difficulty 
retained ;  and  the  act  of  whistling  becomes  an  impossibility, 
as  the  lips  can  not  be  systematically  governed.  This  condi- 
tion may  be  produced  by  exposure  to  severe  cold,  as  in  sleigh- 
riding  ;  by  abscess  or  tumors  of  the  parotid  region,  as  the 
result  of  the  pressure  created  ;  by  diseases  of  the  ear  or  inju- 
ries to  the  temporal  bone,  which  impede  the  free  action  of 
the  nerve ;  and  by  cranial  lesions.  It  is  particularly  impor- 
tant that  the  surgeon  should  familiarize  himself,  not  only 
with  the  situation  and  course  of  the  main  trunk  of  this 
nerve,  but  also  with  the  course  of  its  branches,  previous  to 
performing  operations  about  the  face,  or  in  the  vicinity  of 
the  mastoid  process,  and  in  the  upper  portions  of  the 
neck. 

1  Vulpian,  "Lancet,"  1878;  H.  R.  Bigelow,  "Brain,"  1876;  E.  C.  Spitzka  "Medical 
Record,"  1880. 

'  Ilcnce  the  aptness  of  the  remark  by  Romberg,  as  quoted  by  Hammond,  that  "  there 
is  no  better  cosmetic  for  elderly  ladies  than  facial  paralysis." 


DISTRIBUTION  OF  FACIAL  NERVE. 


427 


The  distribution  of  this  nerve  to  the  muscles  of  the  palate 
and  to  the  stylo-hyoid  explains  the  impairment  of  deglutition 
when  the  facial  nerve  is  paralyzed  ;  while  the  filament  to  the 
stapedius  muscle  may  create  modifications  in  the  sense  of 
hearing  under  similar  conditions. '  * 


Fig.  111. — BeWs paralysis.    (Modified  from  Corfe.) 

The  following  tabulated  arrangement  of  the  branches  of 
the  seventh  nerve  ^  will  possibly  prove  of  service  to  you  as  an 
aid  to  memory  during  your  student  life ;  and,  as  a  guide  for 
reference  or  review  in  your  professional  labors,  such  tables 
are  always  of  value  : 


'  The  tensor  tympani  muscle  may  also  be  involved. 

2  Copied  from  "  The  Essentials  of  Anatomy"  :  Darling  and  Ranney,  New  York,  1880. 


428 


THE  CRANIAL  NERVES. 


TABLE   OF  THE   BRANCHES   OF  THE   FACIAL   NERVE. 


I 

PS 

o 

< 

W 

Eh 


Branches  of 
eommunication. 


Branches  of 
distribution. 


In  the  auditory  canal. 


In  the  aqueduct  of  Fallopius. 


At  its  exit  from  the  stylo-mas- 
toid  forameri^  with  the  fol- 
lowing nerves : 

On  the  face. 


Branch  to  auditory  nerve. 

Large   petrosal    (to    Meckel's 
ganglion). 

Small  petrosal  (to  otic  gangl'n). 

External  petrosal  (to  meningeal 
plexus). 

Tympanic  branch. 

Great  auricular, 

Auriculo-temporal. 
^  Pneumogastric' 

Glosso-pharyngeal. 
[  Carotid  plexus. 

Branches  to  fifth  cranial  nerve. 


inic  nerve. 
tympatd  nerve. 


In  the  aqueduct  of  Fallopius.     <   Chorda 

r  Posterior  auricular  nerve. 
Near    the   styh-mastoid  fora-  J  Diagastric  branch. 
men.  j  Stylo-hyoid  branch. 

[  Lingual  branch? 
On  the  face.  \  Temporo-facial  nerve, 

vfu  uu^;  io-vAj  ^  Cervico-facial  nerve. 


If  you  will  look  at  this  diagrammatic  drawing  (Fig.  63), 
you  will  perceive  how  simple  is  the  arrangement  of  the 
branches  of  communication  between  the  facial  nerve  and  the 
fifth  cranial  nerve  and  its  ganglia.  While  the  drawing  is 
intended  to  be  purely  schematic,  still  it  also  illustrates  some 
of  the  anatomical  points  pertaining  to  the  course  and  forma- 
tion of  the  Vidian  nerve^  as  well  as  the  relations  of  the  chor- 
da tympani  nerve  to  the  membrana  tympanic  as  it  passes 
through  the  middle  ear  to  reach  the  canal  of  Huguier. 

There  is  a  practical  point  pertaining  to  the  deep  origin  of 
the  fibers  of  the  facial  nerve,  which  may  often  be  of  value  in 
determining  the  seat  of  pathological  lesions  within  the  sub- 
stance of  the  brain.  In  hemiplegia,  especially  in  that  variety 
which  is  due  to  haemorrhage,  the  face  is  sometimes  affected 
upon  the  same  side  as  the  body  and  sometimes  upon  the  oppo- 
site side,  thus  being  impaired,  respectively,  either  upon  the 
side  opposite  to  the  cerebral  lesion  or  upon  the  same  side  as 
the  lesion.     To  explain  these  phenomena  theoretically,  we 

'  This  communicating  filament  is  given  off  in  the  aqueduct  of  Fallopius  as  often  as  at 
the  stylo-mastoid  foramen, 

'  Described  by  Hirschberg,  Supplies  the  stylo-glossua  and  palato-glossus  muscles  and 
the  tongue. 


CROSSED  FACIAL  PARALYSIS. 


429 


must  suppose  that  the  facial  nerve  fibers  are  affected  by  the 
lesion  within  the  brain  before  they  decussate  (following  them 
from  within  outward),  in  case  the  face  is  paralyzed  on  the 
same  side  as  the  lesion  ;  and  that  the  decussating  fibers  are 


Fig.  112.—^  diagram  to  show  the  relations  between  the  facial  nerve  and  some  portions  of  the 

fifth  nei've. 

A,  Gasserian  ganglion ;  B,  ophthalmic  nerve ;  C,  superior  maxillary  nerve ;  D,  inferior 
maxillary  nerve  (sensory  portion) ;  E,  inferior  maxillary  nerve  (motor  portion) ;  M, 
Meckel's  ganglion;  \^  facial  nerve,  entering  the  aqveduet  of  Fallopitis ;  2,  inlumes- 
ceniia  ganglioformis  (an  enlargement  on  the  nerve) ;  3,  facial  nerve,  following  the 
curve  of  the  aqueduct  of  Fallopius ;  4,  facial  nei-ve,  escaping  from  stylo-mastoid  fora- 
men ;  5,  large  petrosal  branch,  joining  carotid  filament  11  to  form  the  Vidian  nerve, 
and  entering  the  Vidian  canal ;  6,  small  petrosal  branch,  going  to  "  otic  ganglion  "  10 ; 
7,  chorda  tympani  nerve,  escaping  from  the  canal  of  Huguier  after  winding  over  the 
upper  border  of  drum  membrane  of  ear,  9 ;  8,  gustatory  nei've,  joining  with  the  chorda 
tympani  nerve;  9,  external  drum  membrane  of  the  ear;  10,  otic  ganglion;  11,  f la- 
ment from  carotid  plexus  to  form  the  Vidian  nerve ;  1 2,  the  iter  chordae  posterius,  ad- 
mitting the  chorda  tympani  nerve  into  the  cavity  of  the  middle  ear. 


pressed  upon  or  destroyed  by  the  lesion,  in  case  the  face  be 
affected  on  the  same  side  as  the  body. 

Now,  it  has  been  observed  as  a  pathological  fact,  that 
when  a  lesion  involves  parts  of  the  encephalon  anterior  to  the 
pons  Varolii,  the  phenomena  dependent  upon  paralysis  of  the 
facial  nerve  are  perceived  on  the  same  side  as  the  hemiplegia ; 
while,  if  the  lesion  be  situated  either  in  the  lower  part '  of  the 
pons  Varolii  or  below  it,  the  face  is  paralyzed  on  the  same 
side  as  the  lesion,  or  on  the  side  opposite  to  the  hemiplegia. 

^  Gubler  has  shown  that  the  facial  nerve  is  not  paralyzed  upon  the  same  side  as  the 
lesion,  if  the  injury  to  the  pons  Varolii  be  anterior  to  the  imaginary  line  drawn  through 
the  points  of  escape  of  the  trigemini. 
30 


430  TEE  CRANIAL  NERVES.  \ 

j 

For  this  reason,  the  occurrence  of  crossed  paralysis  of  the! 
facial  nerve  *  and  body  type  has  been  received  as  a  most  posi- ! 
tive  indication  of  a  lesion  situated  upon  the  side  of  the  brain  \ 
corresponding  to  the  facial  paralysis,  and  either  within  the! 
substance  of  the  pons  Varolii  or  in  parts  of  the  encephalonj 
posterior  to  it.  Such  clinical  facts  as  these  seem  positively  to  j 
indicate  that  some  of  the  deep  fibers  of  the  facial  nerve  pass! 
upward  into  the  cerebrum^  and  that  the  decussation  of  the; 
filaments  of  origin  vrithin  the  floor  of  the  fourth  ventricle  is  of; 
little  physiological  importance  compared  to  these  other  fibers ;  I 
but,  unfortunately,  no  anatomical  investigations  have,  so  far,  j 
discovered  fibers  of  this  nerve  v^^hich  could  be  clearly  demon- 
strated as  passing  upward  beyond  the  pons  Varolii. 

It.  has  been  often  noticed  by  different  observers  that,  in: 
case  the  facial  nerve  was  paralyzed,  the  uvula  and  soft palate\ 
were  affected  and  drawn  toward  the  healthy  side  by  the  an-i 
tagonistic  muscles,  whose  motor  power  remained  unimpaired.  | 
Later  investigation  has  shown,  however,  that  this  affection  of! 
the  palate  only  occurs  in  those  cases  of  paralysis  due  to  im-j 
pairment  of  the  facial  nerve  within  the  aqueduct  of  Fallopius^ . 
or  from  some  cranial  lesion  which  affects  its  filaments  of 
origin.'' 

The  experiments  of  Bernard  seem  to  demonstrate  that  the: 
facial  nerve^  and  not  the  glosso-pharyngeal  alone,  is  con-: 
nected  with  movements  of  the  velum  palati^  but  not  with  the  j 
movements  of  the  pillars  of  the  fauces.  The  construction  of' 
the  small  petrosal  branch,  however,  being  composed  partly  of  • 
fibers  derived  from  the  glosso-pharyngeal  nerve,  may  still! 
justify  a  doubt  upon  this  point.  \ 

Hirschfeld  describes  a  small  filament,  which  the  facial] 
nerve  gives  off  soon  after  it  emerges  from  the  stylo-mastoid ; 
foramen,  ''the  Ungual  hranch^^^  which  is  distributed  to  thej 
tongue  and  to  the  stylo-glossus  and  palato-glossus  muscles,  i 

'  A  term  used  to  cover  those  forms  of  paralysis  where  the  face  is  paralyzed  on  the  ■; 
side  opposite  to  the  side  of  the  body  aifected.  i 

*  The  petrosal  nerves,  which  carry  the  motor  fibers  to  these  muscles,  must  be  impaired," 
to  cause  any  deflection  of  tlie  palate.  \ 

^  See  table  on  page  428.  ; 


COMMUNICATIONS  OF  FACIAL  NERVE.  431 

This  may  possibly  explain  tlie  observation  of  Bernard :  that 
paralysis  of  the  facial  nerve,  after  section,  produces  a  devia- 
tion of  the  tip  of  the  tongue  ;  and  the  same  effect  has  been,  at 
different  times,  recorded  as  the  result  of  paralysis  of  the  facial 
nerve  from  intra-cranial  causes. 

BBANCHES    OF   COMMUKICATIOJ^   OF   THE   FACIAL   KEEVE. 

Some  of  the  branches  of  communication  which  are  given 
off  by  the  facial  nerve,  to  join  with  other  nerves,  or  to  be  dis- 
tributed to  ganglia,  are  of  physiological  importance.  Thus 
the  levator  palati  and  the  azygos  uvulce  muscles  derive  their 
motor  power  from  the  large  petrosal  branch  after  it  enters 
Meckel's  ganglion;'  while  the  palato-glossus  and  palato- 
pJiaryngeus  muscles  probably  derived  their  motor  power 


Fig.  113. — Choi'da  tympani  nerve.    (Hirschfeld.) 

1,  2,  3,  4,  facial  nerve  passing  through  the  aqueductus  Fallopii ;  5,  ganglioform  enlarge- 
ment ;  6,  great  petrosal  nerve ;  7,  spheno-palatine  ganglion  ;  8,  small  petrosal  nerve ; 
9,  chorda  tympani;  10,  11,  12,  13,  various  branches  of  the  facial;  14,  14, 15,  glosso- 
pharyngeal nerve. 

from  the  communicating  filament  between  the  facial  and  the 
glosso-pharyngeal  nerves,  as  shown  by  Longet.  This  distribu- 
tion explains,  in  part,  why  more  or  less  difficulty  is  perceived 
in  deglutition  after  division  or  paralysis  of  the  facial  nerve, 
and  still  more  clearly  why  the  pronunciation  of  certain  words 
[becomes  impaired,  and  the  expulsion  of  mucus  from  the  back 

^  Gray,  Quain,  Sappey,  and  others. 


432 


THE  CRANIAL  NERVES. 


portion  of  the  moutli  and  from  the  pharynx  is  an  act  of 
extreme  difficulty. 

The  communication  of  the  cervical  plexus  with  the  poste- 
rior auricular  branch  of  the  facial  affords  sensory  filaments 
to  the  parts  over  the  muscles  which  that  nerve  supplies. 

The  filament  of  communication  between  the  facial  and  the 
auditory  nerves  enables  the  muscle  of  the  middle  ear  supplied 
by  the  facial '  to  act  in  harmony  with  the  acoustic  apparatus  ; 
while  the  communication  between  the  fifth  nerve  and  the 
facial  enables  the  latter  to  follow  that  general  axiom'  of 
nerve  distribution  by  which  the  skin  over  the  insertion  of 


Fig.  114. — A  diagram  to  show  the  course  of  tlic  large  and  small  petrosal  nerves  and  t1ie\ 

Vidian  nerves.  \ 

A,  otic  ganglion  ;  B,  Meckel's  ganglion ;  C,  petrous  portion  of  the  temporal  bone  ;  D,  pe- 1 
trovs  portion  of  the  temporal  bone  (its  apex  corresponding  to  the  carotid  canal  at  | 
the  base  of  the  skull) ;  E,  petrous  portion  of  the  temporal  bone  (its  base  correspond-  \ 
ing  to  the  external  auditory  meatus) ;  F,  petrous  portion  of  the  temporal  bone  (its  I 
superior  border,  separating  the  middle  and  posterior  fossae  of  the  skull);  1,  the  )i 
facial  nerve  entering  the  petrous  portion  of  the  temporal  bone  by  means  of  the  "  me-  * 
atus  auditorius  iniernus  "  /  2,  the  facial  nerve  following  the  curve  of  the  "  aqueduct  { 
of  Fallopius  " ;  3,  the  facial  nerve  escaping  from  the  temporal  bone  by  means  of  the  f 
"  stylo-mastoid  foramen  " ;  4,  the  large  petrosal  nerve^  escaping  into  the  cavity  of  the  \ 
cranium  by  means  of  the  "  hiatus  Fallopii " ;  5,  the  small  petrosal  nerve,  escaping  into 
the  cavity  of  the  cranium  by  a  foramen  of  its  own ;  6,  the  ^^ foramen  basis  ci'anii^^ 
affording  passage  for  the  large  petrosal  nerve  out  of  the  cranium  ;  7,  the  "  foramen 
ovale,"  affording  passage  for  the  small  petrosal  nerve  out  of  the  cranium,  and  thus 
to  the  otic  ganglion  ;  8,  a  filament  from  the  carotid  plexus  of  the  sympathetic  nerve, 
joining  the  large  petrosal  nerve  to  form  the  Vidian  nerve  ;  9,  the  Vidian  canal^  trans-' 
mitting  the  Vidian  nerve  to  MeckeVs  ganglion,  B;  10,  the  Vidian  nerve. 


muscles  is  supplied  by  the  same  nerve  as  the  muscles  them- 
selves. 

The  communication  between  the  facial  nerve  and    the 


'  The  stapedius.       '  Hilton,  "Rest  and  Pain."    See  also  page  13  of  this  volume. 


< 


COMMUNICATIONS  OF  FACIAL  NERVE.  433 

pneumogastric  might  at  first  seem,  to  the  casual  reader,  one 
of  accident,  rather  than  of  design,  on  the  part  of  the  Creator  ; 
but,  when  we  consider  how  intimately  the  respiratory  func- 
tions and  the  movements  of  the  face  are  associated  with  each 
other,  the  design  at  once  becomes  evident.  Paralysis  of  the 
muscles  which  dilate  the  nostrils  has  been  shown  to  have  a 
marked  effect  upon  respiration  through  the  nostril ;  and,  in 
the  horse,  which  can  only  breathe  through  the  nose,  the  effect 
of  division  of  both  of  the  facial  nerves  is  to  produce  death 
from  suffocation,  since  the  nostrils  collapse.  It  was  this 
synchronism  between  the  movements  of  the  nostrils  and  the 
respiratory  act  that  first  led  Sir  Charles  Bell '  to  regard  the 
facial  nerve  as  the  one  which  presided  over  the  function  of 
respiration,  and  is  still  often  called  one  of  the  "respiratory 
nerves  of  Bell.  ^'^ 

A  case  is  reported  by  this  famous  investigator  where  a 
patient,  afflicted  with  unilateral  facial  paralysis,  was  obliged 
to  lie  upon  the  sound  side,  and  to  hold  the  paralyzed  nostril 
open  with  the  fingers,  in  order  to  breathe  with  comfort.' 

The  distribution  of  the  facial  nerve  to  the  muscles  of  the 
nose  creates  an  impairment  of  the  sense  of  smell,^  when  that 
nerve  is  injured,  since  the  free  entrance  of  air  is  interfered 
with.  The  act  of  sniffing,  which  requires  for  its  complete 
performance  a  dilated  nostril,  is  rendered  almost  if  not  quite 
impossible,  and  thus  a  contact  of  odoriferous  substances  with 
the  mucous  membrane  of  the  upper  nasal  chambers  is  me- 
chanically interfered  with,  and  acute  perception  of  smell  em- 
barrassed. 

BRANCHES   OF   DISTRIBUTION   OF  THE   FACIAL   NERVE. 

The  motor  branches  of  the  facial  to  the  muscles  of  the  ear 
are  of  more  importance  in  animals  than  in  man,  since  the  ear 
in  the  animal  becomes  capable  of  perceiving  sound  with  acute- 
ness  only  by  a  change  in  its  relative  position  to  the  head. 

The  stylo-hyoid  and  the  posterior  belly  of  the  digastric 
muscles  exhibit  again  the  influence  of  the  facial  nerve  upon 

^  "  Lectures  on  the  Nerves."  2  Qp^  cit.  ^  A.  Flint,  Jr.,  op.  cii. 


i 

434  TEE  CRANIAL  RERVES.  \ 

the  act  of  deglutition  ;  and  the  same  remark  will  apply  to  the  < 
stylo-glossus  muscle.  ^ 

When  the  facial  nerve  has  passed  through  the  parotid  i 
gland,  the  two  branches  distributed  to  the  face,  viz.,  the  tern-  i 
porO'facial  and  the  cermeo-facial^  become  not  only  motor  in  ; 
their  function,  but  are  also  supplied  with  sensory  filaments  ! 
from  their  communication  with  other  nerves  ;  so  that  some  of  ' 
their  terminal  filaments  ar^  distributed  to  the  integument  of  . 
the  face,  as  well  as  those  derived  from  W\q  fifth  cranial  nerve^  ■- 
which  would  not  be  the  case  were  the  nerve  not  so  supplied  \ 
with  sensory  nerve  fibers.  j 

The  filament  of  the  facial  nerve  which  supplies  theplatys-  i 
ma  muscle  affords  a  beautiful  example  of  the  fact  that  the  ] 
nervous  supply  of  the  general  muscular  system,  if  carefully  | 
studied,  constantly  teaches  us  points  of  great  physiological  i 
value  as  to  the  function  of  individual  muscles,  since,  in  the  j 
expression  of  melancJioly^^  and  in  the  typical  countenance  of  \ 
thoracic  and  abdominal  diseases,"  the  platysma  muscle  plays  a  1 
most  important  part,  and  is  therefore  supplied  by  the  nerve 
of  expression. 

Again,  the  muscles  of  the  region  of  the  mouth  are  impor-  ' 
tant  agents  in  the  prehension  of  food  (especially  so  in  animals,  j 
who  often  can  not  eat  when  the  lips  are  paralyzed),  and  should  I 
properly  be,  in  some  way,  connected  with  the  muscles  of  mas-  j 
tication  (chiefly  supplied  by  the  fifth  nerve),  and  those  ofi 
deglutition  (supplied  by  the  facial  and  the  glosso-pharyngeal  ;i 
nerves) ;  hence,  the  facial  nerve  is  afforded  communicating  j 
branches  with  both  Xh^ fifth  and  the  glosso-pharyngeal  nerv^es.  j 

One  of  the  muscles  of  the  face,  the  buccinator^  which  is  \ 
supplied  exclusively  by  the  facial  nerve,  plays  a  most  impor-  [ 
tant  part  in  mastication  as  well  as  in  expression  ;  hence,  when  j 
the  facial  nerve  is  paralyzed,  the  cheek  can  no  longer  force  J 
the  food  between  the  teeth,  and  a  tendency  toward  accumula-  , 
tion  of  food  within  the  cheek  of  the  affected  side  becomes  so  \ 

'  Carpenter,  op.  cit.  1 

'  Sir  Charles  Bell,  "  Anatomy  of  Expression."    See,  also,  article  by  the  author,  "  The   ^ 

Human  Face ;  its  Modifications  in  Health  and  Disease,  etc.,"  "  New  York  Med.  Jour.,"    : 

September,  1880.  A 


PHYSIOLOGY  OF  THE  FACIAL  NERVE.  435 

distressing  to  the  patient  that  the  fingers  are  frequently  em- 
ployed, during  attempts  at  mastication  of  the  bolus,  to  force 
the  food  between  the  jaws  by  pressure  upon  the  external  por- 
tion of  the  face.' 

The  value  of  this  muscle  in  expression  is  made  manifest  in 
those  acts  where  the  cheek  is  either  inflated  with  air,  or  where 
it  is  drawn  inward,  thus  indicating  the  states  of  emacia- 
tion or  extreme  hunger.  Much  of  the  success  of  a  comedian 
often  depends  upon  the  control  which  he  possesses  over  the 
buccinator  muscle.  When  the  facial  nerve  upon  both  sides  is 
paralyzed,  mastication  is  almost  as  much  impaired  (on  account 
of  the  buccinator  muscles)  as  if  the  inferior  maxillary  nerve 
was  destroyed. 

The  flaccidity  of  the  buccinator  muscle  in  **  Bell's  paraly- 
sis "  accounts  for  the  peculiar  puffing  movement  of  the  cheek 
which  accompanies  each  act  of  expiration,  giving  to  the  face 
an  appearance  similar  to  that  noticed  when  puffing  of  a  pipe 
is  attempted  ;  while,  in  those  rare  cases  where  the  facial  nerve 
is  paralyzed  upon  both  sides,  the  face  assumes  a  condition 
which  is  remarkable  for  the  entire  absence  of  expression,  and 
which  can  only  be  compared  to  the  effect  of  covering  it  with  a 
mask. 

Many  of  the  muscles  of  the  face  are  of  value  as  guides  in 
diagnosis,  since,  in  certain  types  of  disease,  some  parts  of 
the  face  are  more  affected  than  others."  This  subject,  how- 
ever, is  too  complicated  to  be  hastily  reviewed,  and  it  has  suffi- 
cient value  to  merit  its  special  consideration. 

It  may  be  perceived,  by  reference  to  the  diagrammatic  rep- 
resentation of  the  branches  of  the  facial  nerve,  that  the  tern- 
poro facial  branch  animates  all  of  the  muscles  of  the  upper 
part  of  the  face,  while  the  cervicofacial  branch  supplies  the 
lower  region  of  the  face  and  portions  of  the  neck."  This  ex- 
plains why,  after  the  temporofacial  branch  has  been  divided, 

*  A.  Flint,  Jr.,  op.  cit. 

2  See  article  by  the  author  on  "  The  Iluman  Face ;  its  Modifications  in  Health  and 
Disease,  and  its  Value  as  a  Guide  in  Diagnosis:"  "New  York  Med.  Jour.,"  December, 
1880. 

^  See  page  425  of  this  volume. 


436  THE  CRANIAL  NERVES. 

as  has  occurred  in  operations  upon  the  cheek,  the  eye  stands 
wide  open  even  during  sleep ;  the  lower  lid  becomes  everted 
from  traction  of  the  parts  below,  and  also  from  the  effect  of 
gravity ;  the  occipito-frontalis  and  corrugator  supercilii  can 
no  longer  make  either  transverse  or  perpendicular  wrinkles 
upon  the  forehead  ;  and  the  upper  portion  of  the  face  is  ab- 
normally smooth  and  passive,  while  the  lower  portion  pre- 
serves all  its  normal  power  of  movement. 

Should  the  cervico-facial  branch  become  alone  impaired, 
the  power  of  prehension  of  food  by  the  lips  is  arrested,  the 
action  of  the  buccinator  in  mastication  is  stopped,  and  that 
process  is  proportionately  interfered  with  ;  the  digastric  and 
stylo-hyoid  muscles  are,  however,  not  paralyzed,  since  the 
special  branches  to  those  muscles  are  given  off  above  the  ori- 
gin of  this  branch,  and  thus  deglutition  is  not  embarrassed. 

CLINICAL  POINTS   AFFORDED   BY  THE   FACIAL   NERVE. 

The  diseases  which  affect  the  facial  nerve  may  produce 
the  different  varieties  of  facial  spasm  and  paralysis ;  the 
former  being  the  result  of  some  lesion  which  creates  simply 
irritation,  while  the  latter  indicates  some  existing  pressure  or 
degeneration,  which  impedes  the  free  action  of  the  nerve. 

SPASM   OF  THE   MUSCLES  OF  THE   FACE. 

In  a  class  of  cases,  by  no  means  infrequent,  facial  spasm  is 
perceived,  to  a  greater  or  less  degree,  as  the  result  of  some 
cause  of  irritation  to  the  nerve  filaments  of  the  trunk  of  the 
facial  nerve,  or  to  some  of  its  branches.  These  mimic  spasms, 
or  "  convulsive  tic,"  are  dependent  upon  an  hereditary  ten- 
dency, in  some  instances ;  since  reported  cases  exist  where 
the  second  generation,  and  even  the  third,  has  manifested  the 
symptoms  of  facial  spasm.  We  also  meet  this  condition  as  an 
accompaniment  of  epilepsy,  eclampsia,  hysteria,  tetanus,  and 
chorea ;  again,  in  certain  mental  diseases,  where  the  brain  or 
its  investing  membranes  are  affected  ;  and,  finally,  we  see  it 
developed  under  extraordinary  periods  of  excitement. 

Cases  are  on  record  where  simple  exposure,  wounds  of  the 


BELUS  PARALYSIS.  437 

face,  and  pressure  upon  the  peripheral  filaments  of  the  facial 
nerve  have  resulted  in  facial  spasm.  Perhaps  this  condition 
is  most  frequently  met  with  as  an  evidence  of  some  reflex  act^ 
excited  through  some  other  cranial  nerves  ;  hence  we  find  it 
associated  with  such  causes  of  irritation  as  caries  of*  the  teeth, 
periostitis,  inflammatory  affections  of  the  eyeball,  lids,  or  con- 
junctiva. Remak  reports  a  case  where  a  diseased  condition 
of  the  brachial  plexus  caused  spasms  to  start  in  the  hand  and 
progress  along  the  side  of  the  neck  to  the  face,  again  illus- 
trating the  reflex  character  of  the  disease. 

It  is  such  cases  as  these  latter  that  often  test  the  ana- 
tomical knowledge  of  the  diagnostician,  since  a  command  of 
the  various  anastomoses  of  nerves  often  enables  the  skilled 
anatomist  to  detect  the  seat  of  irritation  far  from  the  apparent 
seat  of  disease,  and  thus  to  obviate  a  distressing  condition  by 
some  simple  medicinal  or  surgical  remedy. 

The  spasms  of  the  facial  muscles  may  assume  either  the 
tonic  or  clonic  character.  The  former  variety  is  observed  in 
such  conditions  as  tetanus,  the  late  rigidity  of  paralyzed  mus- 
cles, and  the  irritation  following  upon  severe  exposure  and 
too  intense  faradization  ;  while  the  latter  are  the  most  com- 
mon, and  result  in  those  convulsive  twitchings  of  the  forehead, 
eyes,  eyelids,  nose,  mouth,  cheeks,  and  tongue,  which  pro- 
duce the  most  extreme  and  often  ludicrous  distortion  of  the 
features.  I  have  known  such  clonic  spasms  of  the  face  to 
be  produced  by  the  irritation  of  worms  in  the  intestine  in 
children,  and,  in  one  case,  to  follow  uterine  disease  in  an 
adult.  A  peculiarity  of  these  spasms  is,  that  certain  muscles 
seem  to  contract  in  a  regular  sequence  or  rhythm,  and  that, 
although  the  contraction  may  be  prolonged  and  severe,  no 
fatigue  is  usually  complained  of  by  the  patient. 

PAEALYSIS   OF  THE   MUSCLES   OF   THE   FACE. 

The  general  appearance  of  a  sufferer  from  a  well-marked 
attack  of  '' Bell' s  paralysis  "  has  already  been  depicted  in  a 
cut,'  and  described  in  the  preceding  text,  under  the  effects 

^  See  page  42Y  of  this  volume. 


438  THE  CRANIAL  NERVES. 

of  section  of  the  facial  nerve ;  but  many  points  of  practical 
value  pertain  to  this  condition  which  have  not  as  yet  been 
mentioned,  and  which  help  greatly  in  making  a  diagnosis  as 
to  the  exciting  cause  and  the  seat  of  the  existing  lesion.  The 
symptoms  produced  by  any  impairment  to  the  free  action  of 
the  facial  nerve  vary  to  a  marked  extent  with  the  degree  of 
the  paralysis,  and  the  individual  branches  which  may  be  in- 
volved ;  and  distinctions  between  the  various  forms  of  facial 
paralysis,  met  with  in  a  large  clinical  field,  have  been  devel- 
oped, by  the  investigations  of  Romberg,  from  those  general 
propositions  first  advanced  by  Bell. 

In  studying  the  types  of  facial  paralysis,  we  may  start 
with  advantage  by  reviewing  the  different  groups  which  are 
clinically  recognized.  These  may  be  enumerated  as  the  intra- 
cranial ;  the  auditory  (where  the  existing  lesion  is  confined 
to  the  interior  parts  of  the  temporal  bone) ;  the  rheumatic ; 
the  traumatic ;  the  sypMUtic  /  and,  finally,  the  diphtheritic 
form.  We  may  also  have  the  paralysis  confined  to  one  side 
of  the  face,  the  unilateral,  or,  affecting  both  sides  of  the 
face,  the  bilateral,  or  facial  diplegia. 

In  the  intra-cranial  form  of  facial  paralysis,  the  lesion  of 
the  brain  is  usually  confined  either  to  the  base,  or  to  the  pons 
Varolii.  If  the  pons  Varolii  is  affected,  the  facial  nerve  will 
not  be  alone  involved,  as  a  rule,  but  a  partial  or  complete 
hemiplegia  will  usually  exist,  which  will  be  on  the  same  side 
of  the  body  as  the  facial  paralysis,  provided  the  upper  (an- 
terior) half  of  the  pons  is  the  seat  of  disease,  but  on  the  side 
opposite  to  the  facial  paralysis  (crossed  paralysis'),  if  the 
lower  (posterior)  part  of  the  pons  is  affected.  There  is,  per- 
haps, no  point  in  the  anatomy  of  the  encephalon  which  is  of 
more  certain  value  to  the  diagnostician  than  the  fact,  first 
pointed  out  by  Gubler,  that  a  line  drawn  transversely  across 
the  pons  Varolii  at  the  points  of  escape  of  the  trigemini 
marked  the  spot  of  probable  decussation  of  fibers  of  the  facial 
nerve ;  so  that,  if  a  lesion  be  anterior  to  this  line,  the  facial 

^  For  definition  of  this  term  and  the  various  types  met  with,  the  reader  is  referred  to 
the  previous  section. 


CAUSES  OF  BELVS  PARALYSIS.  439 

paralysis  will  correspond  to  the  hemiplegia,  but,  if  behind 
that  line,  the  condition  of  ''crossed  paralysis"  of  the  facial 
and  body  type  will  be  produced.  A  point  of  some  diagnostic 
value  in  the  detection  of  intra-cranial  lesions,  by  means  of 
the  facial  nerve,  is  afforded  by  the  degree  of  the  facial  paraly- 
sis, since  it  is  usually  complete  if  caused  by  lesions  of  the 
pons  Varolii  or  by  the  pressure  of  tumors  of  the  base  of  the 
cerebrum. 

The  second  form  of  facial  paralysis,  viz.,  that  dependent 
upon  some  abnormal  condition  within  the  temporal  hone, 
is  liable  to  follow  suppuration  or  haemorrhage  within  the 
aqueduct  of  Fallopius;  scrofulous  caries  of  the  temporal 
bone ;  local  degeneration  of  the  nerve  within  the  aqueduct 
of  Fallopius  ;  local  pressure  upon  the  nerve  from  tumors, 
etc. ;  and  traumatisms  of  all  kinds,  of  sufficient  intensity  to 
injure  the  deeper  parts  or  to  directly  involve  the  nerve 
itself. 

If  you  will  recall  the  anatomy  of  the  facial  nerve  within 
the  aqueduct  of  Fallopius,  and  the  branches  which  are  given 
off  in  that  canal,  you  will  be  better  able  to  appreciate  the 
points  afforded  by  this  anatomical  knowledge  in  the  diag- 
nosis of  the  seat  of  a  lesion  which  is  causing  facial  paraly- 
sis. We  have  already,  in  connection  with  the  effects  of 
section  of  the  facial  nerve,  mentioned  the  facial  deformity 
which  ensues ;  and  the  same  description  will  answer  for  the 
effects  of  disease  of  the  nerve,  or  pressure  upon  it,  after  it 
has  escaped  from  the  stylo-mastoid  foramen.  But  the  symp- 
toms to  which  I  now  propose  to  call  your  attention  are  not 
included  in  that  description,  since  they  are  due  to  branches 
which  are  given  off  by  the  facial  nerve  before  it  escapes  from 
the  temporal  bone ;  although  the  same  facial  deformity,  and 
all  the  evidences  of  impairment  of  the  nerve  on  the  distal 
side  of  the  stylo-mastoid  foramen,  will,  of  necessity,  be  also 
present. 

If  the  lesion  be  situated  above  the  point  of  origin  of  the 
chorda  tympani,  but  on  the  distal  side  of  the  petrosal  nerves, 
the  sense  of  taste  win  probably  be  affected  on  the  correspond- 


440  THE  CRANIAL  NERVES. 

ing  side  of  the  anterior  two  thirds  of  the  tongue ; '  but  the 
sense  of  taste  is  not,  as  a  rule,  abolished,  although  it  is 
greatly  diminished  in  acuteness.  How  this  nerve  affects  the 
sense  of  taste,  and  the  various  experiments  which  have  been 
recorded  concerning  it,  will  be  found  by  reference  to  preced- 
ing pages.' 

If  the  lesion  of  the  facial  nerve  be  situated  behind  the 
ganglionic  enlargement  from  which  the  three  petrosal  nerves 
arise,  the  patient  will  reveal  a  depression  of  the  arch  of  the 
palate  upon  the  affected  side ;  thus,  it  will  be  seen  to  hang 
lower  than  the  healthy  side,  and  to  approach  a  straight  line 
along  its  free  edge,  rather  than  that  of  a  marked  curve,  as  in 
health.  This  is  due  to  the  paralysis  of  the  levator  palati 
muscle,  which  is  supplied  with  motor  power  from  Meckel's 
ganglion,  through  the  large  petrosal  nerve.  In  addition  to 
this  deformity,  the  soft  palate  is  drawn  toward  the  unaffect- 
ed side  by  the  tensor  palati  muscle,  since  the  same  muscle 
of  the  paralyzed  side  is  no  longer  capable  of  acting,  as  it  is 
supplied  by  the  small  petrosal  nerve.  The  distribution  of  the 
small  petrosal  nerve  to  the  otic  ganglion  still  further  explains 
why,  in  this  type  of  cases,  the  secretion  of  the  parotid  gland 
of  the  affected  side  is  diminished ;  while  the  intimate  asso- 
ciation of  the  chorda  tympani  nerve  with  the  submaxillary 
gland  accounts  for  deficient  secretion  from  that  source. 

It  has  been  observed  that  the  sense  of  hearing  becomes  ex- 
cessively acute^  when  the  facial  nerve  is  affected  on  the  proxi- 
mal side  of  the  point  of  origin  of  the  petrosal  nerves.  This 
may  possibly  be  due  to  the  paralysis  of  the  tensor  tympani 
muscle,  as  suggested  by  Landouzy,  since  that  muscle  is  sup- 
plied with  motor  power  by  a  filament  derived  from  the  otic 
ganglion  ;  although  the  investigations  of  Brown- Sequard  seem 
to  point  to  a  vaso-motor  spasm  of  the  internal  ear,  resulting 
in  a  condition  of  hypersesthesia  of  the  acoustic  nerve. 

The  third  form  of  facial  paralysis  occurs  in  connection 

'  The  reader  is  referred  to  those  pages  in  which  the  gustatory  branch  of  the  fifth 
nerve  is  discussed,  since  authorities  differ  as  to  the  value  and  interpretation  of  this  symp- 
tom. 

'  See  page  406  of  this  volume. 


CAUSES   OF  BELL'S  PARALYSIS  441 

with  the  rJieumatic  diathesis.  It  is  well  known  that  the  in- 
fluence of  cold,  which  is  particularly  liable  to  favor  rheu- 
matic manifestations,  is  more  keenly  felt  in  the  region  of  the 
cheek  and  eyelids,  as  shown  by  Weber ;  and  the  experiments 
of  Wachsmuth,"  upon  the  effect  of  cold  upon  tHe  vaso-motor 
fibers  in  the  region  of  the  stylo-mastoid  foramen,  also  point 
to  the  retardation,  or,  possibly,  the  entire  suppression,  of  the 
blood  supply  to  the  facial  nerve,  as  the  explanation  of  this 
type  of  paralysis.  A  mild  form  of  periostitis  in  the  bony 
canals,  through  which  the  different  branches  of  the  facial 
nerve  pass,  may  also  occur  in  the  rheumatic  type  as  an  excit- 
ing cause. 

The  traumatic  types  of  facial  paralysis  may  involve  the 
entire  nerve  or  only  individual  branches.  Its  symptoms, 
therefore,  somewhat  depend  upon  the  situation  and  extent  of 
the  injury.  It  has  been  known  to  follow  severe  contusions  of 
the  face,  cheek,  or  neck,  incisions  made  by  the  surgeon,  saber 
cuts  and  gunshot  wounds,  the  compression  exerted  .by  the 
forceps  during  delivery,  the  pressure  of  growing  tumors,  sup- 
puration within  the  parotid  gland  or  lymphatics  of  that 
region,  and  the  pressure  caused  by  extensive  or  deep  cica- 
trices. This  type  of  paralysis  is  often  extremely  obstinate 
and  of  long  duration,  and  may  be  permanent ;  since  the  nerve 
may  have  undergone  changes  in  its  structure  or  the  muscles 
may  have  become  impaired. 

In  sypMlis^  facial  paralysis  is  sometimes  developed.  It 
may  thus  indicate  the  formation  of  intra-cranial  tumors  or 
meningeal  exudations,  which  either  press  upon  the  nerve 
trunk  or  interfere  with  its  fibers  of  origin.  It  may  also  be  an 
evidence  of  extra-cranial  lesions,  such  as  periostitis  of  the 
mastoid  region,  tumors  of  the  facial  or  cranial  bones,  or  sup- 
puration dependent  upon  caries  or  necrosis  of  the  temporal 
bone  (if  the  entire  nerve  be  affected),  or  of  some  of  the  facial 
bones,  if  individual  branches  only  show  evidences  of  pressure. 

Cases  are  on  record  where  the  symptoms  of  facial  paraly- 
sis have  followed  an  attack  of  dipJitJieria.     This  is  but  one  of 

^  As  quoted  by  Rosenthal. 


^2  THE  CRANIAL  NERVES. 

the  various  forms  of  paralysis  which  are  frequently  observed 
as  sequelse  of  this  peculiar  blood  poison. 

It  may  be  well  to  hastily  review  the  principal  complica- 
tions which  are  most  frequently  observed  in  connection  with 
facial  paralysis.  These  have  a  special  importance  to  the  sci- 
entific practitioner  in  enabling  him  to  diagnose,  not  only  the 
condition  of  the  patient,  but  also  the  seat  of  the  existing 
lesion. 

We  have  considered  the  effects  of  lesions  within  the  aque- 
duct of  Fallopius.  These  may  create  (in  addition  to  those  of 
the  facial  muscles)  symptoms  referable  to  the  impairment  of 
the  chorda  tympani  nerve  (see  page  439),  of  the  petrosal  ner\^es 
(see  page  440),  acoustic  manifestations,  or  an  effect  upon  the 
salivary  secretions. 

Intra-cranial  lesions  usually  cause  destruction  of  the  mo- 
tor power  of  the  entire  nerve,  and,  therefore,  of  all  of  its 
branches ;  hence,  we  are  liable  to  have  all  of  the  previous 
symptoms  present,  as  well  as  those  of  facial  deformity. 

Special  branches  of  the  nerve  may  be  individually  para- 
lyzed, and  thus  produce  symptoms  referable  only  to  those 
parts  in  which  the  motor  power  is  deficient.  The  anatomy  of 
the  separate  branches,  as  shown  in  the  cuts  on  previous 
pages,  will  help  you  to  understand  the  special  symptoms 
which  an  impairment  of  any  one  branch  would  produce. 

The  condition  of  bilateral  facial  paralysis^  or  '''facial 
diplegia.,''^  is  a  rare  form  of  disease.  It  implies  some  form  of 
pressure  or  degeneration,  which  shall  affect  the  nerve  of  each 
side  simultaneously  ;  hence  it  may  accompany  a  lesion  situ- 
ated in  the  anterior  half  of  the  pons,  which  crosses  the  median 
line  ;  an  exostosis  of  the  interior  surface  of  the  basilar  process 
of  the  occipital  bone ;  an  intra-cranial  aneurism  ;  and  the  pres- 
ence of  excessive  meningeal  exudation  at  the  base  of  the  brain. 
It  sometimes  accompanies  the  condition  of  labio-glosso-pha- 
ryngeal  paralysis  (Duchenne's  disease),  provided  the  lesion  ex- 
tends so  as  to  involve  the  nuclei  of  origin  of  the  facial  nerves  ; 
and  is  occasionally  met  with  in  the  course  of  certain  chronic 
cerebral  diseases.     Jaccoud  claims  that  the  spontaneous  atro- 


CAUSES   OF  FACIAL  DIPLEGIA.  443 

phy  of  both  facial  nerves  can  occur  without  an  exciting  cause 
of  a  local  character  being  detected  ;  and  the  same  opinion  is 
maintained  by  Pierreson/  who  found  a  hyperplasia  of  the 
connective  tissue  of  the  nerve  and  the  development  of  amy- 
loid corpuscles  to  constitute  the  pathological  changes. 

This  type  of  paralysis  may  be  due  to  peripheral  causes, 
such  as  exposure  to  intense  cold,  as  in  sleigh-riding,  rheu- 
matic inflammation  of  the  nerves,  and  diseases  of  the  petrous 
portion  of  the  temporal  bones  (necrosis,  caries,  syphilitic 
otitis,  suppurative  inflammation  of  the  middle  ear,  etc.). 

The  experiments  of  Schiif  upon  animals  in  whom  both 
facial  nerves  had  been  divided,  and  the  investigations  of  Trous- 
seau, Wachsmuth,'  and  Davaine,  have  helped  to  clear  up  the 
effects  of  this  double  lesion,  and  to  render  its  diagnosis  from 
Duchenne's  disease  more  positive  than  our  previous  knowl- 
edge would  permit.  In  the  human  race,  this  condition  is 
characterized  by  the  following  symptoms  :  a  fixed  and  im- 
movable countenance,  a  peculiar  drqoping  of  the  angles  of  the 
mouth,  a  collapsed  appearance  of  the  nostrils  during  inspira- 
tion, a  sinking  inward  of  the  cheeks  during  the  inspiratory 
effort,  and  a  protrusion  or  inflation  of  the  cheek  when  the  air 
is  expired.  The  tone  of  the  voice  becomes  of  the  most  dis- 
tinctly nasal  quality,  and  the  patient,  from  the  inability  to 
pronounce  the  labial  consonants,  is  almost  unable  to  make  the 
simplest  sentences  intelligible.  In  consequence  of  paralysis 
of  the  buccinator  muscles,  which  are  supplied  by  the  facial 
nerves,  the  act  of  mastication  becomes  embarrassed,  and  de- 
glutition is  greatly  interfered  with ;  hence  it  is  not  uncom- 
mon to  see  such  patients  use  the  finger  to  push  the  food  into 
the  grasp  of  the  isthmus  of  the  fauces,  so  as  to  swallow  the 
bolus.  When  the  head  is  inclined  forward,  the  saliva  runs 
from  the  mouth,  in  spite  of  all  efforts  to  prevent  it.  The  con- 
dition of  the  eyes,'  which  remain  wide  open  on  account  of  the 


'  As  quoted  by  Rosenthal. 
^  As  quoted  by  Hammond. 


3  In  both  the  unilateral  and  bilateral  forms  of  facial  paralysis,  the  patient  often  can 
avoid  the  irritation  of  dirt  and  the  intense  light  by  closing  the  eyelids  with  the  pressure 
of  the  finger,  or  by  a  strip  of  adhesive  plaster. 


444 


THE  CRANIAL  NERVES. 


paralysis  of  the  orbicularis  palpebrarum  muscles,  affords  a 
most  important  point  in  the  discrimination  between  this  dis- 
ease and  the  paralysis  of  Duchenne.  So  marked  is  this  de- 
formity that  the  patient  can  not  wink,  and  thus  the  tears  are 
not  distributed  over  the  globe  of  the  eye,  to  wash  off  any  dust 
which  may  enter ;  while,  on  account  of  the  paralysis  of  the 
tensor  tarsi  muscle,  the  tears  are  not  drawn  into  the  lachry- 
mal sac,  and  therefore  tend  to  flow  over  the  cheek  and  create 
scalding. 

THE  AUDITORY,  OR  EIGHTH  NERVE. 

This  nerve  is  strictly  one  of  special  sense,  namely,  that  of 
hearing.  It  arises  chiefly  from  a  gray  nucleus  in  the  floor 
of  the  fourth  ventricle  (where  its  fibers  form  the  so-called 


Fig.  1 1 5. — A  diagram  of  the  auditori/  nerve  and  its  branches. 

1,  auditory  nerve,  entering  the  meaius  audiiorins  intcrnus  ;  2,  communicating  filaments  to 
the  facial  nerve,  given  off  in  the  internal  auditory  canal ;  3,  filaments  given  off  to 
supply  the  cochlea;  4,  filaments  given  off  to  supply  the  posterior  semicircular  canal; 
6,  filaments  given  off  to  supply  the  saccule  ;  6,  filaments  given  off  to  supply  the  utri- 
cle ;  7,  filaments  given  off  to  supply  the  external  semicircular  canal;  8,  filaments 
given  off  to  supply  the  ampullce  of  the  superior  semicircular  caned. 

''linese  transversse"  which  decussate  in  the  median  line),  and 
also,  in  part,  from  three  other  nuclei  of  the  medulla  oblon- 
gata (page  267).  Some  of  its  fibers  may  be  also  traced  to  the 
flocculus  and  the  nucleus  fastigii  and  nucleus  dentatus  of 
the  cerebellum.  From  recent  statements  of  Lockhart  Clarke, 
additional  fibers  may  be  traced  from  the  auditory  nucleus, 
which  pass  directly  through  the  restif orm  body  of  the  medulla. 
The  course  of  the  nerve,  as  far  as  the  orifice  of  the  internal 


THE  AUDITORY,    OB  EIGHTH  NERVE.  445 

auditory  canal,  lies  parallel  with  that  of  the  facial  nerve,  since 
the  same  arachnoid  sheath  invests  them  both,  but,  before 
that  canal  is  reached,  a  filament  is  given  off  from  both 
these  nerves  to  form  an  intermediate  nerve,  called  the  ''pars 
intermedia,"  or  the  "nerve  of  Wrisberg."  This  intermediate 
portion  is  now  supposed  to  be  the  chief  source  of  origin  of  the 
chorda  tympani  nerve^  and  thus  to  be  connected  with  the 
special  sense  of  taste. 


FiQ.llQ.—BistHbution 0/ the cocldearnerve  in  the  spiral  lamina  of  the  cochlea  {the  cochlea 
is  from  the  right  side  and  is  seen  from  its  antero-inferior  part).     (Sappey.) 

1,  trunk  of  the  cochlear  nerve ;  2,  2,  2,  membranous  zone  of  the  spiral  latnina ;  3,  3,  3, 
terminal  expansion  of  the  cochlear  nerve,  exposed  in  its  whole  extent  by  the  removal 
of  the  superior  plate  of  the  lamina  spiralis ;  4,  orifice  of  communication  of  the  scala 
tympani  with  the  scala  vestibuli. 

The  color  of  the  auditory  nerve  filaments  is  grayish.  The 
filaments  differ  from  those  of  the  other  cerebro-spinal  nerves 
(excepting  those  of  special  sense)  in  having  a  softer  consist- 
ence. Some  of  the  later  researches  seem  to  show  that  the 
filaments  of  this  nerve  are  destitute  of  the  ' '  white  substance 
of  Schwann,"  and  thus  resemble  those  of  the  olfactory  nerve, 
while  the  axis  cylinders  are  of  very  large  size  as  compared 
with  those  of  other  nerves.  It  is  also  claimed  that  small,  nu- 
cleated, ganglionic  enlargements  can  be  demonstrated  along 
the  course  of  these  fibers  of  the  trunk  of  the  nerve,  but  the 
minute  anatomy  of  the  auditory  nerve  is  yet  a  subject  for 
further  investigation. 

Within   the  internal    auditory  canal,   the    eighth    nerve 
81 


446 


THE  CRANIAL  NERVES. 


divides  into  two  branclies,  tlie  anterior  of  which  supplies  the 
cochlea,  while  the  posterior  branch  is  distributed  to  the  semi- 
circular canals  and  to  the  saccule  and  vestibule.  These  two 
main  branches  are  given  off  close  to  the  meatus  auditorius 
internus. 

At  the  bottom  of  the  internal  auditory  canal,  the  three 
subdivisions  of  the  vestibular  nerve  pass  through  srriall  open- 


mmmuk^ 


Fig.  IIY. — General  view  of  the  organ  of  hearing.    (Sappey.) 

1,  pinna ;  2,  cavity  of  the  ctincha,  on  the  walls  of  which  are  seen  the  orifices  of  a 
great  number  of  sebaceous  p^lands ;  5,  external  auditory  meatus;  4,  angular  pro- 
jection formed  by  the  union  of  the  anterior  portion  of  the  concha  with  the  posterior 
wall  of  the  auditory  canal ;  5,  openings  of  the  cerumlnous  glands,  the  most  internal 
of  which  form  a  curved  line,  which  corresponds  with  the  beginning  of  the  osseous 
portion  of  the  external  meatus  ;  6,  membrana  tympani  and  the  elastic  fibrous  mem- 
brane which  forms  its  border ;  7,  anterior  portion  of  the  incus ;  8,  malleus  ;  9,  han- 
dle of  the  malleus  applied  to  the  internal  surface  of  the  membrana  tympani,  which  it 
draws  inward  toward  the  projection  of  the  promontory  ;  10,  tensor  tympani  muscle, 
the  tendon  of  which  is  reflected  at  a  right  angle  to  become  attached  to  the  superior 
portion  of  the  handle  of  the  malleus;  11,  tympanic  cavity  ;  12,  Eustachian  tube,  the 
internal  or  pharyngeal  extremity  of  which  has  been  removed  by  a  section  perpen- 
dicular to  its  curve;  13,  superior  semicircular  canal ;  14,  posterior  semicircular  ca- 
nal; 15,  external  semicircular  canal ;  16,  cochlea  ;  17,  internal  auditory  canal ;  18, 
facial  nerve  ;  19,  large  petrosal  branch,  given  off  from  the  ganglioform  enlargenjcnt 
of  the  facial  and  passing  below  the  cochlea  to  go  to  its  distribution  ;  20,  vestibular 
branch  of  the  auditory  nerve  ;  21,  cochlear  branch  of  the  auditory  nerve. 

ings  in  a  cul-de-sac  situated  at  that  point,  and  are  distributed 
to  the  utricle,  the  saccule,  and  the  three  ampullje. 

The  cochlear  nerve,  which  is  the  other  main  branch  of  the 
auditory,  enters  the  base  of  the  modiolus,  and  its  filaments 


DISTRIBUTION  OF  AUDITORY  NERVE.  447 

subsequently  escape  from  the  central  canal  of  the  modiolus 
through  minute  canals,  which  enable  them  to  reach  their 
point  of  distribution  in  the  internal  portion  of  the  cochlea. 
The  terminal  filaments  of  this  nerve  are  now  believed  to  be 
connected  with  the  spindle-shaped  cells  of  the  orga-n  of  Corti. 

It  is  impossible,  within  the  compass  of  this  lecture,  to  en- 
ter into  the  minute  anatomy  of  the  ear  with  sufficient  detail 
to  enable  you  to  properly  appreciate  the  mechanism  by  which 
the  waves  of  sounds,  produced  from  without,  are  transmitted 
to  the  membrana  tympani,  and  subsequently  to  the  cochlea, 
where  they  are  perceived  by  the  auditory  nerve  filaments.  To 
properly  appreciate  the  difficulties  which  arise  in  determining 
the  exact  method  by  which  the  human  ear  is  enabled  to  de- 
termine not  only  the  intensity  of  the  sound  perceived,  but 
also  its  pitch,  quality,  and  musical  properties,  not  only 
would  the  anatomy  have  to  be  given  in  detail,  but  many  of 
the  laws  of  physics  discussed.  The  following  general  state- 
ments, however,  may  assist  you  in  studying  this  complicated 
subject,  and  afford  an  explanation  of  some  of  those  symp- 
toms of  disease  which  are  referred  to  the  ear. 

The  diagram  shown  you  on  the  blackboard '  is  designed  to 
assist  you  to  grasp  some  of  the  principal  points  in  the  ana- 
tomical construction  of  the  ear,  which  are  necessary  for  the 
clear  comi3rehension  of  the  physiology  of  audition.  It  can  be 
perceived  that  the  external  auditory  canal  and  its  accessory 
portion  which  we  call  the  ear  or  auricle  (which  is  placed 
on  the  exterior  of  the  skull  for  the  purpose  of  deflecting  the 
waves  of  sound  into  that  canal)  lie  external  to  the  membrana 
tympani  ;  and,  for  that  reason,  all  of  these  parts,  viz.,  the 
cartilages  of  the  pinna,  its  ligaments,  the  bony  canal  leading 
to  the  membrana  tympani,  and  its  cutaneous  lining,  are  in- 
cluded under  the  general  term  ''the  external  ear,'"  in  contrast 
to  the  chambers  which  lie  deeply  within  the  temporal  bone, 
called  the  middle  ear,  or  "  the  cainty  of  the  tympanum,''  and 
the  internal  ear,  or  the  '-^  labyrinth y 

The  middle  ear,  or  "  tympanum,''  lies  between  the  mem- 

^  See  diagram  further  on  in  the  chapter. 


448  THE  CRANIAL  NERVES. 

brana  tympani  and  the  internal  ear,  or  "  labyrintli,"  and  is 
contained  within  the  petrous  portion  of  the  temporal  bone. 
It  communicates  with  the  pharynx,  by  means  of  the  Eusta- 


Fio.  118. — A  diagram  to  illustrate  the  mechanism  of  the  act  of  hearing.  j 

A,  the  auditory  canal  (the  arrow  showing  the  waves  of  sound  entering) ;  B,  the  cavity  of  i 
the  middle  ea)\  or  "  tympanum  ") ;  C,  the  utricle,  communicating  with  the  semicircu- 1 
tar  canals ;  D,  the  saccule,  communicating  with  the  scala  vestihuH  of  the  cavity  of  the  : 
cochlea ;  E,  the  Eustachian  tube,  allowing  of  the  entrance  of  air  into  the  middle  ear  ^ 
from  the  pharynx;  1,  the  membrana  tympani,  which  first  receives  the  vibrations  of  | 
the  waves  of  sound  ;  2,  the  chain  of  bones,  which  transmit  these  vibrations  to  the  mem-  i 
brane  covering  the  fenestra  ovalis  (annular  ligament  of  the  stapes) ;  3,  the  membrane, '. 
covering  the  fenestra  ovalis  (annular  ligament  of  the  stapes) ;  4,  the  foramen  rotun-  \ 
dam,  where  the  waves  of  sound  return  to  the  cavity  of  the  middle  ear  and  are  lost  I 
(membrana  tympani  secundaria) ;  6,  the  ampullte  of  the  semicircular  canals  ;  6,  the  i 
semicircular  canals  ;  7,  the  "  scala  vestibuli  "  of  the  cochlea ;  8,  the  cupola,  at  the  apex  : 
of  the  cochlea,  where  the  scala  vestibuli  and  the  scala  tympani  of  the  cochlea  join  j 
each  other;  9,  the  "  scala  tympani,^'*  leading  downward  from  the  cupola  of  the  cochlea ; 
to  the  foramen  rotundum ;  10,  internal  auditory  canal,  where  the  auditory  nerve  ] 
enters.  ' 

chian  tube,  and  is  thus  enabled  to  afford  free  access  to  the! 
air  of  the  external  world,  and  insure  the  same  density  of  at-j 
mosphere  on  both  sides  of  the  membrana  tympani.  It  isi 
this  anatomical  arrangement  that  causes  gunners  to  hold  thei 
mouth  wide  open  when  exploding  large  pieces  of  ordnance,  to| 
avoid  a  rupture  of  the  membrana  tympani,  since  the  waves  of ! 
sound  can  thus  enter  the  Eustachian  tube  at  the  same  time; 
that  they  pass  down  the  external  auditory  canal,  and  the; 
membrana  tympani  should,  theoretically,  be  made  to  stand; 


TEE  MIDDLE  EAR. 


449 


motionless,  if  the  Eustachian  tube  were  wide  open,  since  the 
waves  of  sound  upon  each  side  of  the  membrane  would  neu- 
tralize each  other/  In  the  cavity  of  the  middle  ear,  a  chain 
of  small  bones  is  so  arranged  as  to  afford  a  source  of  trans- 
mission of  the  impulses  of  sound  from  the  membrana  tym- 
pani  to  the  fenestra  ovalis,'  which  is  closed  by  the  stapes' 


Fig.  119. —  Ossicles  of  (he  tympanum  of  the  right  side,  magnified  4  diameters.  (Arnold.) 
A,  malleus ;  1,  its  head  ;  2,  the  handle  ;  3,  lonjr,  or  slender  process  ;  4,  short  process  ;  B, 
incus  ;  1,  its  body;  2,  the  long  process  with  the  orbicular  process  ;  3,  short,  or  pos- 
terior  process  ;  4,  articular  surface  receiving  the  head  of  the  malleus  ;  C,  stapes  ;  1, 
head  ;  2,  posterior  crus  ;  3,  anterior  crus ;  4,  base  ;  C*  base  of  the  stapes  ;  D,  the 
three  bones  in  their  natural  connection  as  seen  from  the  outside ;  a,  malleus ;  6, 
incus ;  c,  stapes. 

and  its  annular  ligament.  Thi^  chain  of  bones  is  suspend- 
ed by  a  ligament  attached  to  the  roof  of  the  middle  ear,  and 
the  separate  bones  are  connected  together  by  joints*  lined 
with  synovial  membranes,  so  that  the  slightest  movement  is 
readily  carried  from  one  to  the  other.  Muscles  are  also  at- 
tached to  these  bones,  for  the  object  of  bringing  the  mem- 

'  Valsalva's  method,  "  which  consists  of  making  a  powerful  expiration,  with  the  mouth 
and  nostrils  closed,"  is  also  used  if  the  ear  be  stopped  with  cotton  at  the  same  time. 

*  A  doctrine  first  suggested  in  1851  by  Edward  Weber,  and  subsequently  verified  by 
experiments  in  1868  by  Politzer. 

^  One  of  the  small  bones  of  the  middle  ear. 

*  Helmholtz  first  described  the  exact  nature  of  the  joint  between  the  malleus  and  the 
incus.  He  compared  it  to  "  a  joint  used  in  certain  watch-keys,  where  the  handle  can  not 
be  turned  in  one  direction  without  carrying  the  steel  shell  with  it,  while  in  the  other  direc- 
tion it  meets  with  only  a  slight  resistance."  This  device  assists  to  convert  the  bones  into 
a  state  of  resistance,  resembling  that  of  a  solid  piece  of  bone,  when  muscular  action  locks 
this  joint  firmly. 


450  THE  CRANIAL  NERVES. 

brana  tympani  and  the  bones  themselves  into  the  best  possi- 
ble condition  for  the  accurate  appreciation  of  sound  im- 
pulses.' The  cavity  of  the  middle  ear  is  in  communication 
with  the  cells  in  the  mastoid  portion  of  the  temporal  bone, 
and  some  additional  effect  may  be  thus  produced  upon  the 
vibrations  of  the  air  within  the  middle  ear.' 


Fio.  120. — The  left  bony  lahyrinthof  a  vcic-born  chihl,  f^rvard  cmd  outward  view, 
fed  from  a  photograph.     (Riidinger.) 

1,  the  wide  canal,  the  bcjrinning  of  the  spiral  canal  of  the  cochlea ;  2,  the  fenestra  ro- 
tunda; 3,  the  second  turn  of  the  cochlea;  4,  the  final  half  turn  of  the  cochlea; 
5,  the  border  of  the  bony  wall  of  the  vestibule,  situated  between  the  cochlea  and 
the  semicircular  canal:* ;  6,  the  superior,  or  sagittal  semicircular  canal ;  7,  the  portion 
of  the  superior  semicircular  canal  bent  outward ;  8,  the  posterior,  or  transverse 
semicircular  canal ;  9,  the  portion  of  the  posterior  connected  with  the  superior  semi- 
circular canal ;  10,  point  of  junction  of  the  superior  and  the  posterior  semicircular 
canal;  11,  the  ampulla  ossea  externa;  12,  the  horizontal,  or  external  semicircular 
canal. 

The  internal  ear,  or  ^^  labyrinth,''^  lies  within  the  petrous 
portion  of  the  temporal  bone,  and  internal  to  the  tympanum. 
It  consists  of  a  series  of  chambers,  hollowed  out  within  the 
bone,  called  the  vestibule,  the  cochlea,  and  the  semicircular 

'  The  ioisor  tympani  muscle,  on  account  of  a  peculiar  arrangement  of  the  joint  be- 
tween the  malleus  and  the  incus,  renders  all  the  articulations  firm,  tightens  the  little  liga- 
tures, and  presses  the  stapes  ac^ainst  the  fenestra  ovalis,  thus  bringing  it  in  contact  with 
the  fluids  of  the  vestibule.     See  foot-note  on  page  449. 

*  For  the  surcrical  application  of  this  arrangement,  see  article  on  the  bones  of  the 
head,  by  the  author,  "  New  York  ^ledical  Ilecord,"  October  16,  18S0. 


THE  INTERNAL  EAR. 


451 


canals.,  within  each  of  which  a  membranous  tube  is  sus- 
pended between  two  liquids,  one  within  the  tube,  the  '^en- 
dolymph,"  and  one  between  the  tube  and  the  bony  walls,  the 
* '  perilymph. "     This  membranous  portion  is  called  the  ' '  mem- 


Fig.  121. — Diagram  of  the  labyrinth,  vestibiikj  and  semicircular  canals.     From  a  photo- 
graph,  and  somewhat  reduced.     (Uudingcr.) 

Upper  figure:  1,  utricle;  2,  saccule;  3,  5,  membranous  cochlea;  4,  canalis  reuniens;  '6, 
semicircular  canals. 

Lower  figure:  1,  utricle;  2,  saccule;  3,  4,  6,  ampullae;  5,  V,  8,  9,  semicircular  canals; 
10,  auditory  nerve  (partly  diagrammatic);  11,  12,  13,  14,  15,  distribution  of  the 
branches  of  the  nerve  to  the  vestibule  and  the  semicircular  canals ;  16,  ganglioform 
enlargement. 


hranous  lahyrinth^^^  and  is  an  exact  reproduction  of  the 
bony  labyrinth,  except  that  it  is  smaller  in  point  of  size,  so  as 
to  admit  the  presence  of  fluid  between  it  and  the  bone.  It 
serves  as  a  support  for  the  terminal  filaments  of  the  auditory 
nerce,  which,  by  being  suspended  between  two  fluids,  are  en- 


452  TEE  CRANIAL  NERVES.  \ 

abled  not  only  to  perceive  the  slightest  vibrations  of  the  i 
fluids/  but  are  also  thus  protected  from  the  possibility  of  in-  | 
jury,  which  would  be  great  were  they  placed  in  contact  with 
the  bone.  The  membranous  labyrinth  which  fills  the  cavity  i 
of  the  vestibule  is  divided  into  two  portions,  called  the  saccule  \ 
and  the  utricle;  the  former  of  which  communicates  directly  j 
with  the  cochlea,  while  the  latter  communicates  with  the  - 
semicircular  canals,  as  can  be  seen  in  the  diagram.  1 

The  cochlea  is  essentially  that  part  of  the  internal  ear  J 
which  is  enabled  to  appreciate  most  of  the  important  elements  \ 
of  sound,  viz.,  its  note  and  quality.''    It  consists  of  an  exca-  • 


Fig.  122. — A  transverse  section  of  the  spiral  canal  of  the  cochlea  {diagrammatic).^  \ 

S.  v.,  the  scala  vestibuli  ;  S,  M.,  the  scala  media  ;  S.  T.,  the  scala  tympani ;  1,  mem-  \ 
brane  of  Rcissner ;  2,  "  organ  of  Corti^''  covered  by  the  *'  mcmbrana  iectoria,''^  or  : 
"  membrane  of  Corti  "  ;  3,  mcmbrana  basilaris  ;  4,  ligamentum  spiralis,  extending 
the  whole  length  of  the  spiral  canal  of  the  cochlea ;  6,  upper  layer  of  the  lamina  : 
spiralis  ossea  ;  6,  lower  layer  of  the  lamina  spiralis  ossea ;  7,  a  nerve  filament  es-  i 
caping  from  the  central  canal  of  the  modiolus,  and  going  to  the  organ  of  Corti  ;  8,  a  1 
ganglion  attached  to  the  nerve  filament,  called  the  "  ganglion  spirale."  ! 

vation  in  the  temporal  bone  which  resembles,  in  its  construe-  | 
tion,  the  shell  of  a  snail,  having  a  central  pillar,  the  modio-  j 
lus,  which  runs  from  its  base  to  its  apex,  and  a  spiral  canal,  > 

'  It  is  a  well-recognized  law  of  physics  that  the  fluids  transmit  vibrations  in  every  | 
direction  with  equal  force,  and,  therefore,  no  better  medium  could  possibly  be  had  for 
the  auditory  nerve  filaments  to  be  in  contact  with. 

*  Complete  destruction  of  the  cochlea  probably  causes  total  deafness,  while  destruction  \ 
of  the  semicircular  canals  does  not  seem  to  have  any  marked  effect  upon  the  ability  to  i 
appreciate  sound.        ^  I 

^  l-'rom  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney),  New  York,  1880. 


CONSTRUCTION  OF  THE  COCHLEA. 


453 


running  around  this  central  portion  for  two  and  a  half  com- 
plete turns.  The  spiral  canal  of  the  cochlea  is  divided  into 
three  portions  called  the  scala  vestihuli^  scala  tympani,  and 
the  scala  media.'^    The  first  communicates,  at  its  lower  part, 


Fig 


a-b, 


123. — Vertical  section  of  the  organ  of  Corii  of  the  doff,  magnified  800  diameters. 

(Waldeyer.) 
homogeneous  layer  of  the  basilar  membi'ane  ;  v,  tympanic  layer,  with  nuclei,  granu- 
lar cell  protoplasm,  and  connective  tissue  ;  «],  tympanic  lip  of  the  crista  spiralis  ;  c, 
thickened  portion  of  the  basilar  membrane ;  d,  spiral  vessel ;  e,  blood-vessel ;  /,  /«, 
bundle  of  nerves  ;  g^  epithelium  ;  z,  inner  hair  cell,  with  its  basilar  process,  k  ;  I, 
head-plate  of  the  inner  pillar ;  w?,  union  of  the  two  pillars ;  ?^,  base  of  the  inner 
pillar ;  o,  base  of  the  outer  pillar  ;  />,  q,  r,  outer  hair  cells,  with  traces  of  the  cilia ; 
^,  bases  of  two  other  hair  cells  ;  «,  Hensen's  prop  cell ;  /-/i,  lamina  reticularis  ;  lo^ 
nerve  fiber  passing  to  the  first  hair  cell,  p. 


with  the  vestibule  ;  hence  its  name  ;  the  second  terminates  in 
the  middle  ear,  and  hence  its  name ;  while  the  third  is,  in 

^  The  experiments  of  Laborde  (Dcs  fonctions  du  lima9on,  "  Trib.  M4d.,"  Septembre 
12,  1880)  to  determine  the  function  of  the  cochlea  were  made  upon  the  Guinea-pig,  an 
animal  in  whom  the  organ  is  particularly  accessible.  The  following  facts  were  considered 
by  him  as  fully  proven  :  1,  Destruction  of  the  cochlea  had  no  effect  in  the  production  of 
vertigo  or  disturbances  of  coordination ;  2,  destruction  of  the  cochlea  produced  complete 
deafness,  which,  however,  did  not  appear  until  several  days  after  the  operation. 

He  concludes,  from  these  facts :  1,  That  the  auditory  nerve  contains  both  motor  and 
se7i8ory  fibers,  the  former  being  distributed  to  the  semicircular  canals,  the  latter  to  the 
saccule,  utricle,  and  cochlea  ;  2,  that  the  cochlea  is  not  the  only  organ  for  the  appreciation 
of  sound,  since  the  utricle  and  saccule  participate,  to  some  unknown  extent,  in  that  func- 
tion ;  3,  that  the  deafness  which  occurs  after  excision  of  the  cochlea  alone  is  probably 
due  to  an  extension  of  inflammation  to  the  utricle  and  saccule,  or  to  the  formation  of  a 
rigid  cicatrix,  which  prevents  the  transmission  of  an  auditory  impulse  to  those  parts. 
While  these  facts  need  subsequent  confirmation  (since  the  experiments  are  by  no  means 
conclusive),  they  are  worthy  of  due  consideration  in  the  discussion  of  this  complicated 
and  imperfectly  understood  organ. 


454 


THE  CRANIAL  NERVES. 


reality,  but  a  space  partitioned  off  from  the  scala  vestibuli 
for  the  protection  of  the  true  organ  of  hearing,  ''the  organ 
of  Corti/'  The  preceding  diagram  (Fig.  122)  will  help  to  make 
this  plain  to  you. 

This  figure  represents,  in  a  diagrammatic  way,  the  appear- 
ance of  a  longitudinal  section  of  the  spiral  cord  in  the  cochlea, 
in  any  portion  of  its  two  and  a  half  turns  around  the  modio- 
lus. It  will  be  perceived  at  a  glance  that  the  canal  is  divided 
into  an  upper  {s.  v.)  and  a  lower  {s.  t.)  portion,  partly  by  bone 
(5  and  6)  and  partly  by  membrane  (3).  It  will  also  be  readily 
seen  that  a  portion  of  the  scala  vestibuli  is  divided  off  by  the 
membrane  of  Reissner^  and  that  thus  a  separate  cavity  is 
formed  throughout  the  whole  length  of  the  spiral  canal,  called 
the  "scala  media."  Within  this  last-named  cavity  will  be 
noticed  a  body  covered  with  hair-like  processes,  "the  organ 
of  Corti,^''  which  rests  ,upon  the  membrane  forming  the  floor 
of  the  scala  media,  and  called  for  that  reason  the  ''basilar 


Fig.  121. — The  two  pillars  of  the  organ  of  Corti.     (Sappey.) 

A,  external  pillar  of  the  organ  of  Corti :  1,  body,  or  middle  portion  ;  2,  posterior  extrem- 

ity^ or  base  ;  3,  cell  on  its  internal  side  ;  4,  anterior  extremity ;  5,  convex  surface  by 
which  it  is  joined  to  the  internal  pillar ;  6,  prolongation  of  this  extremity. 

B,  internal  pillar  of  the  organ  of  Corti  :   1,  body,  or  middle  portion ;  2,  posterior  extrem- 

ity ;  3,  cell  on  its  external  side  ;  4,  anterior  extremity  ;  5,  concave  surface  by  which 
it  is  joined  to  the  external  pillar ;  6,  prolongation,  lying  above  the  corresponding 
prolongation  of  the  external  pillar. 

C,  the  two  pillars  of  the  organ  of  Corti,  united  by  their  anterior  extremity,  and  forming 

an  arcade,  the  concavity  of  which  looks  outward :  1,  1,  body,  or  middle  portion  of 
the  pillars  ;  2,  2,  posterior  extremities  ;  8,  3,  cells  attached  to  the  posterior  extrem- 
itics ;  4,  4,  anterior  extremities  joined  together ;  5,  terminal  prolongation  of  this 
extremity. 


membrane^  There  is,  furthermore,  shown  in  this  figure  the 
means  by  which  the  terminal  filaments  of  the  cochlear  nerve 
(one  of  the  branches  of  the  auditory  nerve)  escape  from  the 
central  canal  of  the  modiolus  and  reach  the.  scala  media. 


THE  ORGAN  OF  CORTL  455 

Such  a  figure  will  greatly  assist  you  to  properly  appreciate 
the  discussion  of  the  function  of  each  of  these  various  parts, 
and  also  enable  you  to  grasp  the  principal  points  in  the 
physiology  of  the  act  of  hearing,  which  are  to  be  con- 
sidered. 

The  organ  of  Corti  may  be  compared  to  a  harp,  since  its 
rods  are  of  different  lengths.  It  is  a  continuous  structure  for 
the  entire  course  of  the  spiral  canal  of  the  cochlea.  Helm- 
holtz  has  advanced  the  theory'  that  the  several  thousand 
strings  of  this  organ  admit  of  the  appreciation  of  all  varieties 
of  musical  tone,  since  each  note  or  chord  creates  a  vibration 


Fig.  125. — Distribution  0/  the  cochlear  nerve  in  the  spiral  lamina  of  the  cochlea  {the  cochlea 
is  from  the  right  side  and  is  seen  from  its  anteroinferior  part).     (Sappey.) 

1,  trunk  of  the  cochlear  nerve;  2,  2,  2,  membranous  zone  of  the  spiral  lamina;  3,  3,  3, 
terminal  expansion  of  the  cochlear  nerve,  exposed  in  its  whole  extent  by  the  removal 
of  the  superior  plate  of  the  lamina  spiralis ;  4,  orifice  of  communication  of  the  scala 
tympani  with  the  scala  vestibuli. 

in  those  strings  only  which  are  necessary  to  reproduce  it,  in 
the  same  way  as  a  piano,  when  a  note  is  sounded,  will  create 
a  vibration  in  the  same  string  of  an  adjoining  instrument. 
Hensen,  however,  claims  that  the  basilar  membrane  is  com- 
posed of  elastic  fibers  of  varying  lengths,''  and  that  these 
separate  fibers  are  thrown  into  vibration  by  sounds  carried  to 
the  cochlea,  which,  in  turn,  transmit  their  vibration  to  the 

'  This  theory  is  opposed  by  the  facts  that  the  rods  of  Corti  are  not  elastic,  and  they 
are  absent  irt  birds,  who  can  unquestionably  perceive  sound. 
-  By  some  authors  this  theory  is  attributed  to  Helmholtz. 


456  THE  CRANIAL  NERVES. 

organ  of  Corti  lying  upon  them,  and  thus  inform  the  auditory- 
nerve  filaments  of  the  effect  of  each  individual  sound.' 

In  the  act  of  hearing,  the  vibrations  produced  within  the 
memhrana  tympani  by  the  waves  of  sound  are  transmitted 
across  the  cavity  of  the  middle  ear,  to  a  membrane  covering 
an  opening  nearly  opposite  the  external  drum,  called  the 
fenestra  ovalis,  by  means  of  a  chain  of  small  bones  within 
the  cavity  of  the  middle  ear,  and,  by  means  of  secondary 
vibrations  thus  produced  within  this  latter  membrane,  the 
impulse  is  transmitted  to  the  fluids  of  the  vestibule.  The 
vibrations  now  travel  along  the  fluids  of  the  scala  vestibuli  of 
the  cochlea  and  of  the  semicircular  canals,  thus  passing  in 
two  different  directions.  In  the  semicircular  canals,  accord- 
ing to  some  observers,  the  direction  from  which  the  sound 
springs  is  perceived,"  while  the  vibrations  carried  along 
the  scala  media '  in  the  cochlea  are  transmitted  to  the  fila- 
ments of  the  auditory  nerve  in  the  "organ  of  Corti,"  proba- 
bly by  means  of  vibrations  of  the  membrana  hasllaris^  thus 
affording  the  appreciation  of  the  note  and  the  quality  of 
the  sound  perceived.  After  reaching  the  apex  of  the  coch- 
lea, the  vibrations  are  transmitted  from  the  scala  vestibuli 
downward  along  the  course  of  the  scala  tympani  till  they 
reach  the  "membrana  tympani  secundaria,"  which  covers 
iki!^  fenestra  rotunda^^  ^\L'dii^  they  are  lost,'  being  no  longer 

'  The  memhrana  teetoria,  or  "  membrane  of  Corti,^^  probably  acts  as  a  damper,  to 
arrest  the  vibrations  excited  within  the  scala  media,  as  its  situation  suggests  no  other  pos- 
sible function. 

'  The  function  of  the  semicircular  canals  is  yet  a  matter  of  doubt,  and  is  now  receiv- 
ing the  attention  of  experimental  physiologists.  They  are  supposed  by  some  authors  to 
relieve  excessive  pressure  within  the  labyrinth  when  the  stapes  is  driven  too  forcibly  in- 
ward ;  and,  by  others,  to  secrete  thcjluid  of  the  labyrinth  ;  while  by  some  they  are  consid- 
ered to  be  the  external  organs  of  coordination  of  muscular  movement. 

'  The  saccule  communicates  with  the  scala  media  by  means  of  a  small  canal  (shown 
in  Fig.  121),  called  the  "canalis  reuniens." 

*  An  opening  in  the  inner  wall  of  the  cavity  of  the  middle  ear. 

*  According  to  some  authorities,  the  vibrations  in  the  membrana  tympani  secundaria 
are  created,  simultaneously  with  those  at  the  fenestra  ovalis,  by  the  vibrations  of  the 
air  in  the  middle  car  created  by  the  movements  of  the  external  drum  membrane,  and 
an  impulse  thus  travels  simultaneously  along  the  scala  tympani  and  the  scala  vestibuli, 
both  going  in  the  same  direction^  to  meet  each  other  at  the  aipola.  They  consider  the  second 
drum,  at  the  foramen  rotundum,  as  a  proof  of  this  function,  but  it  must  be  apparent  to  any 
one  that  all  the  openings  of  the  labyrinth  into  the  middle  ear  must  be  closed  in  some  way 


PHYSIOL 00 Y  OF  A UDITION.  457 

transmitted,  on  account  of  the  absence  of  any  conducting 
medium. 

The  free  entrance  of  air  to  the  cavity  of  the  tympanum, 
or  the  middle  ear,  affords  an  equal  density  of  air  upon  either 
side  of  the  memhrana  tympanic  and  thus  insures  a  vibration 
of  that  membrane  in  absolute  unison  with  the  vibrations  of 
the  sound  which  it  is  called  upon  to  record,  as  the  waves  pass 
down  the  external  auditory  canal. 

The  function  of  the  organ  of  Corti^  of  the  memhrana  basi- 
laris,  or  of  the  otoliths,  can  not  be  stated  with  any  degree  of 
certainty,  since  new  discoveries  are  constantly  being  made, 
although  some  theories  of  their  functions  have  been  already 
given. 

The  minute  construction  of  the  scala  media  and  its  con- 
tained organs  can  be  found  by  reference  to  more  extensive 
treatises. 

CLINICAL    POIi^rTS    OF    Il^^TEREST    DEPEN^DEi^^T    UPOIf    THE    AUDITORY 

NERVE. 

In  attacks  of  auditory  vertigo,  or  Meniere's  disease,  there 
is  much  more  than  ordinary  giddiness.    The  patient  will  often 

to  prevent  the  escape  of  the  perilymph.  While  it  is  difficult  to  positively  decide  this  point, 
I  am  personally  inclined  to  regard  the  foramen  rotundmn  as  the  seat  of  termination  of 
wave  sounds,  rather  than  a  means  of  transrnimon  of  impulses  to  the  fluids  of  the  cochlea. 
Dr.  A.  H.  Buck,  in  a  late  tieatise  on  the  "  Diagnosis  and  Treatment  of  Ear  Diseases," 
again  advocates  theories  long  maintained  by  him  as  to  the  physiology  of  audition,  which 
may  be  thus  given  :  The  impulse  of  the  stapes,  at  the  fenestra  ovalis,  is  carried  by  means 
of  the  perilymph  directly  into  the  scala  vestibuli.  This  causes  compression  of  the  fluid  in 
the  scala  media,  which,  in  turn,  causes  pressure  upon  and  movement  of  the  elastic  "  mem- 
brana  basilaris."  The  pressure  is  thus  transmitted,  for  a  second  time,  to  the  fluid  in  the 
scala  tympani,  and,  as  fluids  are  incompressible,  the  membrana  tympani  secundaria,  which 
closes  the  foramen  rotundum,  is  forced  info  the  cavity  of  the  middle  ear  until  the  force 
is  expended,  when  it  returns  to  its  normal  condition.  It  will  be  thus  perceived  that  he 
discards  the  saccule  and  the  cana'is  rcunicns  as  a  channel  for  the  passage  of  the  acoustic 
wave.  He  also  questions  the  existence  of  any  communication,  at  the  cupola,  between  the 
scala  vestibuli  and  the  scala  tympani.  While  his  theory  seems  ingenious,  and  perhaps 
more  in  accordance  with  fact  than  the  older  views,  and  is  well  illustrated  by  diagrams 
and  supported  by  some  carefully  conducted  experiments,  still  it  can  not,  as  yet,  be  said 
to  be  positively  confirmed.  His  view  as  to  the  absurdity  of  the  membrana  tympani  se- 
cundaria being  a  transmitter  of  sound  waves  to  the  cochlea  agrees  with  my  own,  as  advo- 
cated above.  He  seems  also  to  favor  the  theory  that  the  basilar  membrane  is  the  true 
vibrating  medium,  which  carries  to  the  auditory  nerve  the  appreciation  of  the  note 
sounded,  rather  than  the  "  organ  of  Corti." 


458 


THE  CRANIAL  NERVES. 


tell  you  that,  when  the  attack  commenced,  everything  began 
to  whirl,  or  possibly  appeared  to  be  moving  toward  one  side  ; 
that  his  gait  became  unsteady,  and,  if  walking  was  possible, 
that  he  reeled  and  staggered  ;  while,  in  some  severe  cases,  the 
patient  feels  unsafe  even  when  lying  upon  a  bed  or  sofa,  and 
may  be  obliged  to  grasp  the  sides  of  the  couch  to  protect  him- 


Fia.  126. — Right  mcmhrana  tympani^  seen  from  within.    From  a  photography  and  somewhat 

reduced.     (Riidinger.) 

1,  head  of  the  malleus,  divided;  2,  neck  of  the  malleus ;  3,  handle  of  the  malleus,  with 
the. tendon  of  the  tensor  tympani  muscle  ;  4,  divided  tendon  of  the  tensor  tympani ; 
5,  6,  portion  of  the  malleus  between  the  layers  of  the  merabrana  tympani ;  7,  outer 
(radiating)  and  inner  (circular)  fibers  of  the  raembrana  tympani ;  8,  fibrous  nng  of 
the  membrana  tympani ;  9,  14,  15,  dcntoted  fibers,  discovered  by  Gruber ;  10,  poste- 
rior pocket;  11,  connection  of  the  posterior  pocket  with  the  malleus;  12,  anterior 
pocket;  13,  chorda  tympani  nerve. 

self  from  a  sensation  of  falling.  In  many  cases,  these  symp- 
toms are  markedly  intensified  bj/  movement  of  the  head.,  and, 
in  some  instances,  such  movements  often  tend  to  bring  about 
an  attack.*    The  patient  is  usually  pale  and  haggard,  some- 

'  Buzzard,  "Lancet,"  March  4,  1876. 


MBN'IEEB'S  DISEASE.  459 

times  perspires  freely,  and  often  vomits,'  while ^am  within 
the  head  is  a  symptom  which  not  infrequently  accompanies 
such  an  attack.  The  extent  to  which  this  type  of  vertigo 
may  be  manifested  varies  from  an  attack  of  but  momentary 
duration,  where  the  patient  can  retain  his  feet,  to  thof^e  severe 
forms  of  the  disease  where  the  attack  is  accompanied  by  a 
loss  of  consciousness,  which  may  remain  for  some  hours,  and 
resemble  the  condition  of  epileptic  vertigo. 

There  seems  to  be  little  doubt  that,  in  these  cases,  the  at- 
tack is  always  preceded  or  followed  by  some  abnormal  con- 
dition of  the  ear,  and  that  this  diseased  condition  was  the 
starting-point  of  the  vertigo."  Sometimes  the  patient  has 
long  been  deaf  in  one  ear,  or  a  condition  of  deafness  may 
follow  the  first  attack  of  vertigo ;  again,  the  approach  of  an 
attack  of  vertigo  may  be  told  by  the  occurrence  of  noises 
within  the  ear  of  one  side,  while,  in  some  cases,  there  exists 
a  constant  noise  within  the  ear,  which  increases  as  the  attack 
of  vertigo  is  imminent. 

It  is  often  extremely  difficult  to  persuade  a  patient,  suffer- 
ing from  this  affection,  that  the  attack  is  not  dependent  upon 
a  disordered  state  of  the  digestim  apparatus,  and  especially  is 
this  the  case  when  the  ear  trouble  is  of  old  standing,  or  when 
the  patient  is  unconscious  of  any  defect  in  his  hearing,  which 
is  by  no  means  an  unusual  occurrence.  Such  patients  are 
better  satisfied  if  the  attack  be  attributed  to  the  liver,  dys- 
pepsia, or  nervousness.  I  quote  the  following  sentence  from 
Hughlings- Jackson '  as  evidence  that  this  difficulty  is  met 
with  even  among  the  most  enlightened  of  the  community. 
He  says :  "  Even  medical  men,  who  have  aural  disease,  often 
totally  reject  the  proffered  explanation  of  their  attacks  of 
vertigo  ;   many  of  them  ascribe  their  ailment  to  digestive 

1  Ferrier,  "  Vomiting  in  connection  with  cerebral  disease,"  "  Brain,"  July,  1870. 

2  The  occurrence  of  vertigo  and  interference  with  coordination  is  not  alone  produced 
by  local  disease  of  the  ear,  even  when  associated  with  impairment  of  hearing.  It  may 
indicate  disease  of  the  cerebellum  or  of  the  medulla  oblongata,  which  creates  irritation  of 
or  some  interference  with  the  auditory  nucleus.  For  the  clinical  facts  pertaining  to  this 
symptom,  the  reader  is  referred  to  previous  pages  of  this  volume. 

3  Hughlings-Jackson,  "Lancet,"  March  11,  18*76;  same  author,  "Lancet,"  March  11, 
1876;  Gowers,  "Lancet,"  March,  October,  1880. 


460 


TEE  CRANIAL  NERVES. 


troubles.     A  medical  man  had  deafness  in  his  left  ear,  with 
occasional  slight  vertigo.     One  day,  while  walking  in  his  gar- 


FiQ.  127. — Section  of  tke  first  turn  of  the  spiral  canal  of  a  cat  newli/-bom. — Section  of  the 
cochlea  of  a  human  foetits  at  the  fourth  month.  From  a  pJiotograph^  and  someichai 
reduced.     (Riidinger.) 

Upper  figure:  1,  2,  6,  lamina  spiralis;  2,  lower  plate;  3,  4,  5,  5,  nervus  cochlearis ;  7, 
membrane  of  Reissner  ;  8,  membrana  tcctoria  :  9,  epithelium  ;  10, 11,  pillars  of  Corti ; 
12,  inner  hair  cells;  13,  outer  hair  cells;  14,  16,  membrana  basiiaris;  15,  epithe- 
lium in  the  sulcus  spiralis;  17,  18,  19,  ligamentum  spirale ;  20,  spiral  canal  below 
the  membrana  basiiaris. 

Lower  figure  :  S  T,  S  T,  6,  5,  7,  7,  8,  8,  scala  tympani ;  S  V,  S  V,  9,  9,  scala  vestibuli  ;  1, 
base  of  the  cochlea  ;  2,  apex  ;  3,  4,  central  column ;  10,  10,  10,  10,  ductus  cochlearis ; 
11,  branches  of  the  nervus  cochlearis;  12, 12, 12,  spiral  ganglion ;  13,  14,  limbus  lami- 
nae spiralis ;  16,  membrane  of  Reissner  ;  16,  epithelium  ;  17,  outer  hair  cells  ;  18,  epi- 
thelium of  the  membrana  basiiaris ;  19,  nervous  filaments ;  20,  union  of  the  membrana 
basiiaris  with  the  ligamentum  spirale  ;  21,  epithelium  of  the  peripheral  wall  of  the 
ductus  cochlearis  ;  22,  23,  membrana  tectoria  ;  24,  spiral  canal  below  the  membrana 
basiiaris. 


FUNCTION  OF  SEMICIRCULAR   CANALS.  4G1 

den,  he  had  a  pain  in  his  head,  was  very  giddy,  fell  in  the 
shrubs,  and  vomited.  This  was  plainly  ear  vertigo,  as  he 
himself  knew.  But  he  had  the  following  diagnoses  made  of 
his  case  by  other  medical  men :  1,  nothing  ;  2,  nervousness ; 
3,  deranged  stomach." 

That  some  persons  who  are  deaf  in  one  ear  are  absolutely 
unconscious  of  it  is  too  often  noticed  to  be  now  disputed. 
Gowers '  lays  stress  upon  this  point  in  the  following  words : 
"The  fact  that  the  patient  may  be  unconscious  of  a  most  sig- 
nificant auditory  defect  lessens  the  value  of  former  observa- 
tions as  evidence  of  the  definite  character  of  stomachal  ver- 
tigo. My  own  conviction  is  that,  in  the  vast  majority  of 
cases  in  which  a  vertigo  of  definite  and  uniform  character  is 
apparently  excited  by  gastric  disturbance,  an  auditory  defect 
will  be  discovered  on  careful  examination." 

Patients  afflicted  with  diseases  of  the  ear  may,  in  some 
cases,  make  themselves  dizzy  by  pressure  upon  the  ear  of  the 
affected  side  ; ""  while  oscillatory  movements  of  tlie  eyes  may 
occasionally  accompany  the  vertigo  dependent  upon  disease 
of  the  acoustic  apparatus. 

It  is  well  known  that  the  semicircular  canals  within  the 
temporal  bone,  when  diseased,  are  liable  to  create  the  so-called 
Meniere's  malady,  in  which  constant  vertigo  is  a  prominent 
symptom  ;  and  experiments  upon  birds  and  animals '  seem  to 
show  that,  in  some  unknown  way,  these  canals  affect  coordi- 
nation of  movement  and  tend  to  preserve  the  equilibrium  of 
the  body. 

When  the  horizontal  canal  of  the  bird  is  cut,  the  head  is 
constantly  moved  from  side  to  side  ;  when  the  posterior  verti- 
cal canal  is  cut,  the  head  is  moved  up  and  down  ;  when  the 
anterior  vertical  canal  is  severed,  the  movement  of  the  head 
is  in  a  diagonal  direction.  If  section  of  either  of  these  canals 
be  made,  upon  both  sides  of  the  head,  the  movements  of  the 
head  above  described  are  permanent ;  but,  if  made  on  one 

^  "Brit.  Med.  Jour.,"  April,  187Y. 
2  Schwaback,  as  quoted  by  Hughlings-Jackson. 

^Flourens,  1824;  Crum  Brown,  "Jour.  Anat.  Phys.,"  18'74;  Cyon,  "Th^se  pour  le 
doctorat  in  medicine,"  as  quoted  by  Foster. 


462  THE  CRANIAL  NERVES. 

side  only,  they  tend  to  disappear  within  twenty-four  or  forty- 
eight  hours. '  If  the  same  class  of  experiments  be  made  upon 
i-abbits,  the  movements  of  the  head  are  less  marked,  but  oscil- 
lating movements  of  the  eyeballs  (nystagmus)  are  developed  ; 
while,  if  made  upon  certain  other  animals,  a  loss  of  coordina- 
tion in  the  movements  of  the  body  and  limbs  is  sometimes 
produced." 

When  a  person  is  rotated  for  some  time,  a  sense  of  vertigo 
is  produced ;  and  this  symptom  seems  to  warrant  the  supposi- 
tion that  some  abnormal  effect  is  produced  within  the  semicir- 
cular canals,  through  the  auditory  nerve  filaments,  possibly 
as  a  result  of  concussion  of  the  fluids  of  the  ear  against  the  ] 
bony  wall.' 

The  following  quotation  from  Michael  Foster,*  in  discuss- 
ing the  different  theories  advanced  to  explain  coordination  of 
movement  and  the  various  reflex  phenomena  which  are  con- 
stantly brought  to  the  notice  of  the  physiologist,  seems  par- 
ticularly applicable  to  the  practical  branches  of  medicine : 
"All  day  long,  and  every  day,  multitudinous  afferent  im- 
pulses, from  eye  and  ear,  and  skin  and  muscle,  and  other 
tissues  and  organs,  are  streaming  into  our  nervous  system, 
and,  did  each  afferent  impulse  produce  its  correlative  motor 
impulse,  our  life  would  be  a  prolonged  convulsion.     As  it  is, 

^  E.  Cyon,  o;>.  ciV.,  1878. 

*  The  experiments  of  Arthur  Bottcher,  made  in  1872,  seem  to  conflict  with  those  of 
Cyon,  Goltz,  and  Flourens,  as  to  the  function  of  the  semicircular  canals.  He  claims  that 
the  section  of  either  canal  can  be  made  without  causing  any  symptoms  of  incoordination, 
provided  the  auditory  nerve  filaments  are  not  pulled  upon.  The  fact  that  the  auditory 
nerve  is  not  bound  down  at  any  point  between  the  brain  and  the  labyrinth  explains,  ac- 
cording  to  this  observer,  why  the  slightest  traction  upon  it  may  injure  its  attachment  to 
the  medulla,  and  thus  create  the  symptoms  described  by  Cyon,  Goltz,  and  Flourens. 

'  A.  H.  Buck,  in  a  late  treatise,  reiterates  his  former  statement,  that  nerves  are  not 
found  in  the  semicircular  canals,  except  in  the  ampullae.  This  fact  he  adduces  in  sup- 
port of  the  theory  that  they  have  no  relation  to  the  perception  of  sound  impulses.  He 
also  claims  that  the  small  size  of  this  portion  of  the  membranous  labyrinth,  as  compared 
with  the  diameter  of  the  bony  excavation,  coupled  with  the  peculiar  reticulated  arrange- 
ment which  exists  in  the  space  between  the  membranous  tube  and  the  bony  wall,  further 
sustains  his  objection.  This  author  seems  to  claim  that  the  semicircular  canals  act  as  a 
means  of  relief  to  extreme  intra-cochlear  pressure.  Certainly,  more  light  is  needed  upon 
the  construction  of  this  portion  of  the  internal  ear,  before  its  function  can  be  positively 
determined. 

*  Op.  cit. 


FUNCTION  OF  TEE  TYMPANIC  MU8CIES.  463 

by  the  checks  and  counter-checks  of  cerebral  and  spinal  activ- 
ities, all  these  impulses  are  drilled  and  marshaled,  and  kept 
in  hand,  in  orderly  array,  till  a  movement  is  called  for ;  and 
thus  we  are  able  to  execute  at  will  the  most  complex  bodily 
manoeuvres,  knowing  only  why,  and  unconscious,  or  btit  dimly 
conscious,  how  we  carry  them  out." 

The  tensor  tympani  muscle,  which  has  previously  been 
mentioned  as  deriving  its  motor  power  from  the  fifth  nerve 
and  otic  ganglion,  is  of  use,  even  in  the  quiescent  state,  in 
preventing  the  membrana  tympani  from  being  pushed  too  far 
outward.  During  its  contraction,  the  membranous  drum  of 
the  ear  is  made  tense,  for  the  purpose  of  deadening  some 
sounds  or  of  favoring  the  reception  of  others,  by  bringing  the 
tension  of  the  membrane  in  more  perfect  attune  to  the  sounds 
which  fall  upon  it.  It  may,  therefore,  be  considered  in  some 
respects  as  an  analogue  to  the  ciliary  muscle  of  the  eye, 
since  both  act  as  a  sort  of  accommodation  to  a  mechanism. 
In  some  persons,  this  muscle  is  under  voluntary  control,  and 
thus  a  crackling  sound  may  be  produced  within  the  ear  at 
will,  or  discords  be  produced  when  musical  sounds  are  being 
listened  to. 

The  stapedius  muscle,  which  derives  its  motor  power  from 
the  facial  nerve,  is  supposed  to  regulate  the  movements  of  the 
stapes  (one  of  the  small  bones  of  the  middle  ear),  and  espe- 
cially to  prevent  any  sudden  or  excessive  movement  of  the 
membrana  tympani  from  forcing  its  base  too  far  into  the 
fenestra  ovalis. 

The  Eustachian  tube  is  unquestionably  open  during  the 
act  of  swallowing,  but  it  is  still  disputed  whether  it  remains 
permanently  open  or  is  open  at  intervals.  The  swelling  of 
the  mucous  membrane  which  lines  the  tube,  in  catarrhal 
inflammation,  interferes  with  the  entrance  of  air  into  the 
middle  ear,  and  is  frequently  associated  with  that  peculiar 
ringing  or  buzzing  in  the  ear  so  often  present  during  attacks 
of  influenza.  One  of  the  functions  of  this  tube  is  undoubtedly 
to  afford  a  means  of  exit  for  the  secretions  of  the  cavity  of 
the  middle  ear,  and,  in  case  of  inflammation  of  that  cavity, 


464  THE  CRANIAL  NERVES.  \ 

i 

should  the  Eustachain  tube  become  closed,  perforation  of  the 
drum  will  ensue,  when  the  presence  of  the  accumulated  pus  i 
creates  imperfect  nutrition  of  that  membrane  and  consequent  ; 
ulceration  of  its  coats.  I 

Waves  of  sound  can  and  do  reach  the  endolymph  of  the  j 
internal  ear  by  direct  conduction  through  the  skull.  Since,  j 
however,  sonorous  vibrations  are  transmitted  from  the  air  to  | 
solids  and  liquids  (and  most  sounds  come  to  us  through  the  < 
air),  some  special  apparatus  is  required  to  thus  transfer  the  ; 
aerial  vibrations  to  the  fluids  of  the  labyrinth.  The  late  me-  \ 
chanical  devices,  recommended  for  the  relief  of  perfect  deaf-  j 
ness,  in  which  the  teeth  are  used  as  a  conducting  medium,  ; 
have  not  as  yet  fulfilled  the  predictions  of  their  inventors. '        ; 

The  deafness  which  often  follows  suppuration  of  the  mid-  i 
die  ear  does  not  necessarily  indicate  any  diseased  condition 
of  the  auditory  nerve,  since  it  may  be  the  result  of  perfora- 
tion of  the  membrana  tympani^^  or  of  an  abnormal  condition  { 
of  the  hones  of  the  middle  ear^  both  of  which  might  interfere  ] 
most  seriously  with  the  transmission  of  sound.  \ 

Foreign  bodies  in  the  ear  often  create  most  alarming  'i 
symptoms  ;  and  even  an  accumulation  of  wax,  pressing  on  the  \ 
drum,  may  create  a  mental  condition  strongly  resembling  the  ; 
excitement  of  alcohol  or  mania.'  Even  syringing  the  ear  has 
been  known  to  produce  fainting  and  severe  attack  of  audi-  ; 
tory  vertigo.  Prolonged  suppuration  pf  the  middle  ear  may  i 
be  the  direct  cause  of  fatal  inflammation  of  the  meninges  of  ; 
the  brain.  j 

Neuroses  of  the  acoustic  nerve  are,  of  necessity,  more  ob- 
scure and  difficult  of  detection  than  those  of  the  other  special 

*  It  has  long  been  the  custom  with  otologists  to  use  a  tuning-fork,  placed  upon  the 
forehead  (when  in  vibration),  to  determine  between  disease  of  the  middle  ear  and  that  of 
the  labyrinth ;  since  in  the  former  the  affected  ear  hears  the  tuning-fork  most  plainly, 
while,  in  the  latter,  the  unaffected  ear  hears  it  most  distinctly. 

'  Perforation  of  the  external  drum  of  the  ear  does  not  necessarily  create  deafness. 
That  remarkable  case,  reported  by  Sir  Astley  Cooper,  when  both  drums  were  nearly  de- 
stroyed and  where  the  patient  could  still  hear  ordinary  conversation,  illustrates  this 
point. 

'  See  case  of  a  louse  in  the  ear,  reported  by  Hughlings-Jackson,  "  Lancet,"  October, 
1880. 


NEUROSES   OF  THE  AUDITORY  NERVE.  465 

senses ;  since  the  tests  of  normal  sight,  smell,  and  taste  are 
much  more  easy  and  satisfactory  than  the  appreciation  of  the 
faculty  of  a  fine  discrimination  on  the  part  of  the  patient  be- 
tween notes  of  a  different  pitch  and  quality.  To  what  extent 
the  original  and  exhaustive  researches  of  Brenner,'  as  to  the 
value  of  the  galvanic  current  in  the  diagnosis  of  abnormal  con- 
ditions of  the  nerve  filaments  within  the  chambers  of  the  laby- 
rinth, will  be  sustained  by  pathological  and  clinical  investiga- 
tion, it  is  difficult  now  to  say  ;  but  it  certainly  appears  to  shed 
some  light  upon  a  field  of  diagnosis  which  has  been  almost 
unexplored  on  account  of  the  difiiculties  which  have  hitherto 
existed.  It  will  exceed  the  scope  of  this  volume  to  enter  into 
the  detail  of  this  new  method,  since  the  principles  of  the 
manifestation  of  the  electric  current  upon  nerve  tissue  would 
have  to  be  explained,  and  the  different  formulae  of  nerve  reac- 
tion given.  It  can,  however,  be  stated  that  the  principle  con- 
sists of  obtaining  certain  sensations  by  means  of  the  auditory- 
nerve  filaments,  when  one  moistened  pole  of  an  electric  bat- 
tery is  placed  upon  the  tragus  or  the  auditory  meatus,  and 
the  other  to  the  back  of  the  neck  or  the  inner  side  of  the 
arm,  and  the  intensity  of  the  current  regulated  by  means  of 
the  rheostat.'*  By  this  means  the  condition  of  acoustic  hyper- 
sesthesia  and  of  anaesthesia  may  be  detected  with  an  accuracy 
which  older  methods  could  not  afford. 

The  state  of  acoustic  hyper cBsthesia  may  be  of  central 
origin  or  dependent  upon  some  peripheral  cause.  If  due  to 
the  former,  it  may  be  developed  in  connection  with  chronic 
cephalalgia,  hysteria,  insanity,  cerebral  hypersemia,  and  with 
irritative  conditions  of  the  brain  or  spinal  cord.  It  is  some- 
times associated  with  hallucinations  of  hearing,  especially 
if  present  as  a  complication  of  insanity.  The  peripheral 
causes  of  this  condition  comprise  anything  which  can  pro- 
duce an  exaggeration  of  the  tension  of  the  muscles  or  bones 
of  the  middle  ear,  thus  resulting  in  a  constant  compression 
of  the  internal  structures  of  the  labyrinth.  The  experi- 
ments of  Lucae  seem  to  point  to  the  tensor  tympani  mus- 

*  As  discussed  in  detail  by  Erb,  Rosenthal,  and  others.  ^  Erb's  rule. 


466  THE  CRANIAL  NERVES. 

die  as  the  agent  in  accommodating  the  bones  of  the  middle 
ear  to  the  keenest  appreciation  of  musical  tones.,  while  the 
stapedius  muscle  presides  over  the  accommodation  for  shriller 
and  non-musical  auditory  sensations.  We  can  thus  under- 
stand, if  this  be  true,  how  paralysis  of  the  stapedius  muscle 
would  create  an  hypersesthesia  of  the  acoustic  apparatus,  and, 
as  this  muscle  may  be  affected  in  facial  paralysis,  how  all  of 
the  causes  of  that  condition  may  be  the  exciting  causes  also 
of  this  affection  of  the  ear.'  , 

The  state  of  anmsthesia  of  the  auditory  nerve  is  always 
associated  with  some  severe  and  persistent  defect  in  hearing, 
since  the  filaments  of  the  auditory  nerve  are  no  longer  able  to 
transmit  the  impressions  of  sound.  Its  causes  are  but  poorly 
understood,  but  it  seems  positive  that  lesions  of  the  posterior 
regions  of  the  meso-cephalon,  the  medulla,  and  cerebellum,  as 
well  as  new  growths  at  the  base  of  the  brain,  excessive  intra- 
cranial pressure,  and  local  disease  of  the  labyrinth  itself,  may 
be  thus  manifested.  The  deafness  which  follows  the  exan- 
thematous  fevers,  and  is  observed  in  hysteria  and  ataxia, 
usually  indicates  changes  in  the  meninges  of  the  brain,  which, 
if  severe,  produce  an  incurable  loss  of  hearing.  Malforma- 
tions of  the  internal  or  middle  ear,  either  congenital,  or  ac- 
quired during  childhood  after  cerebral  diseases,  are  the  com- 
mon causes  of  deaf-mutism. 

THE  GLOSSO-PHARYNGEAL,   OR  NINTH  NERVE. 

Like  the  two  previous  nerves,  both  the  superficial  and 
deep  points  of  origin  of  the  glosso-pharyngeal  nerve  are  situ- 
ated in  the  medulla  oblongata,  a  separate  gray  nucleus  in  the 
fioor  of  the  fourth  nentricle  being  ascribed  to  it.'  This  nerve 
escapes  from  a  groove  between  the  lateral  tract  and  the  resti- 
form  body  of  the  medulla,  lying  below  the  auditory  nerve 
and  above  the  pneumogastric,  and  passes  out  of  the  cavity  of 

^  This  may  be  deemed  incompatible  with  statements  made  on  page  440  of  this  vol- 
ume, as  the  tensor  tympani  muscle  was  there  stated  to  be  an  agent  in  creating  auditory 
defect  in  Bell's  paralysis. 

*  See  previous  page  in  this  section,  in  which  its  deep  origin  is  discussed. 


THE   GL08S0-PHARYNGEAL,   OR  NINTH  NERVE.        467 

the  cranium  by  the  jugular  foramen,  where  it  lies  in  close 
relation  with  the  pneumogastric  and  spinal  accessory  nerves, 
the  jugular  vein,  and  the  inferior  meningeal  artery.  It  pos- 
sesses motor  and  sensory  fibers,  and  fibers  which  assist  in 
the  appreciation  of  the  special  sense  of  taste. 


Fig.  128. —  Glosso-pharyngeal  nerve.      (Sappey.) 

1,  large  root  of  the  fifth  nerve  ;  2,  ganglion  of  Gasser  ;  3,  ophthalmic  division  of  the  fifth  ; 
4,  superior  maxillary  division ;  5,  inferior  maxillary  division ;  6,  10,  lingual  branch 
of  the  fifth,  containing  the  filaments  of  the  chorda  tympani;  1,  branch  from  the  sub- 
lingual to  the  lingual  branch  of  the  fifth ;  8,  chorda  tympani ;  9,  inferior  dental 
nerve;  10,  terminal  filaments  of  the  lingual  nerve;  11,  submaxillary  ganglion ;  12, 
mylo-hyoid  branch  of  the  inferior  dental  nerve;  13,  anterior  belly  of  the  digastric 
muscle;  14,  section  of  the  mylo-hyoid  muscle;  15,  18,  glosso-pharyngeal  nerve;  16, 
ganglion  of  Andersch  ;  17,  branches  from  the  glosso-pharyngeal  to  the  stylo-glossus 
and  the  stylo-pharyngeus  muscles;  19,  19,  pneumogastric;  20,  21,  ganglia  of  the 
pneumogastric ;  22,  22,  superior  laryngeal  nerve ;  23,  spinal  accessory ;  24,  25,  26, 
27,  28,  sublingual  nerve  and  branches. 

By  reference  to  the  diagram,'  it  will  be  perceived  that  two 
ganglioform  enlargements  are  developed  upon  this  nerve,  the 
upper  one  being  situated  on  a  level  of  the  upper  opening  of 

1  See  Fig.  129,  on  the  following  page. 


468 


THE  CRANIAL  NERVES, 


I 


the  jugular  foramen,  while  the  lower  one  lies  slightly  below  the 

foramen.  To  the  first,  the  name 
''  jugular  ganglion  "  is  ap- 
plied, while  the  second  is  called 
the  ''^ganglion  of  AnderscJi,''^ 
after  its  discoverer.  These  two 
ganglia  do  not  include  the  same 
relative  proportion  of  nerve  fibers 
derived  from  the  glosso-pharyn- 
geal,  since  the  jugular  ganglion 
is  developed  upon  only  a  por- 
tion of  the  nerve,  while  the 
ganglion  of  Andersch  includes 
all  the  filaments  of  the  trunk  of 
that  nerve. 

Within  the  jugular  foramen, 
the  glosso-pharyngeal  nerve  lies 
in  front  of  the  spinal  accessory 
and  pneumogastric  nerves,  which 
are  separated  from  it  by  a  sheath 
which  invests  the  two  latter,  and 
it  bears  an  intimate  relation  with 
the  jugular  vein  within  the  fora- 
men, and  also  in  the  neck. 

As  a  motor  nerve^^  the  glosso- 
pharyngeal supplies  the  levator 
palati,  azygos  uvulae,'  stylo- 
pharyngeus,  and  the  middle 
constrictor  of  the  pharynx; 
while,  as  a  nerve  of  general  sen- 

'  It  is  extremely  doubtful  if  the  glosso- 
pharyngeal nerve  possesses  any  motor  fibers 
which  are  not  derived  from  other  nerves  by 
filaments  of  comrauni cation. 

^  These  muscles,  if  supplied  by  this  nerve 
(as  experiments  seem  to  show),  are  reached 
by  fibers  sent  to  the  facial  nerve,  and  after- 
ward, by  means  of  the  great  petrosal  branch, 
to  Meckel's  ganglion. 


Fio.  129. — A  diagram  of  the  branches  of 
the  ninth  cranial  or  glosso-pharyn- 
geal nei've. 

1,  filaments  of  origin,  extending  into 
the  medulla  oblongata ;  2,  the  jug- 
vlar  foramen^  through  which  the 
nerve  escapes  from  the  cranium ; 
8,  the  jiigular  ganglion^  developed 
upon  the  nerve  in  the  jugular  fora- 
men ;  4,  the  ganglion  of  Andersch^ 
or  the  *''' petrous  ganglion  "/  6,  the 
auricular  branch,  deriving  a  fila- 
ment also  from  the  pneumogastric 
nerve ;  6,  a  communicating  branch 
to  the  pneumogastric  nerve;  7,  a 
communtcating  branch  to  the  sym- 
pathetic nerve;  8,  the  tympanic 
branch  or  "  Jacobsoti's  nerve,^^  dis- 
tributed to  the  middle  ear;  9,  a 
communicating  branch  to  the  carot- 
id plexus  of  the  sympathetic ;  10, 
the  tonsillar  branches,  distributed 
to  the  tonsil ;  11,  a  portion  of  the 
pharyngcid  plexus,  formed  also  by 
the  pneumogastric  nerve;  12,  the 
linptal  brandies,  distributed  to  the 
mucous  membrane  and  the  papillae 
of  the  base  and  sides  of  the  tongue. 


1 


DISTRIBUTION   OF  GL0S80-PHARYNGEAL  NERVE.       469 

sation^  it  supplies  the  root  of  the  tongue,  the  soft  palate,  the 
pharynx,  the  Eustachian  tube,  and  the  tympanum.  It  will  be 
thus  perceived  that  the  glosso-pharyngeal  nerve  possesses, 


Fig.  130. — Papillm  of  the  tongue.    (Sappey.) 

1,  1,  circumvallate  papillae;  2,  median  circuravallate  papilla,  which  entirely  fills  the  fora- 
men caecum ;  3,  3,  3,  3,  fungiform  papillae  ;  4,  4,  filiform  papillae ;  5,  5,  vertical 
folds  and  furrows  of  the  border  of  the  tongue  ;  6,  6,  6,  6,  glands  at  the  base  of  the 
tongue ;  7,  7,  tonsils ;  8,  epiglottis  ;  9,  median  glosso-epiglottidean  fold. 

within  itself^  all  the  necessary  fibers  to  insure  those  succes- 
sive acts  of  a  reflex  type  which  occur  during   deglutition,' 

^  It  is  denied  by  some  physiologists  that  the  sensory  filaments,  which  are  the  main 
agents  in  exciting  the  reflex  acts  perceived  during  deglutition,  are  those  of  the  glosso- 
pharyngeal nerve ;  since  the  sensory  filaments  of  the  fifth  nerve  distributed  to  the  palate 
and  pharynx  from  Meckel's  ganglion  seem  to  also  fulfill  that  important  function. 


470 


THE  CRANIAL  NERVES. 


and  it  is  by  this  nerve  that  the  second  act  of  deglutition  is 
chiefly  excited  and  performed. 

The  sense  of  taste,  which  is  afforded  by  the  glosso-pharyn- 
geal,  is  confined  to  the  posterior  third  of  the  tongue.  A  sim- 
ilar distribution  of  its  sensory  fibers  is  remarkably  illustrated 
in  that  case  of  Hilton's/  where  an  attack  of  tonsillitis  pro- 
duced a  sympathetic  furring  of  the  posterior  third  only  of 
the  lateral  half  of  the  tongue. 

Though  analogy  would  lead  us  to  suppose  that  a  stimulus 
applied  to  any  part  of  the  course  of  the  gustatory  fibers  of  the 
glosso-pharyngeal  nerve  would  give  rise  to  a  sensation  of 
taste  and  nothing  else,  the  proof  is  not  forthcoming;  since 
this  nerve,  as  before  stated,  is  a  mixed  nerve  containing  sen- 
sory fibers  as  well  as  those  of  taste. 


Fig.  131.  Fig.  132. 

Varieties  of  papillce  of  the  tongtie.     (Sappey.) 

Fig.  131.— Medium-sized  circumvallate  papilla:  1,  papilla,  the  base  only  being  apparent : 
it  is  seen  that  the  base  is  covered  with  secondary  papillae ;  2,  groove  between  the 
papilla  and  the  surrounding  wall ;  3,  3,  wall  of  the  papilla. 

Fig.  132.— Fungiform,  filiform,  and  hemispherical  papillae :  1,  1,  two  fungiform  papillae, 
covered  with  secondary  papillae ;  2,  2,  2,  filiform  papillae ;  3,  a  filiform  papilla,  the 
prolongations  of  which  are  turned  outward ;  4,  a  filiform  papilla,  with  vertical  pro- 
longations ;  5,  5,  small  filiform  papillae,  with  the  prolongations  turned  inward ;  6,  6, 
filiform  papillae,  with  striations  at  their  bases ;  7,  7,  hemispherical  papillae,  slightly 
apparent,  situated  between  the  fungiform  and  the  filiform  papillae. 

Bitter  substances  are  most  tasted  upon  the  hack  of  the  \ 
tongue,  and  sweet  substances  when  placed  upon  the  tipi^  % 
a  point  not  without  value  in  administering  medicines.     The  i 

'  "  Rest  and  Pain."    For  similar  effects  due  to  the  fifth  nerve,  see  a  previous  lecture^     .-a 
^  Mich.  Foster,  op  cit. 


FUNCTIONS  OF  GLOSSO-PEARYNOEAL  NERVE.         471 

so-called  ''gustatory  buds,"  which  by  some  have  been  re- 
garded as  specific  organs  of  taste,  are  found  also  upon  the 
epiglottis,  which  is  wholly  devoid  of  taste  ;  hence  their  func- 
tion can  not  as  yet  be  considered  as  fully  determined. 

As  a  means  of  refreshing  your  memory,  the  following 
classification  of  the  branches  of  the  glosso-pharyngeal  nerve 
may  prove  of  value.  It  will  be  seen  that  the  tympanic  branch, 
or  Jacobson's  nerve,  is  specially  important,  since  it  supplies 
portions  of  the  middle  ear  which  have  been  studied,  when  the 
auditory  nerve  was  discussed,  in  their  relation  to  the  mechan- 
ism of  hearing ;  and  also  because  it  gives  a  filament  to  two 
of  the  petrosal  nerves,  whose  functions  have  been  considered 
in  connection  with  the  seventh  cranial  nerve.* 


A  TABLE   OF  THE   BKANCHES   OF  THE   GLOSSO-PHAKYKGEAL  NERVE 
AND   THEIR   DISTRIBUTION.'' 


Glosso-pharyngeal 

(Ninth  Cranial) 

Nerve. 


1.  Tympanic  branch,  or 
Jacobson's  nerve. 


Communicating  /Large  petrosal  nerve, 

filaments  to  ^ig^^«,VP^^"J' 

(^  bmall  petrosal  nerve. 

Branches  of     /fenestra  ovalis 
disirihution  to   1  l^^f^'^.  rotunda, 
(^  Jiiustachian  tube. 

2.  Carotid  branches. 

3.  Pharyngeal  branches  (help  to  form  the  pharyngeal  plexus). 

4.  Muscular  branches  (to  muscles  of  the  pharynx). 

5.  Tonsillar  branches  (help  to  form  the  tonsillar  plexus). 
^  6.  Lingual  branches. 


EFFECTS   OF   SECTION. 

Section  of  the  glosso-pharyngeal  nerve  is  followed  by  a  type 
of  paralysis,  in  which  deglutition  becomes  an  act  of  extreme 
difficulty,  and  in  which  regurgitation  of  food  into  the  nostril 
is  particularly  liable  to  occur.  The  sense  of  taste  in  the  pos- 
terior third  of  the  tongue  is  furthermore  completely  destroyed, 
thus  tending  to  prove  that  the  gustatory  fibers  are  inherent  to 
the  nerve  itself,  and  not  the  result  of  a  communication  between 

^  Flint  ascribes  to  the  chorda  tympani  nerve  the  ability  to  perceive  only  saline,  add, 
and  styptic  qualities ;  and  to  the  glosso-pharyngeal  nerve,  the  appreciation  of  sweet,  alka- 
line, hitter,  and  metallic  tastes.  Jacobson's  nerve  probably  controls  the  flow  of  saliva ; 
acting  in  concert  with  the  chorda  tympani  branch  of  the  facial  nerve. 

'^  Copied  from  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney).  Putnam's  Sons, 
New  York,  1880. 


472 


THE  CRANIAL  NERVES, 


it  and  some  other  nerve,  as  is  claimed  in  reference  to  tlie  gus- 
tatory fibers  of  the  fifth. ' 

It  is  stated,  by  some  of  the  later  investigators  upon  this 
subject,  that  the  sense  of  taste  is  not  alone  confined  to  the 
tongue,  but  exists  also  in  the  pillars  of  the  fauces  and  the 
walls  of  the  pharynx,  and  that  section  of  the  glosso-pharyn- 
geal  nerve  causes  an  entire  abolition  of  this  power  of  special 
sense  in  these  latter  regions,  as  well  as  in  the  posterior  third 
of  the  tongue.' 

THE  ACT   OF  DEGLUTITION  AND  ITS  MECHANISM. 

The  act  of  deglutition  is,  perhaps,  more  properly  con- 
nected with  the  glosso-pharyngeal  nerve  than  with  any  other, 
although  that  nerve  assists  in  the  performance  of  one  stage 
only  of  the  entire  act.  For  convenience  of  description,  it  has 
been  the  custom  of  physiologists  to  divide  the  act  of  degluti- 
tion into  three  distinct  periods.     The  first  period,  comprising 


Fig.  us.— Taste  htda  from  the  lateral  taste  organ  of  the  rabbit.    (Engelmann.) 

the  passage  of  the  bolus  of  food  through  the  mouth,  which  is 
under  the  control  of  the  voluntary  muscles  ;  the  second,  the 
passage  of  the  bolus  through  the  isthmus  of  the  fauces  and 
the  pharynx  ;  the  third,  the  passage  through  the  oesophagus 
to  the  cavity  of  the  stomach. 

In  t\iQ  first  period,  the  food  is  first  seized  by  the  lips,  then 

*  See  previous  lecture  on  the  fifth  nerve,  and  also  the  lecture  upon  the  facial  nerve. 

*  Experiments  seem  to  point  to  the  fungiform  and  circumvallate  papillce  of  the  tongue 
as  the  chief  agents  in  perceiving  taste,  if  the  function  of  the  "  taste  buds  "  of  Low6n  and 
Schwalbe  are  accepted  as  proven.     See  Fig.  138. 


THE  PHYSIOLOGY  OF  DEGLUTITION.  473 

forced  between  the  jaws  by  the  tongue  and  the  buccinator 
muscles  ;  and  by  the  teeth  it  is  not  only  masticated, ,  but  is 
also  mixed  with  the  salivary  secretion.  When  the  food  is 
ready  to  be  swallowed,  the  mouth  is  first  closed,  as  the  act  is 
performed  with  extreme  difficulty  when  the  mouth  is  open,  be- 
cause the  tongue  can  not  properly  act  upon  the  bolus/  The 
tongue  now  becomes  widened,  so  as  to  offer  a  large  surface 
to  the  bolus  of  food,  and,  with  the  bolus  placed  behind  it,  is 
pressed  backward  along  the  roof  of  the  mouth.  In  case  the 
food  to  be  swallowed  happens  to  be  in  a  liquid  form,  the 
tongue  is  so  curved  that  its  edges  curl  upward,  while  its 
dorsum  is  depressed  in  the  center,  thus  forming  a  longitu- 
dinal groove  along  its  entire  length ;  and  the  soft  palate  is 
so  closely  applied  to  the  base  of  the  tongue  as  to  admit  of  a 
sucking  force. 

The  importance  of  the  tongue  during  this  period  of  the  act 
of  swallowing  can  not  be  overestimated.  Animals,  in  which 
the  tongue  has  been  paralyzed  by  section  of  the  nerves  of  that 
organ,  exhibit  the  utmost  distress  in  their  efforts  to  bring  the 
food  to  the  back  portion  of  the  mouth,  and  are  forced  to  so 
toss  the  head  as  to  bring  the  force  of  gravity  to  their  aid.' 
Drinking,  also,  becomes  even  more  interfered  with,  and  the 
tongue  is  no  longer  used  to  help  in  the  act ;  hence,  various 
devices  are  used  to  bring  the  fluid  where  the  reflex  act  of  the 
fauces  will  help  to  carry  it  to  the  stomach.  If  it  were  not  for 
the  fact  that,  after  removal  of  the  tongue  for  local  disease, 
the  stump  was  of  sufficient  length  to  be  of  great  assistance  in 
controlling  the  bolus  of  food,  such  an  operation  would  be  a 
questionable  procedure  in  surgery. 

It  may  be  noticed,  by  those  of  you  who  have  been  follow- 
ing these  remarks  with  care,  that  the  glosso-pharyngeal  nerve 
has,  as  yet,  had  no  influence  upon  the  mechanism  of  degluti- 
tion, since  the  buccinator  muscles  are  suppKed  by  the  facial 
nerve,  and  the  tongue  by  the  hypo-glossal  nerves,  which  have 

*  For  the  clinical  proof  of  this  fact,  the  reader  is  referred  to  the  effects  of  "  facial 
diplegia."     See  page  443. 

2  We  see  this  also  marked,  but  to  a  less  extent,  in  patients  afflicted  with  glosso-labial 
paralysis. 


474 


THE  CRANIAL  NERVES. 


not,  as  yet,  been  described  ;  but,  as  the  second  and  third 
periods  of  the  act  are  the  most  complex,  and  the  second  most 
completely  under  the  control  of  that  nerve,  the  omission  of 
the  mechanism  of  the  first  period,  until  the  whole  could  be 
considered  together,  was  for  the  purpose  of  making  the  sub- 


FiG.  134. — Cavities  of  the  mouth  and  pharynx,  etc.    (Sappey.) 

Section  in  the  median  line  of  the  face  and  the  superior  portion  of  the  neck,  designed  to 
show  the  mouth  in  its  relations  to  the  nasal  fossae,  the  pharj-nx,  and  the  larynx  :  1, 
sphenoidal  sinuses  ;  2,  internal  orifice  of  the  Eustachian  tube  ;  3,  palatine  arch ;  4, 
velum  pendulum  palati ;  5,  anterior  pillar  of  the  soft  palate ;  6,  posterior  pillar  of 
the  soft  palate  ;  7,  tonsil ;  8,  lingual  portion  of  the  cavity  of  the  pharynx  ;  9,  epi- 
glottis ;  10,  section  of  the  hyoid  bone ;  11,  laryngeal  portion  of  the  cavity  of  the 
pharynx ;   12,  cavity  of  the  larynx. 


ject  more  easy  of  comprehension  than  if  the  different  periods 
were  considered  separately  from  each  other.  The  effect  of 
section  of  the  inferior  maxillary  branch  of  the  fifth  nerve 
upon  the  act  of  deglutition  has  been  mentioned  in  a  previous 
lecture,  but  this  effect  is  due,  not  alone  to  an  absence  of  the 


TEE  PHYSIOLOGY  OF  DEGLUTITION:  4^76 

normal  muscular  power  of  the  muscles  of  mastication,  but 
also  to  an  anaesthetic  condition  of  the  mucous  lining'  of  the 
mouth,  which  renders  the  tongue  unable  to  appreciate  the 
situation  of  the  bolus  of  food  ;  as  has  been  proven  by  the  fact 
that  the  same  difficulty  exists  when  section  of  the  fifth  nerve 
is  made  in  front  of  the  ganglion  of  Gasser,  where  only  the 
sensory  portion  of  the  nerve  can  be  injured,  as  when  both  the 
motor  and  sensory  portions  of  the  nerve  are  involved,  after 
section  below  the  foramen  ovale. 

In  the  second  period  of  deglutition,  the  bolus  of  food, 
by  being  crowded  backward,  tends  to  raise  the  soft  palate ; 
and  the  levator  palati  muscle  further  assists  in  retaining  the 
palate  in  this  elevated  position,  while  the  superior  constric- 
tor muscle  of  the  pharynx  causes  the  posterior  wall  of  the 
pharynx  to  bulge  forward,  and  thus  to  meet  the  uvula.  The 
posterior  nasal  openings  are  thus  mechanically  closed  to  the 
entrance  of  the  food  into  the  chamber  of  the  nose,  prepara- 
tory to  the  series  of  reflex  movements  which  are  to  ensue,  for 
the  purpose  of  forcing  the  bolus  downward  into  the  oesopha- 
gus, and  thence  into  the  stomach. 

The  larynx  is  now  suddenly  raised^  so  as  to  bring  the 
superior  opening  of  that  organ  underneath  the  base  of  the 
tongue,  which  has  been  crowded  backward  during  the  first 
period,  in  order  to  force  the  bolus  against  the  soft  palate. 
Its  soft  structure  renders  it  admirably  adapted  to  mold  itself 
to  the  irregularities  of  outline  of  the  laryngeal  opening.  By 
this  position  of  the  tongue,  the  epiglottis  is  also  applied  over 
this  opening,'  and  the  entrance  of  food  into  the  larynx  is 
furthermore  guarded  against  by  the  approximation  of  the 
vocal  cords  by  means  of  the  adductor  muscles  of  the  larynx. 
The  muscles  which  thus  raise  the  larynx  are  the  anterior 
belly  of  the  digastric,  the  mylo-hyoid,  the  genio-hyoid,  the 
stylo-glossus,  and  some  of  the  fibers  of  the  genio-glossus. 

Simultaneously  with  the  elevation  of  the  larynx,  the  pa- 

^  It  was  formerly  supposed  that  the  epiglottis  was  the  chief  instrument  in  prevent- 
ing the  entrance  of  food  into  the  larynx,  but  the  large  number  of  cases  where  the 
epiglottis  has  been  removed,  and  no  difficulty  in  deglutition  apparently  produced,  have 
created  a  doubt  as  to  its  importance. 


476 


THE  CRANIAL  NERVES. 


lato-pharyngeal  muscles  contract  and  raise  the  lower  end  of 
the  pharynx^  thus  shortening  the  length  of  that  organ  and 
tending  to  draw  the  pharynx  over  the  bolus  of  food,  very 
much  as  a  glove  is  drawn  over  the  finger ;  while,  at  the  same 
time,  the  curve  of  the  posterior  pillars   of  the  pharynx  is 


•^ll/a*!.         EJALUt* 


Fig.  135. — Muscles  of  tlie pharynx^  etc.     (Sappey.) 

1,  2,  3,  4,  4,  superior  constrictor  ;  5,  6,  7,  8,  middle  constrictor ;  9,  10,  11,  12,  inferior  con- 
strictor; 13,  13,  stylo-pharyngeus ;  14,  stylo-hyoid  muscle;  15,  stylo-?;lossus ;  16, 
hyo-glossus;  17,  mylo-hyoid  muscle;  18,  buccinator  muscle;  19,  tensor  palati;  20, 
levator  palati. 

made  straight,  and,  by  the  approximation  of  these  muscles 
to  the  sides  of  the  uvula,  the  opening  of  the  pharynx  into 
the  nares  is  now  completely  occluded. 

The  constrictor  muscles  of  the  pharynx  now  come  into 


5; 


}J 


THE  PHYSIOLOGY  OF  DEGLUTITION.  477 

play,  contracting  in  succession  from  above  downward ;  the 
posterior  pillars  of  the  fauces,  by  their  approximation,  pre- 
vent the  bolus  from  again  entering  the  mouth  ;  and  it  is  thus 
forced  to  enter  the  oesophagus. 

It  is  apparent  that  most  of  these  movements  are  of  a  re- 
fiex  character^  and  are  excited  by  the  presence  of  the  bolus 
of  food,  which  passes  out  of  voluntary  control  as  soon  as  it 
passes  the  anterior  pillar  of  the  fauces,  at  which  point  the 
second  period  of  deglutition  may  be  said  to  commence.  Every 
reflex  act  presupposes  some  sensory  filaments  to  convey  the 
impression  to  the  brain,  and  certain  motor  filaments  to  trans- 
mit the  impulses  to  the  muscles  destined  to  act  upon  the 
bolus ;  it  is  now  believed  that  the  glosso-pharyngeal  nerve 
possesses  both  of  these  sets  of  fibers,  as  well  as  those  control- 
ling the  special  sense  of  taste.  This  nerve  may  then  be  con- 
sidered as  a  nerve  of  taste,  a  nerve  of  motion  to  the  pharyn- 
geal muscles,  and  the  true  "excitory  nerve^''  of  the  act  of 
deglutition. 

The  importance  of  the  soft  palate  in  the  act  of  deglutition 
is  particularly  shown  during  the  swallowing  of  liquids,  since 
it  has  to  be  closely  applied  to  the  base  of  the  tongue,  in  order 
to  allow  of  a  partial  vacuum  within  the  cavity  of  the  mouth, 
and  thus  to  draw  the  fluid  along  the  furrow  formed  by  the 
curving  upward  of  the  edges  of  the  tongue.  This  fact  is  clin- 
ically shown  by  patients  affected  with  paralysis  of  the  velum,' 
who  experience  great  difficulty  in  swallowing  liquids,  since 
the  fluid  is  liable  to  escape  through  the  nose.  A  case  of  this 
character  is  reported  by  Berard,  where  a  young  lady  was 
obliged  to  free  herself  from  all  observation  whenever  she  at- 
temx)ted  to  drink,  as  the  escape  by  the  nostrils  was  so  profuse 
as  to  occasion  embarrassment. 

The  prevention  of  the  entrance  of  food  into  the  cavity  of 
the  larynx,  as  has  been  mentioned,  is  insured :  first,  by  the 
base  of 'the  tongue  ;  secondly,  by  the  epiglottis ;  and,  thirdly, 

'  Paralysis  of  certain  muscles  of  the  soft  palate  occurs  when  the  facial  nerve  is  im- 
paired behind  the  point  of  origin  of  its  petrosal  branches.     For  particulars  of  this  diag- 
nostic symptom,  the  reader  is  referred  to  page  440. 
33 


478  THE   CRANIAL  NERVES. 

by  tlie  approximation  of  the  vocal  cords  ;  but  that  such  acci- 
dents do  still  happen  from  attempts  at  inspiration '  duiing 
eating  is  attested  by  the  violent  coughing  excited,  and  by 
the  instantaneous  expulsion  of  the  foreign  substance,  unless 
it  should  chance  to  become  mechanically  arrested  in  the  larynx. 
Longet  accounts  for  the  symptoms  excited  by  such  an  acci- 
dent as  the  result  of  an  exquisite  sensibility  possessed  by  the 
mucous  lining  of  the  upper  part  of  the  larynx.  It  is  well 
attested  that  the  danger  of  entrance  of  fluids  into  this  organ 
is  far  greater  than  in  the  case  of  solids ;  and  the  act  of  gar- 
gling is  especially  liable  to  be  followed  by  such  an  occurrence, 
since  the  larynx  is  much  wider  open  than  in  the  act  of  deglu- 
tition. In  the  administration  of  anaesthetics  to  patients  who 
have  eaten  largely  before  the  hour  appointed  for  surgical 
relief,  a  great  danger  of  the  entrance  of  vomited  matters 
into  the  cavity  of  the  larynx  is  encountered,  since  the  sensi-  i 
tiveness  of  the  mucous  lining  is  destroyed,  and  the  expulsive  \ 
efforts  of  Nature  are  often  wanting.' 

The  third  period  of  the  act  of  deglutition  is  confined  to 
the  oesophagus,  through  which  the  bolus  has  to  pass  to  reach  . 
the  stomach.  The  downward  movement  of  the  bolus  is  as-  ' 
sisted  by  alternate  contraction  of  the  longitudinal  fibers  of 
the  tube,  which  shorten  it  and  tend  to  draw  its  walls  upward 
over  the  bolus,  and  contraction  of  the  circular  fibers,  which 
constrict  the  tube  and  force  the  bolus  downward.  The  fact 
that  gravity  has  little,  if  anything,  to  do  with  this  downward 
movement  is  proven  by  the  fact  that  the  position  of  the  body 
does  not  seem  to  affect  it,  while  acrobats  are  often  known  to 
perform  the  feat  while  standing  upon  the  head  or  hands.  The 
time  consumed  in  the  passage  through  the  oesophagus  was 
estimated  by  Magendie '  as  about  two  minutes  in  animals,  but 

*  As  occurs  during  attacks  of  laughing,  hiccough,  etc.,  when  food  is  present  in  the 
mouth,  or  during  too  hasty  an  effort  to  consume  food. 

'  In  cases  where  this  accident  occurs,  the  tongue  should  be  forcibly  drawn  out  of  the 
mouth,  so  as  to  pull  up  the  epiglottis,  and  the  foreign  body  extracted  by  the  finger,  if 
possible,  or,  if  not,  the  patient  should  be  held  by  the  feet,  and  thus,  by  shaking  the  pa- 
tient, gravity  may  help  to  dislodge  it.  I  once  saved  the  life  of  a  man  by  this  means 
when  all  others  had  failed,  and  fatal  asphyxia  seemed  imminent. 

'  "  Journal  de  Physiol." 


I 


THE  PHYSIOLOGY  OF  DEGLUTITION.  4Y9 

it  is  probably  mucli  shorter  in  man";  although  we  are  often 
conscious  of  a  delayed  termination  of  the  act,  and  are  forced 
to  hasten  it  by  the  drinking  of  fluids,  as  most  of  us  can  attest. 
It  is  probable  that  this  peristaltic  action  of  the  oesophagus, 
like  that  of  the  intestinal  canal,  is  partly  controlled  by  the 
nervous  influence  of  the  sympathetic  system,  although  the 
pneumogastric  nerves  have  an  extensive  distribution  to  and 
a  very  marked  control  over  this  organ/ 

Deglutition  is  essentially  a  reflex  act^  save  in  its  first 
period,  when  volition  plays  an  important  part.  It  can  not 
take  place  unless  some  stimulus  is  applied  to  the  mucous 
lining  of  the  fauces  ;  and  those  apparently  voluntary  acts  of 
deglutition  which  are  produced  when  no  food  is  within  the 
mouth  are  undoubtedly  due  to  the  swallowing  of  saliva,  or 
to  irritation  of  the  fauces  by  the  base  of  the  tongue  itself. 
When  we  tickle  the  fauces,  we  can  see  all  of  the  act  of  deglu- 
tition, confined  to  the  second  period,  artificially  produced  ; 
and  this  irritability  of  the  fauces  is  so  extreme  in  some  per- 
sons as  to  render  any  attempt  to  examine  the  throat  one  of 
.difficulty,  and  often  a  cause  of  reflex  vomiting.  So  impor- 
tant is  the  education  of  the  throat  to  enable  the  patient  to 
tolerate  the  presence  of  instruments,  that  all  surgical  proced- 
ures upon  the  larynx,  if  performed  from  within  the  mouth, 
require  often  months  of  training  to  enable  the  patient  to  assist 
the  operator  in  a  step  whose  execution  may  be  a  matter  of  a 
few  seconds  only.  All  forms  of  local  applications  are  used 
to  insure  an  anaesthetic  condition  of  these  parts,  and  the  in- 
ternal administration  of  medicinal  agents  is,  furthermore, 
often  required  to  render  such  procedures  within  the  cavity 
of  the  larynx  possible. 

That  the  center  for  the  reflex  act  of  deglutition  is  confined 
to  the  medulla  oblongata  is  proven  by  experiment  on  animals 
whose  brain  has  been  entirely  removed,  with  the  exception  of 
the  medulla,  when  irritation  of  the  fauces  will  still  continue 

*  Michael  Foster  regards  this  third  act  of  deghitition  as  more  closely  dependent  upon 
the  central  nervous  system  than  the  movements  of  the  intestinal  tract,  and  attributes  it  to 
reflex  action  due  to  the  bolus. 


480  THE  CRANIAL  NERVES. 

to  produce  all  the  movements  of  the  second  stage  of  that 
act. 

CLINICAL  POINTS   OF  INTEEEST   PERTAINING  TO  THE  GLOSSO-PHARYN- 

GEAL  NERVE. 

The  intimate  association  which  apparently  exists  between 
the  libers  of  this  nerve  and  the  sense  of  taste,  the  movements 
of  the  pharyngeal  muscles,  and  the  reflex  acts  excited  by  the 
presence  of  a  bolus  or  of  some  foreign  source  of  irritation  to 
the  isthmus  of  the  fauces  and  the  walls  of  the  pharynx,  would 
seem  to  suggest  that  any  impairment  of  the  glosso-pharyngeal 
would  be  followed  by  clinical  evidences  of  imperfect  perform- 
ance of  each  and  all  of  these  functions.  It  is,  however,  to  be 
regretted  that  the  questions  of  the  course,  origin,  and  func- 
tions of  the  chorda  tympani  nerve,  the  exact  distribution  of 
the  fibers  of  the  glosso-pharyngeal  nerve  to  the  tongue,  and 
the  source  from  which  this  latter  nerve  derives  its  motor  fila- 
ments, are,  as  yet,  disputed  points  among  physiologists  ;  and 
the  sources  of  doubt  are  not  removed,  but  rather  increased,  by 
the  results  of  pathological  observation,  since  they  often  seem 
contradictory,  and  thus  prove  rather  a  source  of  embarass- 
ment  than  an  aid  to  definite  conclusions. 

One  would  naturally  suppose,  provided  that  he  was  fa- 
miliar with  the  symptoms  of  that  disease,  called  by  Duchenne 
*'glosso-labio-laryngeal  paralysis"  (although  the  word  "pha- 
ryngeal" is  often  used  in  place  of  "laryngeal"  to  express  the 
same  condition),  that  the  difficulty  experienced  in  deglutition 
would  certainly  indicate  that  the  nerve  which  apparently  pre- 
sides over  that  function  would  be  found  in  a  state  of  disease  ; 
but,  on  the  contrary,  the  glosso-pharyngeal  nerve  is  not  re- 
ported, to  my  knowledge,  as  having  anything  to  do  with  that 
affection.  We  must,  therefore,  be  forced  to  infer  that  the 
motor  filaments  of  the  pharynx  are,  to  a  great  extent,  con- 
trolled by  other  nerves  ;  and  that,  if  they  are  apparently 
branches  of  the  ninth  cranial  nerve,  they  are  to  be  accounted 
for  as  fibers  derived  from  communicating  filaments  from  other 
sources. 


J 


CLINICAL    CONDITIONS   CAUSING  HYPERGEUSIA.      481 

Hirschfeld  claims  to  have  verified  a  branch  of  the  glosso- 
pharyngeal nerve  which  extends  to  the  anterior  two  thirds  of 
the  tongue ;  hence  the  strong  probability  that  it  partially 
controls  the  sense  of  taste  in  that  portion  as  well  as  in  the 
posterior  third  of  the  organ.  Stannius,  by  experiments, 
thinks  that  he  has  established  the  function  of  this  branch, 
and  he  attributes  to  it  the  power  of  perception  of  Mtter 
substances  only,  the  other  varieties  of  taste  sensations 
being  presided  over  by  the  chorda  tympani  nerve  or  the 
gustatory  branch  of  the  fifth  nerve.  We  know,  clinically, 
that  the  conditions  of  hyperaesthesia  and  anaesthesia  of 
the  gustatory  nerves  are  verified  by  many  interesting  phe- 
nomena ;  and  we  must  be  content  to  wait  for  the  solution 
of  the  other  mixed  problems  of  gustation,  until  they  are 
solved  by  further  clinical,  physiological,  and  pathological 
observation. 

The  condition  of  gustatory  JiypercBstJiesiaj  called  also 
''Jiypergeusia^^'^ '  is  very  marked  in  certain  patients  who  are 
in  an  anaemic  and  nervous  condition,  while  it  is  a  frequent 
phenomenon  in  hysteria  and  in  melancholia.  In  such  cases 
an  apparent  gustatory  sensation  may  be  often  excited  by  the 
application  of  an  electric  current  to  the  cervical  or  upper 
dorsal  region  of  the  spine. 

True  gustatory  hypersesthesia  may  express  itself  as  an  in- 
crease in  the  delicacy  of  the  gustatory  sensation,  so  that  ex^- 
tremely  small  quantities  of  sapid  substances  maybe  perceived. 
We  thus  occasionally  meet  with  hysterical  patients,  who  can 
perceive  the  taste  of  certain  medicinal  agents  in  a  solution 
which  to  the  healthy  subject  would  be  tasteless.  It  may  exr 
press  itself,  again,  as  an  unnatural  enjoyment  of  food,  or  a 
loathing  of  certain  dishes  which  convey  a  sense  of  taste  which 
does  not  in  reality  exist.  In  facial  paralysis  of  rheumatic 
origin,  abnormal  gustatory  sensations  are  sometimes  present, 
as  sweetish,  sour,  or  sapid  tastes,  within  the  mouth.  In  the 
insane,  hallucinations  of  the  special  sense  of  taste,  usually  of 

^  See  experiments  of  Valentin  and  Keppler,  made  to  determine  the  exact  degree  of 
gustatory  sensibility  and  excitability. 


482  THE  CRANIAL  NERVES. 

2b  disagreeable  character,  are  often  present,  and  indicate  some 
disease  of  central  origin. 

The  condition  of  gustatory  ancesthesia^  called  '^  ageusia,'^ "^ 
comprises  all  those  phenomena  which  indicate  either  a  partial 
or  complete  loss  of  the  sense  of  taste.  Thus,  the  tongue  may 
be  able  to  appreciate  certain  substances,  and  be  insensible  to 
others,  while  the  anaesthetic  condition  may  be  circumscribed 
or  diffused,  as  regards  its  anatomical  distribution,  affecting 
either  the  tip  of  the  tongue,  its  root,  or  one  or  both  sides. 
This  abnormal  state  is  observed  after  paralysis  of  the  trige- 
minus, severe  injuries  to  the  trigeminus  or  the  glosso-pharyn- 
geal  nerves,  intra-cerebral  growths  which  create  compression 
of  the  glosso-pharyngeal  or  trigeminus, '  and  atrophy  of  the 
nerves,  as  the  result  of  compression,  and  of  disease  of  their  in- 
herent fibers.  As  a  rule,  when  this  condition  exists,  we  shall 
find  a  similar  condition  of  the  optic,  olfactory,  trigeminus, 
pneumogastric,  spinal  accessory,  or  some  of  the  cutaneous 
branches  to  the  face. 


THE  PNEUMOGASTRIC,  OR  TENTH  NERVE. 

Owing  to  the  numerous  connections  of  the  pneumogastric 
with  other  nerves,  its  varied  and  extensive  distribution,  and 
the  important  character  of  its  functions,  this  may  properly  be 
regarded  as  one  of  the  most  remarkable  nerves  of  the  whole 
body.  It  has  been  often  known  by  the  name  of  the  ^'par  va- 
gum^^^  from  the  wandering  course  of  its  fibers,  which  are 
distributed  to  five  different  vital  organs,  viz.  :  the  heart, 
lungs,  stomach,  liver,  and  intestines,  as  well  as  to  many  other 
parts  of  secondary  importance. 

This  nerve,  like  the  seventh,  eighth,  and  ninth  nerves,  is 
considered  by  comparative  anatomists  as  belonging  to  the 

'  In  the  case  reported  by  Bottclier,  although  ageusia  existed,  the  patient  complained 
of  a  constant  burning  and  bitterness  within  the  mouth.  An  autopsy  showed  the  presence 
of  a  tumor  of  the  base  of  the  brain,  which  had  caused  atrophy  of  the  glosso-pharyngeal 
and  pneumogastric  nerves  by  a  steady  compression.  Longet  reports  cases  where  the 
nerves  passing  through  the  jugular  foramen  were  all  more  or  less  destroyed  by  pressure 
from  a  similar  cause. 


J 


THE  PKEUMOGASTRIC,  OR   TENTH  NERVE. 


483 


class  of  spinal  nerves,  since  it  arises  directly  and  entirely  from 
the  upper  portion  of  tlie  spinal  cord.  Its  superficial  point  of 
origin  lies  in  the  groove  between  the  olivary  and  restiform 
bodies  of  the  medulla,  while  its  deep  point  of  prigin  may  be 
traced  to  a  gray  nucleus  in  the  floor  of  the  fourth  ventricle, 
slightly  below  the  nucleus  for  the  glosso-pharyngeal  nerve.' 

There  is  a  very  close  afiiliation  between  the  deep  fibers  of 
the  pneumogastric  and  glosso-pharyngeal  nerves  within  the 


Fig.  136. — AnaMomoaes  of  the  pneumogastric  nei've.     (Ilirschfeld.) 

1,  facial  nerve;  2,  glosso-pharyngeal  nerve;  2',  anastomoses  of  the  glosso-pharyngeal 
with  the  facial ;  3,  3,  pneumogastric,  toith  its  two  ganglia  ;  4,  4,  spinal  accessory  ; 
5,  sublingual  nerve  ;  6,  superior  cervical  ganglion  of  the  sympathetic ;  7,  anastomotic 
arcade  of  the  first  two  cervical  nerves  ;  8,  carotid  branch  of  the  superior  cervical 
ganglion  of  the  sympathetic;  9,  nerve  of  Jacobson ;  10,  branches  of  this  nerve  to 
the  sympathetic;  11,  branch  to  the  Eustachian  tube;  12,  branch  to  the  fenestra 
ovalis  ;  13,  branch  to  the  fenestra  rotunda;  14,  external  deep  petrous  nerve;  15, 
internal  deep  petrous  nerve  ;  16,  otic  ganglion  ;  17,  auricular  branch  of  the  pneumo- 
gastric ;  \9>^  anastomosis  of  the  pneumogastric  with  the  spinal  accessory;  19,  anasto- 
mosis of  the  pneumogastric  with  the  sublingual ;  20,  anastomosis  of  the  spinal  acces- 
sory with  the  second  pair  of  cervical  nerves;  21,  pharyngeal  plexus;  22,  superior 
laryngeal  nerve. 


substance  of  the  medulla  oblongata,  so  close  indeed  as  to  lead 
some  authors  to  consider  them  identical  with  each  other. 
These  deep  fibers  may  be  traced,  in  part,  into  the  substance 
of  the  restiform  body,  a  small  bundle  toward  the  cerebellum, 

'  See  previous  page  of  this  section,  in  which  the  deep  origin  of  the  nerve  is  discussed. 


484 


THE  CRANIAL  NERVES. 


Fig.  137. — A  dicu/ram  showing  the   branches  of  distribution   and  communication  of  the 
pneumogastric  nerve.     Cervical  portion  of  nerve. 

1,  the  filaments  of  origin  of  the  pneumogastric  nerve;  2,  the  spinal  accessory  new  e  escap- 
ing from  the  medulla  oblongata,  below  the  pneumogastric  nerve ;  3,  the  upper  com- 
municating filament  between  the  pneumogash'ic  and  the  spinal  accessory  nerves  (often 
absent);  4,  the  '■^  ganglion  of  the  root,''''  situated  in  the  jugular  foramen  ;  5,  the  jugu- 
lar forameyi,  showing  the  transmission  of  three  nerves  ;  6,  the  communicating  filament 
between  the  pneumogastric  and  the  glosso-pharyngeal  nerves ;  Y,  the  glosso-pharyngeal 
nerve,  from  its  point  of  origin  to  its  escape  from  the  cavity  of  the  cranium ;  8,  the 
^ganglion  of  the   trunk""  of  the  pneumogastric  nerve;   9,  the  loioe^-  filamerU   of 


i 


GANGLIA   OF  THE  PNEUM0GA8TRIG  NERVE.  485 

communication  between  the  piieumogastric  and  spinal  accessory  nerves,  which  probably 
controls  the  muscles  of  the  larynx  concerned  in  phonation  and  respiration ;  10,  t^he 
communicatitiff  Jilament  from  the  arcade,  formed  by  the  first  and  second  cervical 
nerves  ;  11,  the  communicating  filament  from  the  facial  nerve,  which  helps  to  form 
the  auricular  branch  of  the  pneumogastiic  or  "Arnold's  nerve  "  ;  12,  the  three  sets  of 
filaments  which  join  the  pneumogastric  nerve  to  the  superior  cervical  ganglion  of  the 
sympathetic  system;  13,  the  auricular  branch  of  the  pneumogastric,  ov '"'■  Arnold's 
nerve^''  partly  formed  by  the  facial  filament  (11);  14,  the  branches  to  the  ^'•pharyn- 
geal plexus,''''  formed  also  in  part  by  the  glosso-pharyngeal ;  15,  the  superior  laryngeal 
nerve,  supplying  the  mucous  lining  of  the  larynx  and  the  crico-thyroid  muscle ;  16, 
the  "  depiressor  nerve  of  the  heart,''''  formed  by  two  roots,  one  from  the  pneumogastric, 
and  the  other  from  the  superior  laryngeal  nerve  ;^  IV,  the  inferior  or  recurrent 
laryngeal  nerve,  winding  around  an  artery  (19),  and  then  returning  to  the  larynx  to 
supply  the  muscles  of  phonation  ;2  18,  the  cervical  cardiac  nerves  (sometimes  three 
in  number),  going  to  the  cardiac  plexus  ;  19,  the  subclavian  artery  (if  on  the  right 
side),  and  the  arch  of  the  aorta  (if  on  the  left  side  of  the  body). 

and  a  few  toward  the  cerebrum  ;  but  the  larger  portion  pass 
to  the  median  line  of  the  floor  of  the  fourth  ventricle  or  de- 
scend into  the  substance  of  the  medulla  oblongata. 

The  pneumogastric  nerve  emerges  from  the  jugular  fora- 
men as  a  single  trunk,  but  immediately  develops  two  gan- 
glia, the  upper  of  which  is  called  the  ^'jugular  ganglion^'' ^ 
or  the  ''  ganglion  of  the  root,^^  since  it  lies  close  to  and  some- 
times within  the  foramen  of  that  name.  After  the  nerve 
emerges  from  the  foramen,  another  ganglion,  about  one  quar- 
ter of  an  inch  in  length,  is  developed,  called  the  ^'ganglion 
of  the  trunks  Within  the  jugular  ganglion,  an  interchange 
of  fibers  takes  place  between  the  pneumogastric  and  spinal 
accessory  nerves  ;  and  it  seems  clear  that  the  laryngeal  and 
pharyngeal  branches  (which  are  among  the  most  decidedly 
motor  of  those  given  off  from  the  pneumogastric)  may  all,  in 
great  part,  be  traced  backward  into  the  spinal  accessory 
nerve. 

The  researches  of  Valentin,  Morganti,  Longet,  and  others 
seem  to  prove  that  the  pneumogastric  nerve  at  its  root  pos- 
sesses no  motor  power,  but  is  entirely  an  afferent  nerve,  al- 
though Stilling,  Wagner,  Muller,  Yolkman,  and  Bernard  fail 

^  For  the  physiological  effect  of  stimulation  of  this  nerve,  see  the  late  researches  of 
Cyon  and  Ludwigupon  this  nerve  in  the  rabbit;  also  text-books  of  physiology  of  Michael 
Foster,  A.  Flint,  Jr.,  and  others.  In  man,  this  nerve  is  probably  associated  with  one  of 
the  cardiac  nerves. 

2  The  filament  of  the  spinal  accessory  (No.  9  in  the  cut)  is  supposed  to  afford  to 
this  nerve  its  motor  power,  having  simply  used  the  sheath  of  the  pneumogastric  as  a 
means  of  protection  in  its  course  down  the  neck.  The  physiological  import  of  this  nerve 
shows  the  vital  necessity  for  such  protection. 


486  TBE  CRANIAL  NERVES. 

to  attribute  all  the  motor  fibers  of  this  nerve  to  either  the 
spinal  accessory  or  glosso-pharyngeal  nerves,  and  maintain 
that  motor  fibers  may  be  demonstrated  within  the  root  of  the 
pneumogastric  above  the  jugular  ganglion. 

In  regard  to  its  trunk^  there  can  be  no  doubt  that  the 
pneumogastric  is  to  be  considered  as  a  nerve  of  double  en- 
dowments, although  it  is  certain  that  these  endowments  are 
very  differently  distributed  among  its  branches.  That  it  is 
capable  of  conveying  those  impressions  which  become  sensa- 
tions when  communicated  to  the  sensorium  is  experimentally 
proved  by  the  fact  that,  when  its  trunk  is  pinched,  the  ani- 
mal gives  signs  of  acute  pain  ;  and  it  is  also  evident  from  the 
painful  consciousness  we  occasionally  have  of  any  abnormal 
condition  of  the  organs  which  it  supplies. 

BRANCHES  OF  THE  PNEUMOGASTRIC  NERVE. 

The  pneumogastric  nerve,  by  means  of  its  numerous  points  | 
of  distribution,  participates  in  the  operations  of  deglutition^  '\ 
pTionation^  respiration^  the  circulation  of  the  blood,  and  : 
the  process  of  digestion.  To  fully  describe  the  variations  in  ij 
its  course  from  above  downward,  and  the  distribution  of  its  \ 
branches  to  the  various  organs  (in  all  of  their  physiological  \ 
bearings),  you  must,  of  necessity,  be  carried  into  a  discus-  I 
sion  of  the  thoracic  and  abdominal  viscera  and  the  physio-  { 
logical  acts  which  they  perform.  A  hasty  enumeration  of  the  | 
general  course  of  the  fibers  of  this  nerve  can,  therefore,  only  { 
be  given  here,  reserving  the  many  points  of  interest  connected  ; 
with  it  for  other  lectures,  when  the  viscera  will  be  considered.  ; 

The  efferent  fibers  of  the  pneumogastric  nerve  include  cer- 
tain motor  branches  which  are  distributed  into  the  pharynx,  j 
the  larynx,  the  oesophagus,  the  stomach,  and  the  intestinal  ' 
canal.  ■ 

The  pharyngeal  branches  help  to  form  the  pharyngeal  ;; 
plexus  of  nerves,  and  thus  to  aid  in  the  movements  of  the  | 
muscles  of  that  organ  during  the  second  period  of  deglutition.'  \ 

'  See  lecture  upon  the  glosso-pharyngeal  nerve,  where  the  act  of  deglutition  is  fully  ' 
discussed. 


DISTRIBUTION  OF  PNEUM00A8TRIG  NERVE.  487 

It  is  also  probable  that  these  same  muscles  tend  to  modify 
the  tone  and  quality  of  the  T)oice^  and  also  to  assist  in  the 


Fig.  138. — Thoracic  and  abdominal  portion  of  the  nerve. 

20,  the  thoracic  cardiac  nerves,  assisting  to  form  the  cardiac  plexus  ;  21,  the  filaments  of 
coramunication  between  the  pneumogastric  nerve  and  the  thoracic  ganglia  of  the  sym- 
pathetic system ;  22,  the  branches  given  off  by  the  pneumogastric  nerve  to  assist  in 
forming  the  posterior  pulmonary  plexus  ;  23,  the  branches  given  off  to  assist  in  form- 
ing the  anterior  pulmonary  plexus ;  24,  the  branches  which  form  the  cesopliageal 
plexus,  and  assist  in  the  performance  of  the  third  period  of  the  act  of  deglutition ; 
25,  the  gastric  branches,  supplying  the  coats  of  the  stomach  ;  26,  the  hepatic  branches, 
accompanying  the  portal  system  of  veins  ;  27,  the  intestinal  branches,  controlling,  to 
a  large  extent,  the  peristaltic  action  of  that  canal ;  28,  branches  which  can  be  traced 
to  the  kidneys,  the  spleen,  and  the  supra-renal  capsides. 


488 


THE  CRANIAL  NERVES, 


articulation  of  sounds  or  words,  although  the  lingual  muscles 
and  those  of  the  lips  are  more  directly  concerned  in  the  latter 
function. 


Fig.  139. — Distribution  of  the  pneumogastric.     (Hirschfeld.) 

1,  ti'unk  of  the  left  pneumogastric  ;  2,  ganglion  of  the  trunk  ;  3,  anastomosis  rcith  the  spinal  \ 
accessori/  ;  4,  anastomosis  loith  the  sublingual ;  5,  pharyngeal  branch  (the  auricular  * 
branch  is  not  shown  in  the  figure)  /  6,  superior  laryngeal  branch  ;  7,  external  laryngeal  [ 
nej've ;  8,  laryngeal  plexus ;  9,  9,  inferior  laryngeal  branch;  10,  cervical  cardiac^ 
branch;  11,  thoracic  cardiac  branch;  12,  13,  pulmonary  branches;  14,  lingnali 
branch  of  the  fifth  ;  15,  lower  portion  of  the  sublingual;  1 6,  glosso-pharyngcal ;  17,; 
spinal  accessory ;  18, 19,  20,  spinal  nerves  ;  21,  phrenic  nerves ;  22,  23,  spinal  nerves ;  \ 
24,  25,  26,  27,  28,  29,  30,  sympathetic  ganglia.  j 

The  laryngeal  branches  are  two  in  number,  and  are  called  i 
the  superior  and  inferior;  although  the  name  ''recurrent  la- ^ 
ryngeal  nerve"  is  more  often  applied  to  the  latter  on  account  j 


li 


PHYSIOLOGY  OF  PNEUM0GA8TRIG  NERVE.  489 

of  the  peculiarity  of  its  course,  since  it  winds  around  the  sub- 
clavian artery  before  returning  to  the  larynx,  upon  the  right 
side  of  the  body,  while  the  left  nerve  winds  around  the  arch 
of  the  aorta,  and  then  turns  backward,  to  be  distributed 
to  the  muscles  of  the  larynx.  It  is  by  means  of  these  laryn- 
geal nerves  that  the  muscles  which  move  the  vocal  cords, 
and  thus  control  the  voice,  are  supplied  ;  while  the  same  mus- 
cles are  important  agents  in  so  adapting  the  size  of  the  open- 
ing between  the  vocal  cords,  during  inspiration,  as  to  allow 
of  an  unimpeded  entrance  of  air  to  the  lungs. '  As  the  infe- 
rior nerve  is  the  one  which  supplies  all  of  the  laryngeal  mus- 
cles but  the  crico-thyroid  and  a  portion  of  the  arytenoid,  it 
becomes  to  the  physiologist  a  nerve  of  great  importance,  since 
the  acts  of  respiration  and  phonation  are  directly  under  its 
influence.  Experiment  seems  to  have  proven,  however,  that 
the  laryngeal  nerves,  although  apparently  deriving  their  mo- 
tor power  from  the  pneumogastric,  are,  in  reality,  but  fibers 
of  the  spinal  accessory  nerve,  which  have  used  the  sheath  of 
the  pneumogastric  nerve  simply  for  protection  in  their  pas- 
sage through  the  neck.  The  spinal  accessory  nerve  is,  there- 
fore, sometimes  called  the  "  superior  respiratory  nerve  of 
Bell,"  since  it  controls  the  movements  of  the  laryngeal  mus- 
cles during  the  act  of  inspiration  ; "  which  are  the  highest,  in 
point  of  situation,  of  any  of  the  respiratory  muscles. 

The  branches  to  the  cesophagus,  stomach,  and  intestine 
are  the  principal  agents  in  promoting  the  peristaltic  action  of 
the  alimentary  canal,  and  they  thus  aid  in  the  acts  of  degluti- 
tion and  digestion.  It  is  probable,  also,  that  the  pneumo- 
gastric nerves  are  capable  of  directly  affecting  the  secretions 
of  the  alimentary  canal,  although  the  sympathetic  system  is 

'  The  researches  of  Bernard  have  done  much  to  call  professional  attention  to  the  fact 
that  the  pneumogastric  and  spinal  nerves  are  alone  involved  in  ordinary  respiration,  but 
that,  when  it  becomes  necessary  to  bring  the  respiratory  movements  into  perfect  accord 
with  the  requirements  of  animal  life  (as  in  adapting  the  action  of  the  muscles  of  the 
larynx  to  production  of  voice),  the  spinal  accessory  nerve  becomes  an  indispensable  aid. 

2  This  statement  is  one  that  will  admit  of  question.  The  reader  is  referred  to  the 
experiments  of  Bernard  and  Bischoff  (as  given  on  a  subsequent  page)  for  the  difference 
between  the  effect  of  the  spinal  accessory  fibers  upon  the  glottis  from  those  of  the  pneu- 
mogastric itself. 


490 


THE  CRANIAL  NERVES. 


still  regarded  as  the  means  by  wMch  these  nerves  exert  their 
influence  upon  that  portion  of  the  body. 


Fig.  140. — Nei'ves  of  the  larynx,  posterior  Fig.  141. — Nerves  of  the  larynx^  lateral 

view.     (After  Sappey.)  view.     (After  Hirschfeld.) 

Fig.  140.— 1, 1,  superior  laryngeal  nerves  passing  through  the  thyro-hyoid  membrane ;  2,  2, 
external  laryngeal  branch  supplying  the  erieo-thyroid  muscle ;  3,  ascending  branches 
distributed  to  the  mucous  membrane  of  the  tongue  ;  4,  transverse  branches  distribu- 
ted to  the  mucous  membrane  of  the  epiglottis  and  the  aryteno-epiglottidean  folds  ;  5, 
descending  branches  passing  to  the  mucous  membrane  covering  the  posterior  surface 
of  the  larynx  (two  of  these,  of  considerable  size,  cross  the  arytenoid  muscle  to  supply 
the  mucous  membrane  lining  the  walls  of  the  vestibule) ;  6,  branch  connecting  the 
superior  with  the  inferior  laryngeal  nerve ;  7,  the  same  branch  divided  near  its  point 
of  origin ;  8,  8,  inferior  laryngeal  nerve ;  9,  branch  to  the  posterior  crico-arytenoid 
muscle,  which  is  here  divided  in  order  to  show  the  next  nerve ;  1">,  branch  to  the 
arytenoid  winding  under  the  lower  border  of  the  muscle  so  as  to  enter  it  from  its 
inner  surface;  11,  branch  to  the  lateral  crico-arytenoid  muscle;  12,  branch  to  the 
thyro-arytenoid  muscle. 

Fig.  141. —a,  section  of  the  hyoid  bone;  ft, section  of  the  thyroid  cartilage;  c,  thyro-hyoid 
membrane ;  </,  cricoid  cartilage ;  c,  trachea  ;  /,  oesophagus ;  g,  epiglottis  ;  A,  superior 
cornu  of  the  thyroid  cartilage  ;  i,  great  cornu  of  the  hyoid  bone ;  k,  lateral  thyro-hyoid 
ligament ;  Z,  thyro-hyoid  membrane ;  m,  posterior  crico-arytenoid  muscle  ;  n,  lateral 
crico-arytenoid  muscle ;  o,  thyro-arytenoid  muscle ;  jd,  base  of  the  tongue ;  1,  recur- 
rent laryngeal  nerve ;  2,  branches  given  off  from  this  nerve  to  the  posterior  crico- 
arytenoid muscle ;  3,  branch  to  the  lateral  crico-arytenoid  muscle ;  4,  branch  to  the 
thyroarytenoid  muscle ;  5,  branch  to  the  arytenoid  muscle ;  6,  right  superior  laryn- 
geal nerve ;  7,  anastomosis  of  this  nerve  with  the  inferior  laryngeal ;  8,  descending 
branches  from  the  superior  laryngeal ;  9,  middle  branches  of  the  same  nerve ;  10, 
ascending  branches. 

In  addition  to  the  branches,  which  are  considered  as  of  the 
greatest  physiological  importance,  certain  other  motor  fibers 


PHYSIOLOGY  OF  PNEUM0QA8TRIG  NERVE, 


491 


ire  now  traced  with  tolerable  certainty  to  the  trunk  of  the 
Dneumogastric  nerve,  which  are  not  unimportant.  Thus  we 
oaay  include  certain  nerves  which  supply  the  plain  muscular 
fibers  of  the  trachea  and  of  the  larger  bronchial  tubes,  fibers 
which  exert  a  vaso -motor ial  influence  upon  the  blood-vessels 
of  the  lungs,  an  inMMtory  nerve  for  the  heart,  and  certain 
fibers  which  are  distributed  to 
Tthe  lungs  and  the  heart,  which 
are  supposed  to  exert  a  trophic 
influence. 

The  properties  and  functions 
of  the  cardiac  nerve,  and  in 
what  way  the  pneumogastric 
nerve  influences  the  action  of 
the  heart,  are  physiological 
questions  of  the  greatest  impor- 
tance. It  is  now  known  that 
section  of  the  pneumogastric  in 
the  neck,  instead  of  arresting 
the  action  of  the  heart,  in- 
creases the  frequency  of  its 
contractions ;  while  galvanism 
of  the  divided  ends  causes  the 
heart's  action  to  stop  during  its 
diastole,  if  the  current  be  a 
powerful  one,  and,  if  a  weak 
one,  the  heart's  action  is  propor- 
tionately slowed. 

The  depressor  nerve  of  the 
heart  is  shown,'  in  the  diagram- 
matic representation  of  the  pneu- 
mogastric nerve  and  its  branches,  to  arise  from  two  filaments, 
derived,  respectively,  from  the  pneumogastric  and  the  superior 
laryngeal  nerves.     The  importance  of  this  nerve  in  explaining 

'  For  the  method  of  origin  of  this  nerve,  see  the  diagrammatic  plate  of  the  upper 
half  of  the  pneumogastric  nerve,  page  484.  While  the  diagram  illustrates  the  construc- 
tion of  this  nerve,  as  found  in  the  rabbit  by  Cyon,  it  is  still  questionable  whether  a  simi- 
lar method  of  origin  can  be  demonstrated  in  man.  That  the  nerve  exists  is  not  a  matter 
of  doubt ;  but  it  is  impossible  to  positively  state  its  method  of  origin  or  its  precise  coursa 


Fig.  142. — Branches  of  the  pneumogastric 

to  the  heart.     (Bernard.) 
C,  heart ;  a,  carotid  artery  going  to  the 
brain ;  n,  branches  of  the  pneumo- 
gastric going  to  the  heart. 


492  T^SE  CRANIAL  NERVES. 

many  physiological  effects  of  galvanism  of  the  pneumogastric 
has  been  developed  through  the  efforts  of  Cyon  and  Ludwig, 
in  their  prize  essay  of  1867,  who  showed  to  the  profession  its 
power  of  decreasing  the  blood-pressure,  and  who  thus  afforded 
the  means  of  satisfactorily  explaining  many  phenomena  met 
with  in  the  daily  practice  of  medicine.     If  the  abdomen  of  a 
frog  be  exposed,  and  the  intestine  struck  sharply,  the  heart  i 
will  be  seen  to  stand  still,  as  if  the  pneumogastric  trunk  had  | 
been  strongly  galvanized ;   while  stimulation  of  the  mesen- 
teric nerves,  before  they  join  the  sympathetic  chain,  wiU 
have  a  like  result.     It  has  been  found  that  the  irritation  of 
an  inflamed  peritoneal  surface,  even  if  gently  practiced,  will 
decrease  the  heart  pulsations,  and  that  severe  shock  or  very  I 
intense  pain,  no  matter  where  it  arises,  will  also  have  the  \ 
same  effect  upon  the  heart.  | 

Such  evidences  of  reflex  action  are  apparently  transmit-  j 
ted  through  the  cardio-inhibitory  nerve  fibers,  and  they  help  i 
us  to  explain  why  pain  may  create,  in  the  human  race,  at- 
tacks of  fainting,  and  why  some  types  of  inflammatory  dis-  i 
eases  and  states  of  collapse  and  shock  are  associated  with  a  i 
decrease  in  the  pulsations  of  the  heart.    The  action  of  atropin, 
even  in  small  doses,  seems  to  entirely  arrest  the  influence  of 
this  nerve  upon  the  heart,  and  a  guide  to  the  administration 
of  this  drug  may  thus  be  derived  from  physiology,  while 
the  effects  thereof  may,  in  some  instances,  be  thus  made  i 
clear.  \ 

The  cardiac  nerves  of  the  pneumogastric  are  undoubtedly  "j 
connected  with  the  other  nerves  of  the  cardiac  ganglia,''  and  \ 
act  upon  the  heart  fibers  indirectly,  rather  than  directly,  with-  i 
out  the  intervention  of  the  ganglion.  It  has  lately  been  proven  « 
that  certain  other  cardiac  nerves,  whose  function  is  accelera-  \ 
tory,  rather  than  depressing,  to  the  heart,  can  be  traced  to  the  ; 
cervical  portion  of  the  spinal  cord  as  their  point  of  origin,  \ 
but  they  have  no  connection  with  the  pneumogastric  nerve.      J 

'  The  vasomotor  nerves  of  the  lung  are  derived,  according  to  Franck,  from  the  upper  | 
cervical  ganglia  of  the  sympathetic,  their  primary  origin,  however,  being  in  the  ccrvico-  ' 
dorsal  region  of  the  cord.  j 


PHYSTOLOGY  OF  PNEUM0GA8TRIG  NERVE,  493 

The  afferent  fibers  of  the  pneumogastric  nerve,  or  those 
which  carry  impressions  from  the  periphery  of  the  nerve  to- 
ward its  point  of  origin,  comprise  the  sensory  filaments '  dis- 
tributed to  the  entire  respiratory  tract,  and  also  those  sensory 
nerves  which  supply  the  pharynx,  the  oesophagus,  and  the 
stomach  ;  fibers  which  assist  to  produce  the  secretion  of  the 
saliva ;  fibers  which  tend  to  arrest  the  secretion  of  the  pan- 
creas ;  a  special  inhibitory  nerve  upon  the  xaso-motor  center 
of  the  medulla  oblongata  ;  and,  finally,  a  special  set  of  fibers 
which  both  augment  and  retard,  at  will,  the  action  of  the 
respiratory  center  of  the  medulla  oblongata. 

As  the  pneumogastric  nerve  is  more  apparently,  although 
perhaps  not  more  importantly,  connected  with  the  act  of  respi- 
ration, we  will  first  consider  the  two  sets  of  fibers  which  have 
been  mentioned  above  as  influencing  the  action  of  the  respira- 
tory center.  It  has  been  shown  by  Rosenthal  that  the  supe- 
rior laryngeal  nerve,  when  stimulated  by  a  galvanic  current, 
decreases  the  number  of  respirations,  while  the  main  trunk 
of  the  pneumogastric  nerve,  when  similarly  stimulated,  tends 
to  increase  the  number  of  respirations.  Thus,  the  fact  that 
the  vagus  nerve  possessed  two  sets  of  respiratory  fibers,  an 
acceleratory  and  an  inhibitory,  seems  to  be  well  established, 
although  some  observers  have  not,  as  yet,  admitted  the  posi- 
tiveness  of  the  experiment. 

As  regards  those  branches  of  the  pneumogastric  which 
seem  to  exert  a  specific  influence  upon  the  various  secretions 
of  the  alimentary  canal,  we  have  yet  much  to  learn.  As  a 
general  rule,  it  may  be  stated  that  anything  which  tends  to 
create  an  increased  activity  in  the  epithelial  cells,  rather  than 
in  the  blood  supply  of  the  part,  tends  also  to  increase  the  se- 
cretion.    Thus  a  drug  may  excite  any  special  secretion,  first, 

^  Sommerbrodt  ("  Centralbl.  f.  d.  mcd.  Wiss.,"  December,  1880)  points  out  a  mechan- 
ism of  compensation  by  which  the  action  of  the  lungs  and  of  the  heart  is  coordinated. 
Thus,  a  rise  in  the  intra-bronchial  pressure  (as  occurs  in  singing,  crying,  coughing,  etc.), 
by  irritating  the  sensory  nerves  of  the  hmgs,  excites  a  reflex  depressing  action  on  tlie 
vaso-motor  and  cardio-inhibitory  nerves.  The  resulting  vascular  dilatation  and  accelera- 
tion of  the  heart's  action  react  upon  the  lung  in  two  ways.  They  prevent  the  natural  ten- 
dency to  stasis  of  the  blood  in  the  bronchial  walls,  and  they  insure  the  rapid  renewal  of 
oxygen,  demanded  by  the  increase  in  pulmonary  activity. 
34 


494  THE  CRANIAL  NERVES. 

by  acting  upon  the  nerve  center  which  controls  that  part; 
secondly,  by  a  reflex  act  through  the  nerves  of  the  part; 
thirdly,  by  acting  as  a  direct  chemical  stimulus  to  the  cells  ; 
and,  fourthly,  by  increasing  the  amount  of  blood  in  the 
part,  through  dilatation  of  the  blood-vessels. 

That  an  inhibitory  effect  upon  the  vaso-motor  center  of  th 
medulla  is  possessed  by  some  of  the  fibers  of  the  pneumogas- 
tric  nerve,  is  proven  by  the  effect  of  galvanism  of  the  vagus 
upon  blood  pressure  ;  since,  when  the  depressor  nerve  of  the 
heart  is  divided  and  the  end  connected  with  the  brain  is  gal- 
vanized, the  blood  pressure  falls,  although  the  heart  is  not 
affected,  as  it  would  be  if  the  cardiac  portion  of  the  nerve 
were  stimulated. 


I 


COURSE   OF  THE   PNEUMOGASTRIC   NERVE   OF   THE   TWO   SIDES.         ^ 

The  important  functions  of  the  vagus  render  it  necessarjWk 
that  every  precaution  shall  be  taken  by  Nature  to  prevent  its  1^' 
possible  injury,  especially  during  its  passage  through  the  \ 
neck  ;  since,  within  the  thorax  and  the  cavity  of  the  abdomen,  \ 
the  viscera  and  the  bony  encasements  tend  to  render  all  possi-  : 
ble  dangers  of  injury  a  minimum.  We  therefore  find  this  \ 
nerve  inclosed  within  the  sheath  of  the  carotid  artery,  where  ; 
it  is  placed  between  the  artery  and  the  internal  jugular  vein,  j 
lying  also  posteriorly  to  them  both.  By  this  provision  the  j 
nerve  is  placed  between  fiuid  upon  either  side,  and  thus  all  \ 
danger  of  transmitted  force  affecting  it  is  obviated,  while  the  '- 
deep  situation  of  the  carotid  and  the  close  proximity  of  the 
transverse  processes  of  the  cervical  vertebrae  make  the  nerve 
secure  from  the  danger  of  wounds  of  pointed  instruments.  It 
is  almost  an  impossibility,  therefore,  for  this  nerve  to  beco 
involved  in  any  form  of  accident,  without  the  large  vessels 
the  neck  being  simultaneously  injured  and  the  patient  sacri- 
ficed. 

Even  in  the  jugular  foramen  the  nerve  is  wrapped  in  t 
same  sheath  as  the  spinal  accessory  nerve^  and  it  is  p 
behind  both  the  glosso-pharyngeal  nerve  and  the  jugulai 
vein ;  while,  to  reach  the  commencement  of  the  common  ca^ 


It 

;5 


i 


SECTION  OF  PNEUM0GA8TRIG  NERVE.  495 

rotid  artery,  the  nerve  is  placed  in  close  relation  to  the  inter- 
nal carotid  artery  and  the  jugnlar  vein. 

As  the  nerves  of  either  side  reach  the  lower  portion  of  the 
neck,  each  takes  a  different  course.  The  right  nerve  passes 
between  the  subclavian  artery  and  vein,  then  along  the  side 
of  the  trachea,  then  to  the  back  of  the  root  of  the  lung,  then 
along  the  side  of  the  oesophagus  as  two  cords,  then  as  a  single 
cord  along  the  back  of  that  tube  through  the  oesophageal 
opening  of  the  diaphragm,  and  terminates  in  the  solar  and 
splenic  plexuses,  after  giving  off  branches  to  the  posterior 
surface  of  the  stomach,  and  some  filaments  to  the  liver.  The 
left  nerve  passes  between  the  left  common  carotid  and  left 
subclavian  arteries  and  behind  the  left  innominate  vein,  then 
arches  across  the  aorta  and  passes  to  the  back  of  the  root  of 
the  lung,  then  as  two  cords  along  the  sides  of  the  oesophagus, 
where  it  joins  with  its  fellow  to  form  the  oesophageal  plexus, 
then,  as  a  single  cord,  in  front  of  the  oesophagus  through  the 
oesophageal  opening  of  the  diaphragm,  when  it  supplies  the 
anterior  surface  of  the  stomach  and  probably  terminates  in 
the  hepatic  plexus. 

THE   EFFECTS   OF   SECTIOi^   OF   THE    PlfEUMOGASTRIC    NERVE. 

The  effects  of  section  of  both  of  the  pneumogastric  trunks,' 

j  if  made  below  the  jugular  ganglion,  are  most  markedly  ex- 

!  hibited  in  the  larynx,  the  lungs,  and  the  heart. 

I       Effects  upon  the  Larynx. — The  larynx  becomes  impaired 

;  in  its  function,  and  the  glottis  remains  partially  closed  by  the 

vocal  cords,  whose  abductor  muscles  are  now  paralyzed,  thus 

impeding  the  free  entrance  of  air  into  the  lung ;  and,  as  a 

consequence  of  this,  the  respirations  are,  for  a  short  time, 

hurried  and  diificult,  although  they  soon  become  diminished 

in  frequency.''    The  inspiratory  effort  becomes  unusually 

I  *  Animals  usually  survive  after  one  vagus  nerve  is  divided,  and  present  only  a  hoarse- 
{  ness  of  voice  ;  an  increased  frequency  of  respiration^  emphysema^  or  pulmonary  congestion 
I  may  be  a  se  ^ucl  to  the  operation.  Union  of  the  divided  nerve  has  been  observed  in 
I  numerous  instances. 

I        ^  Were  it  not  for  the  nerves  of  the  skin,  and  other  sensory  nerves  which  can  transmit 
I  the  feeling  of  pain,  and  which  also  possess  the  power  of  exciting  respiratory  efforts,  sec- 
tion of  both  vagi  ought,  theoretically,  to  stop  respiration  at  once. 


496  THE  CRANIAL  NERVES. 


I 


slow^  while  expiration  is  remarkably  rapid  and  sometimes 
audible  ;  the  intercostal  spaces  sink  inward  during  the  eleva- 
tion of  the  ribs,  showing  that  the  lungs  are  not  fully  inflated 
with  air,  and  death  occurs  in  from  one  to  six  days,  as  the 
result  of  pulmonary  consolidation.  There  are  no  symptoms 
accompanying  the  approach  of  death,  except  a  gradual  fail- 
ure of  respiration  and  a  peculiar  sluggishness,^  which  is  char- 
acteristic and  probably  dependent  upon  carbonic-acid  poi- 
soning. 

The  immediate  cause  of  death  can  undoubtedly  be  attri- 
buted to  the  altered  condition  of  the  lungs,  which  present  a 
state  of  simple  vascular  engorgement^  without  any  apparent  | 
inflammatory  condition  either  of  the  lung  or  pleura.  In  very  ij 
young  animals,  the  division  of  the  vagi  is  followed  by  almost  \ 
immediate  death,  but  this  is  attributable  rather  to  paralysis  | 
of  the  glottis  and  the  ensuing  suffocation  than  to  pulmonary  \ 
congestion,  which  requires  time  for  its  development.  \ 

Effects  upon  the  Lungs. — There  have  been  many  theories  \ 
advanced  to  explain  the  effects  of  division  of  the  pneumo-  ; 
gastric  nerves  upon  the  lung  tissue,  and  particularly  to  ex-  : 
plain  why  such  an  operative  procedure  should  be  followed  by  i 
excessive  pulmonary  hypersemia,  so  as  to  cause  the  specific  \ 
gravity  of  the  lungs  to  exceed  that  of  water.  It  seems  to  me  \ 
that  the  theory,  that  the  entrance  of  secretions  or  food  into  \ 
the  lung  through  the  paralyzed  glottis  (which  can  no  longer  ; 
spontaneously  expel  any  foreign  body)  will  explain  the  con-|  j 
solidation  of  the  lung  as  a  direct  result  of  irritation^  is  not  sus-f  \ 
tained  either  by  the  pathology  of  the  pulmonary  lesion  or  by  ■ 
experiments  where  a  canula  has  been  placed  in  the  larynx  to  : 
prevent  this  cause  of  irritation.  Bernard  has  explained  it  onJ « 
the  ground  that  traumatic  empTiysema  of  the  lung  is  devel-  ; 
oped  from  the  labored  inspiratory  efforts  made  by  the  animal  '\ 
after  the  division  of  the  vagi,  thus  creating  a  mechanical  i 
hcemorrhage  which  eventually  consolidates  the  lung  tissue.  ] 
He  sustains  this  theory  by  the  fact  that  birds,  whose  lungs  j 
are  fixed  and  immovable,  and  are  therefore  inexpansible,  fail  | 

'  The  convulsions  which  often  accompany  asphyxia  are  usually  absent  in  these  animals.      j 


li 


EFFECTS  OF  SECTION  OF  PNEUMOGASTRIG.  497 

I  to  present  this  condition  when  the  vagi  are  divided,  although 

i  death  is  produced. 
i  To  my  mind,  the  most  plausible  explanation  of  the  effects 
of  this  operation  upon  the  lungs  may  be  regarded  as  a  purely 
mechanical  one,  dependent  upon  the  impeded  entrance  of 
air  through  the  larynx.  During  each  inspiratory  effort,  the 
depression  of  the  diaphragm  and  the  elevation  of  the  ribs 
tend  to  create  a  vacuum  within  the  pleural  and  pericardial 
sacs,  and  thus  favor  the  entrance  of  both  air  and  blood  into 
the  thorax.  So  long  as  the  entrance  of  either  one  remains 
unimpeded,  the  proper  balance  between  the  two  is  preserved, 
and  neither  too  much  air  nor  too  much  blood  is  sucked  in  with 
each  inspiration ;  but,  when  the  air  is  prevented  from  enter- 
ing, an  excess  of  blood  flows  into  the  lung  with  each  inspira- 
tion, and,  in  the  course  of  time,  the  lung  is  thus  mechanically 
consolidated.  Were  the  number  of  respirations  not  greatly 
decreased  from  the  normal  standard,  the  duration  of  life 
would  probably  be  proportionally  shortened,  as  the  same 
effect  would  be  produced  in  shorter  time.  The  death  of  birds 
and  some  other  animals,  after  section  of  the  vagi,  may  possi- 
bly be  explained  on  the  ground  of  a  too  powerful  impression 
upon  the  respiratory  center. 

Effects  upon  the  Heart. — In  addition  to  the  effects  upon 
i  the  lungs,  division  of  the  pneumogastric  nerves  is  followed  by 
I  a  marked  alteration  of  the  action  of  the  heart.     The  effects 
!  are  somewhat  similar  to  those  which  might  result  if  the  gov- 
ernor of  a  steam-engine  were  suddenly  removed,  and  the 
piece  of  mechanism  allowed  to  proceed  without  its  control- 
ling influence.     Thus  the  heart  increases  slightly  in  the  rapid- 
ity of  its  pulsations,  and  the  amount  of  cardiac  pressure 
becomes  slightly  diminished^  when  one  of  the  nerves  is  sev- 
ered ;  but,  when  both  are  divided,  the  respiratory  symptoms 
far  outweigh  those  of  the  heart,  but  its  action  is  still  accel- 
erated and  often  irregular,  since  the  inhibitory  power  of  the 
nerves  is  destroyed. 

Effects    upon    the    Digestive    Tract.  —  The    oesophageal 
!  branches  of  the  vagus  are  the  motor  nerves^  which  control  thei 


498  THE  CRANIAL  NERVES, 

jDeristaltic  action  of  that  tube  (as  is  proven  by  the  fact  tha 
division  of  the  pneumogastric  nerves  of  both  sides  causes 
complete  paralysis),  and  also  the  means  by  which  sensation  i 
is  afforded  to  its  mucous  lining.  In  animals  which  havej 
been  subjected  to  division  of  the  vagi,  attempts  to  swallow  ■ 
food  in  any  considerable  quantities  create  a  distention  of ^ 
the  upper  part  of  the  oesophagus,  and  regurgitation  by  means  i' 
of  the  mouth  takes  place  without  the  food  entering  the,' 
stomach,'  as  was  proven  by  Bernard,  who  made  a  gastric 
fistula  in  a  dog  before  dividing  the  pneumogastrics,  in  order  5 
to  decide  this  point.  From  what  source  the  motor  fibers | 
which  control  the  movements  of  the  oesophagus  are  derived  | 
by  the  pneumogastric  nerve  is  still  a  matter  of  doubt ;  the  j 
root  of  the  nerve  itself  seems  to  possess  some  influence  upodjj 
it,  thus  indicating  that  it  can  not  be  traced  to  the  nerves  whicli| 
communicate  with  it  below  the  jugular  foramen.  * 

The  branches  which  are  distributed  to  the  liver  by  the^ 
pneumogastric  nerves  are  probably,  in  some  way,  connected  | 
with  the  glycogenic  function  of  that  organ,  since  division  of 
these  nerves  causes  the  liver  to  yield  no  traces  of  sugar  after 
the  animal  succumbs,  whi(^h  is  contrary  to  the  result  obtained  \ 
after  death  in  animals  which  have  these  nerves  intact.  When  i 
the  nerves  are  divided  in  the  living  animal,  and  the  end  near- 1 
est  to  the  brain  is  galvanized,  an  increase  of  sugar  in  the : 
blood  is  thus  artificially  produced  at  any  time  during  the  life  j 
of  the  animal,  and  traces  of  the  same  may  also  be  found  in  i 
the  urine.  A  similar  hyper-secretion  of  sugar  by  the  livet ! 
may  be  also  noticed  after  the  inhalation  of  irritating  vaporB  i 
or  anaesthetics,  probably  through  the  influence  of  the  vagi. 

The  gastric  branches  of  the  pneumogastrics  show  a  marked  i 
alteration  in  their  power  of  control  over  that  organ  when  thf  ! 
main  nerve  trunks  are  divided.  Tlie  mucous  lining  of  the- 
stomach  becomes  at  once  pale,  and  the  secretion  of  gastric! 
juice  apparently  arrested,  although  a  slight  amount  of  se-i 
cretion  may  return  in  a  few  days  if  the  animal  survive.     Th€»  j 

'  Physiologists  are  not  agi'eed  as  to  the  scat  of  the  reflex  act  of  vomiting  which  fol-  j 
lows  division  of  the  vagi. 


CLINICAL  RELATIONS  OF  PNEUMOGASTRIC  499 

sensations  of  hunger  and  thirst  remain,  but  are  sensibly  di- 
minished.  Absorption  by  the  stomacli  is  evidently  delayed, 
but  not  arrested,  as  has  been  proven  by  the  introduction  of 
poisons  into  that  organ. 

The  intestinal  branches  of  the  vagi  unquestionably  con- 
trol the  secretions  of  the  canal,  and  section  of  the  nerves 
has  been  shown  to  prevent  the  action  of  the  most  powerful 
cathartics,  even  in  fatal  doses,  when  administered  immedi- 
ately before  the  vagi  were  divided.  It  is  still  a  question 
whether  the  pneumogastric  nerves  influence  the  secretions  of 
the  intestinal  canal  directly,  or  through  the  sympathetic  sys- 
tem by  means  of  communicating  filaments. 

If  the  latter  be  the  case,  those  filaments  of  communication 
which  control  the  stomach  and  oesophagus  must  be  sought  for 
high  up  in  the  cervical  region. 

CLINICAL   POII^TS   PERTAII^IKG   TO   THE   PNEUMOGASTRIC   NERVE. 

The  physiological  function  of  the  separate  branches  of  the 
pneumogastric,  as  mentioned  in  preceding  pages,  will  assist 
you  in  appreciating  the  various  manifestations  of  diseased 
conditions  of  the  main  trunk  of  the  vagus,  or  of  its  individual 
branches.  You  can  understand,  from  what  has  previously 
been  said,  that  the  effect  of  degeneration,  section,  or  pressure 
upon  this  important  nerve  must  vary  with  the  seat  of  the 
lesion ;  since  those  branches  given  off  above  the  point  where 
the  nerve  is  impaired  will  manifest  their  usual  powers,  while 
those  given  off  below  that  point  will  show  symptoms  of  par- 
tial or  complete  paralysis.  We  can,  therefore,  study  the  effects 
of  impairment  of  the  pneumogastric  nerve  by  considering  the 
individual  branches  in  their  order  from  above  downward,  and 
recording  the  special  types  of  disease  which  are  liable  to  cre- 
ate symptoms  referable  to  each  branch. 

The  pharyngeal  branch  contains  both  motor  and  sensory 
fibers  ;  hence  injury  to  its  structure  will  create  both  paralysis 
and  anaesthesia,  while  simple  irritation  of  its  fibers  will  tend 
to  create  contraction  or  spasm  of  certain  muscles  to  which 
its  motor  fibers  are  distributed.     We  thus  see,  in  attacks  of 


500  THE  CRANIAL  NERVES.  jj 

hysteria,  the  so-called  '' globus  hystericus, '^^  a  spasmodic  ,1 
affection  of  the  pharynx,  due  to  some  irritation  of  the  ij 
pneumogastric  trunk  or  of  the  pharyngeal  branches.  We  l| 
also  occasionally  meet  true  paralysis  of  this  branch;  in  j 
which  case,  the  act  of  deglutition  is  greatly  impaired,  and,  j. 
if  the  disease  is  bilateral,  swallowing  is  rendered  almost  an  * 
impossibility.  i! 

The  superior  laryngeal  branch,  whose  function  is  to  sup-  j- 
ply  the  mucous  lining  of  the  larynx  with  sensibility,'  becomes,  j 
under  irritation,  the  cause  of  "spasm  of  the  glottis"  and  \ 
of  ''whooping-cough."  The  former  condition,  called  also  1 
'•^  stridulous  Zar2/7^<7^^^5"  and  "Kopp's  asthma,"  is  a  disease  ; 
peculiar  to  children,  which  tends  toward  asphyxia,  but  which  \ 
is  rarely  if  ever  fatal.  It  usually  occurs  during  the  night,  I 
and  seems  to  affect  children  who  have  been  in  apparent  health.  J 
It  is  most  common  during  the  cold  months  ;  is  sometimes  as-  { 
sociated  with  convulsions  ;  and  is  characterized  by  a  sibilant  j 
character  to  the  respiration,  pallor,  or  turgidity  of  the  coun-  '' 
tenance,  and  a  peculiar  retraction  of  the  head.  In  rare  cases,  \ 
this  condition  is  met  with  in  the  adult,  during  attacks  of  hys-  : 
teria.  It  seems  to  be  dependent,  in  children,  upon  dentition,  ; 
digestive  irritation,  anaemia,  rickets,  etc.  \ 

The  experiments  of  Rosenthal  seem  to  point  to  the  superior  j 
laryngeal  nerve  as  the  exciting  cause  of  the  convulsive  cough  j 
of  ''pertussis,^^  and  also  of  that  analogous  cough  often  met  ; 
with  in  hysterical  subjects,  since  artificial  stimulation  of  the  '-. 
nerve  produced,  with  this  observer,  similar  results.  Whether  i 
the  irritation  of  the  nerve  proceeds  from  the  catarrhal  in-  ^ 
flammation  which  exists  in  the  respiratory  passages,  or  irri-  i 
tation  of  some  spinal  or  cerebral  center,  is  not  yet  well  deter-  ; 
mined.  i .; 

The  recurrent  laryngeal  branch  is  of  great  clinical  impor-^  \ 
tance,  since  its  peculiar  course  often  makes  it  a  guide  to  aneu-^^  j 
rism  of  the  large  blood-vessels  by  the  peculiar  symptoms  which  |  \ 


"  See  page  478  of  this  volume. 

'  The  reader  is  referred  by  the  author  to  his  work,  "  A  Treatise  on  Surgical  Diagno 

sis"  (3d  edition,  New  York,  1884),  for  all  the  points  of  diagnosis  of  this  type  of  disease. 


\ 


a 


CLINICAL  RELATIONS  OF  PNEUMOGASTRIG.  501 

it  creates  within  the  larynx.'^  The  so-called  ''brassy  cough" 
is,  by  some  surgeons,  considered  as  pathognomonic  of  press- 
ure upon  or  irritation  of  this  branch,  and  strongly  indicative 
of  aneurism  of  the  subclavian,  carotids,  the  arteria  innomi- 
nata,  or  of  the  left  side  of  the  arch  of  the  aorta. 

This  branch  may  be  affected  by  central  causes,  as  well  as 
by  peripheral  pressure  or  irritation.  As  examples  of  the  cen- 
tral causes  of  impairment  of  this  nerve  may  be  mentioned 
those  cases  of  apoplexy,  cerebral  tumors,  hysteria,  diphthe- 
ria, typhoid  fever,  and  reflex  irritation  from  diseases  of  the 
uterus  or  genitals,  where  the  larynx  is  markedly  affected. 
The  peripheral  causes  which  more  commonly  affect  the  recur- 
rent laryngeal  nerve,  include  catarrhal,  tuberculous,  and 
syphilitic  inflammations  of  the  larynx,  traumatism,  the  press- 
ure of  growing  tumors,  as  aneurism,  goitre,  sarcoma,  cancer, 
lymphatic  tumors,  tumors  of  the  CBSophagus,  etc. 

The  experiments  of  Bernard,  Bischoff,  and  Waller '  (given 
in  some  detail  in  subsequent  pages)  will  help  to  explain  how  a 
lesion,  which  excites  laryngeal  symptoms,  may  occasionally 
be  situated  away  from  the  line  of  the  pneumogastric  nerve, 
since  the  spinal  accessory  nerve  may  be  the  seat  of  irritation 
or  degeneration.  They  will  also  help  to  explain  why  the  ef- 
fects of  bilateral  paralysis  of  the  recurrent  branch  do  not 
produce  dyspnoea,  at  the  same  time  that  it  causes  the  voice 
to  be  lost ;  why  the  vocal  cords  are  seen  to  be  cadaveric  and 
relaxed ;  and  why  the  act  of  coughing  and  the  expulsion  of 
laryngeal  mucus  is  no  longer  possible. 

The  pulmonary  hranches  of  the  nerve  are  unquestionably 
concerned,  to  some  extent,  in  the  conditions  associated  with 
bronchial  spasm,  since  asthma  may  be  developed  by  mental 
influences  acting  upon  the  origin  of  the  vagus.  Moreover,  we 
often  see  severe  types  of  this  disease  produced  by  the  press- 
ure of  thoracic  tumors  upon  the  pneumogastric ;  by  the  in- 
halation of  substances  possessing  slight  irritative  qualities ; 
by  uterine  irritation,  acting  as  a  cause  of  reflex  action  through 
the  pneumogastric  nerve ;  and  by  fright,  shock,  exposure, 

^  See  page  510. 


502  THE  CRANIAL  NERVES. 

etc.     The  symptoms  of  asthma  are  too  well  known  to  be  here  jjj 
repeated. 

We  have  one  other  condition  developed  as  the  effect  of  h 
pressure  upon,  or  destruction  of,  the  vagus,  viz.,  paralysis  of  1] 
the  pulmonary  branches  and  the  consequent  paralytic  condi-  \\ 
tion  of  the  blood-vessels  of  the  lung.     It  is  to  this  condition   - 
that  some  authors  attempt  to  refer  the  serous  infiltration   | 
into  the  parenchyma  of  the  lung  which  follows  section  of  this    : 
nerve ; '  and  we  know,  clinically,  that  a  similar  condition  is 
sometimes  produced  by  compression  of  the  nerve  by  a  tuber- 
culous or  cancerous  degeneration  of  the  lymphatic  glands, 
especially  those  situated  near  to  the  bifurcation  of  the  trachea, 
and  by  aneurism  of  the  thoracic  vessels.     The  same  condition 
has  been  observed  after  injuries  to  the  organs  of  the  chest, 
and  from  the  section  of  some  of  the  branches  of  the  vagus, 
during  an  attempt  to  ligate  the  subclavian  in  its  first  portion 
or  the  arteria  innominata. 

The  cardiac  branches  seem  to  exert  a  more  marked  effect 
upon  the  heart  when  exposed  to  irritation  than  when  actu-  ; 
ally  destroyed  by  degeneration  or  section.  An  artificial  j 
'^ angina  pectoris"  may  be  produced  by  pressure  upon  thesij 
vagus  in  the  neck  (as  performed  by  Czermak  upon  himself),  \ 
and  the  heart's  action  may  thus  be  almost  entirely  arrested,  j 
It  may  be  stated,  I  think,  that  angina  pectoris,  sometimes  ; 
called  ''cardiac  neuralgia,'"'  is  one  of  those  neuroses  of  the  : 
heart  which  depend,  to  a  large  extent,  upon  changes  of  a  \ 
secondary  character  in  the  terminal  filaments  of  the  vagus  or  \ 
the  cardiac  ganglia.  i 

The  symptoms  of  this  affection  are  very  distressing  to  the  ; 
patient,  and  often  fatal.  The  attack  usually  begins  with  ^^ 
sense  of  extreme  constriction  within  the  chest,  which  is  fol-  / 
lowed  by  radiating  pains  of  a  very  intense  character,  which  i 

^  For  the  different  theories  advanced  to  explain  this  effect,  the  reader  is  referred  to   ^ 
page  496  of  this  volume. 

*  I  prefer  to  limit  the  term  "angina  pectoris  "  to  those  cases  only  where  the  exciting 
causes  have  resulted  in  defective  heart  power,  and  to  apply  the  term  "  cardiac  neuralgia  "    i 
to  those  cases  where  the  power  of  the  heart  is  normal.    This  I  consider  to  be  the  true  ,'i 
pathological  distinction.  •  \ 


CARDIALQIA,  BOULIMIA,  POLYDIPSIA.  503 

shoot  down  the  arm  or  into  the  neck.  The  paroxysms  pro- 
duce the  most  rapid  exhaustion,  and  are  not  usually  long 
continued.  The  various  pathological  conditions  found  to 
exist  in  this  affection  include  an  ossified  state  of  the  coro- 
nary vessels  (thus  interfering  with  the  nutrition  of  the  heart 
walls) ;  cardiac  hypertrophy  (which  is  usually  of  that  form 
called  compensatory,  since  the  cavities  of  the  heart  are  gen- 
erally dilated) ;  fatty  degeneration  of  the  heart ;  valvular 
lesions  (with  their  secondary  changes  in  the  size  of  the  cavi- 
ties) ;  and  aneurism  within  the  pericardial  sac. 

The  gastric  branches  of  the  vagus  are  associated  with  the 
conditions  of  gastrodynia  (cardialgia),  boulimia,  polydipsia, 
nervous  vomiting,  and  disorders  of  the  secretory  follicles  of 
the  organ,  as  well  as  its  power  of  absorption.  Gastrodynia  is 
a  paroxysmal  attack  of  neuralgia  of  the  sensory  fibers  of  the 
stomach.  It  produces  pain  of  the  most  intense  character, 
which  often  compels  the  strongest  subjects  to  writhe  in 
agony,  and  to  become  bathed  in  a  profuse  perspiration,  irre- 
spective of  the  temperature  of  the  atmosphere.  The  face 
becomes  bloodless,  the  limbs  cold,  the  abdomen  retracted,  and 
the  pulse  small  and  irregular.  The  attacks  are  usually  of 
short  duration,  and  are  most  frequently  terminated  by  eruc- 
tations and  vomiting.  This  disease  is  met  with  in  hysterical 
and  anaemic  subjects,  in  the  course  of  diseases  of  the  uterus 
and  ovaries,  in  spinal  and  cerebral  affections,  and  in  certain 
dyscrasife. 

An  abnormal  condition  of  hunger,  which  is  appeased  by 
small  quantities  of  food,  but  which  returns  at  frequent  inter- 
vals with  an  uncontrollable  desire,  often  inteiTupting  the 
hours  of  sleep,  is  produced  by  some  disordered  condition 
of  the  vagus,  and  is  called  "  houlimia.^^  This  affection  is 
met  with  in  hysterical  patients,  after  prolonged  fevers,  in 
severe  forms  of  nervous  debility,  in  syphilis,  insanity,  and 
diabetes. 

By  "polydipsia'^  w^e  mean  an  intolerable  thirst,  depend- 
ent upon  an  hypersesthesia  of  the  nerve  fibers  of  the  mucous 
membrane  of  the  stomach,  pharynx,  and  mouth,  and  prob- 


504  THE   CRANIAL  NERVES. 

ably  due  to  some  abnormal  state  of  the  pneumogastric  nerve. 
It  is  often  an  associate  symptom  with  boulimia,  and  is  pro- 
duced by  tlie  same  general  causes. 

The  state  of  ''polyphagia^''  signifies  a  desire  for  excessive 
quantities  of  food.  It  is  supposed  to  exist  when  the  nerve 
fibers  of  the  vagus  distributed  to  the  stomach  are  in  a  state  of 
anaesthesia,  in  contrast  to  the  condition  producing  the  two 
previous  diseases.  It  has  been  found  to  accompany  soften- 
ing of  the  medulla  oblongata,  compression  of  the  roots  of  the 
vagus  by  an  aneurismal  tumor  of  the  vertebral  artery,  atrophy 
of  the  vagi,  neuromata  of  the  vagi,  and  the  morbid  states  of 
epilepsy,  insanity,  and  hysteria. 

The  nervous  voTniting  which  is  clinically  observed  in  con- 
nection with  pregnancy,  chlorosis,  hysteria,  digestive  disturb- 
ances, and  gastrodynia,  is  not  to  be  confounded  with  that  of 
local  diseases  of  the  stomach  or  of  the  alimentary  canal,  since 
the  symptom  depends,  purely  and  exclusively,  upon  some  ab- 
normal condition  of  the  nerves,  rather  than  upon  pathological 
changes  in  the  stomach  or  intestine. 

True  paralysis  of  the  gastric  branches  of  the  vagus  must, 
of  necessity,  arrest  the  peristaltic  movement  of  that  organ, 
and  thus  tend  to  favor  the  retention  of  food  within  its  cavity. 
This  may  be  the  explanation  of  the  enormous  enlargement  of 
the  stomach  found  after  chronic  inflammatory  processes  of 
that  organ,  and  also  as  a  sequel  to  cholera,  typhoid  fever, 
and  some  other  blood  poisons.  The  stomach  becomes  en- 
larged in  these  conditions  mainly  by  the  weight  of  the 
retained  food  and  the  pressure  of  the  gases  formed  by  its 
decomposition. 

The  intestinal  and  hepatic  branches  of  the  vagus  are  not 
well  understood  in  their  clinical  phenomena,  but  the  effects 
of  section  of  the  pneumogastric  seem  to  point  to  some  con- 
trolling influence  of  these  fibers  over  the  glycogenic  function 
of  the  liver  and  the  secretion  of  the  intestinal  juices.  The 
effect  of  diseases  of  the  peritonaeum,  or  of  the  abdominal 
viscera,  upon  the  heart  and  respiration,  is  to  be  explained 
either  as  the  direct  result  of  irritation  of  these  fibers,  or  as  a  i'; 


THE  SPINAL  ACCESSORY  NERVE.  505 

reflex  act  through  the  sympathetic  nerve  upon  the  cardiac 
and  respiratory  centers,  thus  in  turn  affecting  the  heart  and 
lungs  through  the  vagus. 

THE    SPINAL   ACCESSORY,    OR  ELEVENTH   CRANIAL  NERVE. 

This  nerve  has  a  very  extensive  origin,  since  it  derives  its 
fibers  not  only  from  the  medulla  oblongata,  but  also  from  the 
cervical  portion  of  the  spinal  cord.  The  fibers  which  arise 
from  the  medulla  compose  what  is  called  the  ''bulbar  por- 
tion,^^  in  contrast  to  those  which  arise  from  the  cervical  region 
of  the  spinal  cord,  to  which  the  name  of  "  spinal  portion  ^^  is 
sometimes  given.  Such  a  distinction  has  an  importance,  dis- 
tinct from  merely  indicating  the  point  of  origin  of  the  fibers 
composing  the  two  portions  of  the  nerve,  as  the  functions  of 
the  two  are  different. 

If  we  trace  the  filaments  of  origin  of  the  bulbar  portion  of 
the  nerve,  we  can  perceive  that  the  fibers  arise  from  the  lat- 
eral columns  of  the  medulla  oblongata  (its  motor  tract)  and 
escape  from  its  lower  portion,  beneath  the  fibers  of  the  pneu- 
mogastric  nerve.  The  spinal  portion  of  the  nerve  can  be 
traced  between  the  anterior  and  the  posterior  roots  of  the 
first  five  cervical  nerves,  arising  from  between  the  roots  of 
each  nerve  by  a  pair  of  filaments,  with  the  exception  of  the 
last  two,  where  the  filament  going  to  form  the  spinal  accessory 
nerve  is  usually  a  single  one.  These  several  fibers  unite  as 
the  nerve  passes  upward  toward  the  cranium,  thus  causing 
the  spinal  portion  of  the  nerve  to  gradually  increase  in  size. 
In  the  cranium,  the  two  parts  join  to  form  one  nerve,  which 
then  escapes  from  the  jugular  foramen,  in  company  with  the 
pneumogastric  and  glosso-pharyngeal  nerves  and  the  jugular 
vein.  The  inferior  meningeal  artery  enters  the  cavity  of  the 
cranium  through  this  foramen,  and  therefore  bears  a  relation 
to  the  nerves  and  vein. 

The  spinal  accessory  nerve  receives  filaments  of  communi- 
cation with  other  nerves,  even  before  it  escapes  from  the 
cavity  of  the  cranium,  since  the  spinal  portion,  on  its  way 


506 


THE  CRANIAL  NERVES. 


upward  to  unite  with  the  bulbar  portion,  is  joined  by  fila- 
ments derived  from  the  two  upper  cervical  nerves  while  in 
the  spinal  canal. 

After  the  nerve  has  emerged  from  the  jugular  foramen,  it 
gives  off  a  large  branch  to  the  pneumogastric  nerve,  and  occa- 
sionally receives  a  filament  from  the  pneumogastric  in  return ; 


Fig.  143. — Spinal  accessory  nerve.  (Hirschfeld.) 
1,  trunk  of  the  facial  nerve  ;  2,  2,  glosso-phafyngeal  nerve;  3,  3,  pneumogastric;  4,  4,  4, 
t}'unk  of  the  spinal  accessory  ;  5,  sublingual  nerve ;  6,  superior  cervical  ganglion ; 
7,  7,  anastomosis  of  the  first  two  cervical  nerves  ;  8,  carotid  branch  of  the  sympa- 
thetic; 9,  10,  11,  12,  13,  branches  of  the  glosso-pharyngeal ;  14,  15,  branches  of  the 
facial;  16,  otic  ganglion T  17,  auricular  branch  of  the  pneumogastric;  18,^71^5/0- 
mosing  branch  from  iJie  spinal  accessory  to  the  pneumogastric  ;  19,  anastomosis  of  the 
first  pair  of  cervical  nerves  with  the  sublingual ;  20,  anastomosis  of  the  spinal  acces- 
sory with  the  second  pair  of  cervical  nerves  ;  21,  pharyngeal  plexus  ;  22,  superior 
laryngeal  nerve ;  23,  external  laryngeal  nerve ;  24,  middle  cervical  ganglion. 

while,  in  its  course  down  the  neck,  it  receives  filaments  of 
communication  from  the  second,  third,  and  fourth  cervical 
nerves,  in  case  these  nerves  do  not  communicate  with  the 
spinal  portion  vnthin  the  spinal  canal. 

After  the  nerve  has  sent  its  upper  filament  to  the  pneumo 


\\ 


1 


DISTRIBUTION  OF  SPINAL  ACCESSORY. 


507 


gastric,  at  the  jugular  foramen,  it  may  usually  be  perceived 
to  divide  into  two  branches — an  internal  and  an  external ;  the 
former  of  which  anastomoses  directly  with  the  trunk  of  the 
|)neumogastric  nerve,  while  the  latter,  called  the  "muscular 
branch,"  pierces  the  back  part  of  the  upper  third  of  the  sterno- 
mastoid  muscle,  and  terminates  on  the  anterior  surface  of  the 
trapezius.      The  first,    sometimes    called  the    '*  anastomotic 


Fig.  144. — Posterior  vieio  of  the  imiscles  of 
the  larynx.     (Sappey.) 


Fig.  145. — Lateral  view  of  the  muscles  of 
the  larynx.     (Sappey.) 


Fig.  144,-1,  posterior  crico-arytenoid  muscle  ;  2,  3,  4,  different  fasciculi  of  the  arytenoid 
muscle ;  5,  aryteno-epiglottidean  muscle. 

Fig.  145. — 1,  body  of  the  hyoid  bone  ;  2,  vertical  section  of  the  thyroid  cartilage  ;  3,  hori- 
zontal section  of  the  thyroid  cartilage  turned  downward  to  show  the  deep  attach- 
ment of  the  crico-thyroid  muscle  ;  4,  facet  of  articulation  of  the  small  cornu  of  the 
thyroid  cartilage  with  the  cricoid  cartilage  ;  5,  facet  on  the  cricoid  cartilage ;  6, 
superior  attachment  of  the  crico-thyroid  muscle ;  7,  posterior  crico-arytenoid  mus- 
cle; 8,  10,  arytenoid  muscle;  9,  thyro-arytenoid  muscle:  11,  aryteno-epiglottidean 
muscle;  12,  middle  thyro-hyoid  ligament;  13,  lateral  thyro-hyoid  ligament. 

branch,"  is  now  known  to  be  the  nerve  which  supplies  tlie 
muscles  of  the  larynx^  with  the  exception  of  the  crico-thy- 
roid muscle,'  since  physiological  experiment  confirms  this 
distribution. 


'  The  arytenoid  muscle  of  the  larynx  is  supplied  by  both  the  superior  and  recurrent 
laryngeal  nerves,  the  latter  of  which  carry  most  of  the  spinal  accessory  fibers,  as  is 
shown  in  Fig.  140  of  this  volume.    It  is  also  important  to  remember  that  the  investiga- 


508 


THE  CRANIAL  NERVES. 


The  second  branch  communicates  with  the  second  and 
third  cervical  nerves,  before  it  pierces  the  sterno-mastoid 
muscle,  and  its  filaments  undoubtedly  furnish  motor  power 
to  that  muscle  and  also  to  the  trapezius.     It  is  proven  by  ex- 


Fia.  146. — A  diagram  of  the  spinal  accessory  nerve. 

\^i\iQ  accessor}/ portion  ol  the  nerve  arising  from  the  medulla  oblongata;  2,  the  spinal 
portion  of  the  nerve  arising  from  the  spinal  cord  (cervical  region) ;  3.  a  tilament 
arising  from  theirs/  and  second  cervical  nerves  and  joining  the  spinal  portion  of  the 
spinal  accessory  nerve,  before  passing  through  the  foramen  magnum ;  4,  the  fora- 
men magnum,  showing  the  spinal  portion  of  the  nerve  entering  the  cranium ;  6,  the 
jugular  foramen,  showing  the  spinal  and  accessory  portions  of  the  nerve  communi- 
cating as  they  pass  through  it ;  6,  the  large  filament  going  to  the  pneumogastric  to 
supply  the  muscles  of  the  larynx,  and  the  small  filament  returning  to  the  trunk  of  the 
spinal  accessory  nerve ;  7,  8,  9,  filaments  of  communication  between  the  spinal 
accessory  nerve  and  the  third,  fourth,  and  fifth  cervical  nerves ;  10,  muscular  branches 
to  the  sterno-dcido-mastoid  muscle;  il,  muscular  branches  to  the  trapezius  muscle; 
12,  communicating  filaments  from  the  cervical  plexus  of  nci'ves. 


periment,  however,  that  section  of  the  spinal  accessory  nerve 
does  not  produce  total  paralysis  of  these  muscles  ;  and,  from 

tions  of  Bernard  and  BischoflF  have  demonstrated  the  existence  of  other  motor  fibers  to 
the  larynx,  irrespective  of  those  of  the  spinal  accessory,  which  seem  to  control  the  auto- 
matic respiratory  movements  of  the  glottis. 


FUNCTIONS  OF  SPINAL  ACCESSORY  NERVE, 


509 


this  fact,  it  is  conclusively  proved  that  some  other  sources  of 
nerve  supply  to  these  muscles  exist,  besides  the  spinal  acces- 
sory filaments. 

A   TABLE   OP   THE   BRANCHES   OF  THE   SPIJ?"AL   ACCESSOKY   NERVE.' 


r 


The  spinal  ac 
CESSORY,     or  ■{ 
11th   crani- 
al NERVE. 


Accessory  or  bulbar 
PORTION   (by    means  ^ 
of  the  sheath  of  the 
pneumogasiric  n^irve). 


Spinal  portion.  { 


''  Branches  to  t\ie  pharyngeal  plexus, 
Branches  to  the  superior  laryngeal  nerve  (and 

thus  to  the  depressor  nerve  of  the  heart), 
Brandies  to  the  recurrent  laryngeal  nerve  (thus 

supplying  the  muscles  of  phonation). 
Branch  to  the  sterno-masioid  muscle, 
Branch  to  the  trapezius  muscle. 

f  1st  cervical  nerve, 
Communicating  j    2d  cervical  nerve, 
BRANCHES  TO      ]    8d  ccrvical  nerve, 
(^  4th  cervical  nerve. 


FUNCTIONS   OF  THE   SPINAL  ACCESSORY   NERVE   AND  THE   EFFECTS  OF 

SECTION. 

The  experiments  of  Bernard,  to  whose  ingenuity  much  of 
our  present  knowledge  of  the  function  of  the  bulbar  and  spi- 
nal portions  of  this  nerve  is  due,  seem 
to  warrant  the  conclusion  that  the  bul- 
bar or  medullary  part  of  the  nerve  pos- 
sesses a  direct  control  upon  the  mus- 
cles of  the  pharynx  and  larynx^  but 
no  effect  whatever  upon  the  sterno- 
mastoid  and  trapezius  muscles.  Gal- 
vanism of  the  spinal  portion  of  the 
nerve  seems  to  have  a  directly  oppo-  Fig.  uy 
site  effect,  since  the  muscles  of  the 
pharynx  and  larynx  were  unaffected, 
and  the  two  muscles  of  the  neck  to 
which  the  nerve  is  distributed  were 
thrown  into  movement.  It  also  ap- 
pears from  the  results  of  this  great 
experimenter  that  the  nerve  is  essen- 
tially motor  in  Us  function  at  its  ori- 
gin from  the  medulla  and  spinal  cord,  but  that  it  gains  sen- 
sory fibers  after  it  leaves  the  cavity  of  the  cranium,  by  means 


Glottis  seen  tcifh  the  la- 
ryngoscope during  the  emis' 
sion  of  high-pitched  sounds. 
(Le  Bon.) 
1,  2,  base  of  the  tongue ;  3,  4, 
epiglottis ;  5,  6,  pharynx  ;  7, 
arytenoid  cartilages ;  8,  open- 
ing between  the  true  vocal 
cords ;  9,  aryteno-epiglotti- 
dean  folds ;  10,  cartilage  of 
Santorini :  11,  cuneiform  car- 
tilage;  12,  superior  vocal 
cords  ;  13,  inferior  vocal 
cords. 


^  Modified  from  a  table  in  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
nam's  Sons,  New  York,  1880. 
35 


Put- 


510  THE  CRANIAL  NERVES. 

of  certain  filaments  of  communication  derived  from  the  cer- 
vical nerves  and  the  pneumogastric.  This  fact  probably  ex- 
plains why  two  points  of  communication  should  exist  be- 
tween the  spinal  accessory  and  the  pneumogastric  nerves  ; 
since,  at  one  point,  the  sensory  filaments  of  the  pneumogas- 
tric were  given  to  the  spinal  accessory,  while,  at  the  other 
point,  the  motor  filaments  of  the  spinal  accessory  were  sent  to 
the  pneumogastric  sheath  for  protection,  until  they  could  be 
distributed  to  the  muscles  of  the  larynx. 

Bernard  and  Bischoff  have  probably  done  more  to  clear  up 
the  disputed  relation  of  the  spinal  accessory  nerve  to  the  mus- 
cles of  the  larynx,  and  thus  to  the  acts  of  phonation  and  res- 
piration,' than  any  of  the  later  investigators  upon  the  physi- 
ology of  the  nervous  system.   When  the  spinal  accessory  nerve  _ 
is  drawn  out  from  the  medulla  and  spinal  cord  of  an  animal,  |'i 
as  can  be  done  with  little  if  any  injury  to  the  nerve,  if  the  ' ! 
requisite  care  and  skill  be  employed,  the  effect  is  at  once    \ 
manifested  in  the  voice,  which  becomes  hoarse  and  unnatural,    ; 
when  the  nerve  of   one  side  only  is  extracted,  but  entirely   \ 
extinct  when  both  nerves  are  thus  treated.     The  act  of  deglu-    \ 
tition  is  also  somewhat  affected,  and  the  trapezius  and  sterno- 
mastoid  muscles  are  paralyzed,  but  only  to  a  partial  extent. 

An  interesting  relation  of  the  spinal  accessory  nerve  to 
the  action  of  the  heart  seems  to  be  well  shown  by  the  experi- 
ments of  Waller,  who  first  called  the  attention  of  the  profes- 
sion to  the  fact  that  extirpation  of  the  roots  of  the  spinal 
accessory  nerve  produced  a  modification  in  the  effects  of  gal- 
vanism of  the  trunk  of  the  pneumogastric  nerve,  provided 
that  sufficient  time  (soi|ie  two  weeks)  was  allowed  after  the 
operation  for  the  irritation  so  produced  to  subside.  As  has 
been  mentioned  in  the  previous  lecture  upon  the  pneumogas- 
tric nerve,"  galvanism  of  that  nerve  with  a  powerful  current 

will  arrest  the  action  of  the  heart  in  a  state  of  health,  even  if 

• 

'  The  nerves  concerned  in  the  two  acts  of  phonation  and  respiration  are  not  to  bo 
confounded,  since  it  is  probable  that  the  pneumogastric  nerve  sends  filaments  of  a  motor 
character  to  the  larynx,  which  are'  independent  of  the  spinal  accessory  nerve,  and  which 
probably  preside  over  the  respirator)/  movements  of  tho  glottis,  while  the  spinal  accessory 
nerve  controls  phonation.  *  See  page  482  of  this  volume. 


FVJ}^CTIOyS  OF  SPmAL  ACCESSORY  NERVE. 


511 


applied  on  one  side  of  the  body.  Now,  Waller  found  that 
after  the  spinal  accessory  nerve  of  one  side  had  been  drawn 
out,  and  the  animal  allowed  to  recover  the  shock  of  the  opera- 
tion, and  to  wait  some  days  for  all  signs  of  irritation  to  sub- 
side, galvanism  of  the  pneumogastric  nerve  of  the  same  side 
no  longer  seemed  to  affect  the  action  of  the  heart.     The  de- 


Fig.  148. — The  spinal  accessory  nerve.      (Sappey.) 

1,  large  root  of  the  fifth  nerve ;  2,  ganglion  of  Gasser  ;  3,  ophthalmic  division  of  the  fifth  ; 
4,  superior  maxillary  division ;  5,  inferior  maxillary  division  ;  6,  10,  lingual  branch 
of  the  fifth.,  containing  the  filaments  of  the  chorda  tympani ;  Y,  branch  from  the  sub- 
lingual to  the  lingual  branch  of  the  fifth ;  8,  chorda  tympani ;  9,  inferior  dental 
nerve ;  10,  terminal  branches  of  the  gustatory  nerve ;  11,  submaxillary  ganglion  ;  12, 
mylo-hyoid  branch  of  the  inferior  dental  nerve;  13,  anterior  belly  of  the  digastric 
muscle;  14,  section  of  the  mylo-hyoid  muscle;  15,  18,  glosso-pharyngeal  nerve;  16, 
ganglion  of  Andersch  ;  IV,  brattches  from  the  glosso-pharyngeal  to  the  stylo-glossus 
and  the  stylo-pharyngcus  muscles;  19,  19,  pneumogastric;  20,  21,  ganglia  of  the 
pneumogastric ;  22,  22,  superior  laryngeal  nerve ;  23,  spinal  accessory  ;  24,  25,  26, 
27,  28,  sublingual  nerve  and  branches. 

pressor  nerve  of  the  Jieart,  which  arises  from  both  the  supe- 
rior laryngeal  and  pneumogastric  nerves,  since  it  has  two 
heads,  must,  therefore,  be  in  some  way  connected  with  the 


512  THE  CRAKIAL  NERVES. 

spinal  accessory  nerve.  It  may,  therefore,  be  stated  with  as 
much  positiveness  as  any  physiological  point  can  be  laid 
down,  that  the  communicating  filament  given  off  by  the 
spinal  accessory  nerve  to  the  pneumogastric  controls  the 
muscles  of  phonation. 

The  distribution  of  the  spinal  accessory  nerve  to  only  two 
of  the  muscles  of  the  neck — the  sterno-mastoid  and  the  tra- 
pezius— would  naturally  suggest,  to  the  inquiring  mind,  why 
these  muscles  should  have  been  singled  out  as  particularly 
associated  with  this  nerve.  Throughout  this  entire  course  of 
lectures  I  have  frequently  called  your  attention  to  the  fact, 
which  can  not  be  too  often  repeated,  that  the  distribution  of 
nerv,es  to  muscles  always  denotes  a  purpose  on  the  part  of 
Nature,  and  a  similarity  of  function  in  the  muscles  supplied 
by  the  same  nerve,  if  we  will  but  search  for  it.  Now,  we 
have  already  seen  that  the  spinal  accessory  nerve  is  chiefly 
destined  to  control  the  muscles  of  phonation^  since  other 
nerve  fibers  go  to  the  larynx,  which  assist  in  moving  the  vocal 
cords  during  the  opening  of  the  glottis,  previous  to  each  in- 
spiratory act ;  therefore,  the  spinal  accessory  nerve  can  not 
be  said  to  be  directly  concerned  with  the  respiratory  func- 
tion. If  we  will  study  the  attitude  assumed  by  a  vocalist  in 
the  act  of  singing  (and  it  is  in  the  singing  act,  rather  than 
that  of  talking,  that  we  see  the  mechanism  of  phonation  best 
displayed,  since  it  requires  more  of  a  muscular  effort  than 
the  simple  articulation  of  words),  we  shall  perceive  that  the 
sterno-mastoid  and  the  trapezius  muscles  are  important  fac- 
tors in  the  production  of  voice,  as  they  tend  to  fix  the  shoul- 
ders (that  is,  the  scapulae  and  the  clavicles)  and  also  the 
upper  part  of  the  sternum.  In  all  vocal  efforts,  the  first  act 
necessary  to  its  performance  is  a  full  inspiratory  effort,  which 
can  only  be  performed  by  first  calling  into  play>  those  muscles 
which  render  the  upper  portion  of  the  chest  and  the  bones  of 
the  shoulder  immovable,  so  as  to  have  a  fixed  point  from 
which  the  true  inspiratory  muscles  can  act  upon  the  ribs  and 
their  cartilages ;  and  it  can,  therefore,  be  understood  why 
these  muscles  should  properly  be  placed  under  the  control  oi:^. 


RELATION'S  OF  SPIRAL  ACCESSORY  NERVE  TO  VOICE,    513 

that  nerve  which  also  controls  the  muscles  which  regulate 
the  j)osition  and  tension  of  the  vocal  cords  during  the  expira- 
tory effort,  and  thus  causes  the  proper  vibrations  of  these 
cords,  and  regulates  the  note  which  follows. 

In  animals,  where  the  muscular  branch  of  the  spinal  acces- 
sory nerve  has  been  severed,  a  difficulty  in  progression  has 
been  observed  by  Bernard,  and  a  peculiar  sJiortness  of  breath 
after  violent  exercise.  The  difficulty  in  locomotion  is  not 
present  in  man,  on  account  of  certain  anatomical  peculiarities 
which  render  the  arm  unnecessary  for  progressive  motion, 
which  is  not  the  case  with  quadrupeds  ;  but  the  shortness  of 
breath  which  has  been  observed  would  probably  exist  in  a 
man  after  violent  exercise,  or  when  any  demand  for  an  exces- 
sively full  inspiratory  effort  occurred,  if  the  trapezius  or  the 
sterno-mastoid  muscles  were  paralyzed. 

A  theory  advanced  by  Hilton,'  as  explanatory  of  the  pe- 
culiarity of  the  course  of  the  spinal  accessory  nerve,  deserves 
mention,  since  it  tends  possibly  to  explain  not  only  the  irreg- 
ular course  of  the  nerve,  but  also  the  object  of  the  communi- 
cation of  the  sub-occipital  with  the  spinal  accessory  nerves 
within  the  spinal  canal.  According  to  this  author,  the  spi- 
nal portion  of  this  nerve  becomes  joined  to  the  sub-occipi- 
tal before  it  enters  the  cranium,  and,  since  that  nerve  is 
almost  exclusively  a  motor  nerve,  what  object  could  the 
spinal  accessory,  which  is  itself  a  motor  nerve,  have  in  send- 
ing additional  filaments  to  the  sub-occipital,  unless  it  was  for 
the  purpose  of  sending  fibers  to  the  inferior  oblique,  the  two 
posterior  recti,  and  the  complexus  muscles  of  the  neck? 
Now,  when  a  motor  impulse  is  sent  out  by  means  of  the 
spinal  accessory  nerve,  the  effects  reach  those  muscles  first 
which  are  nearest  to  its  place  of  origin ;  hence,  the  muscles 
of  the  sub- occipital  region  are  caused  to  contract  before  the 
trapezius  or  the  sterno-mastoid  muscles,  and,  by  so  doing,  the 
head  is  drawn  backward  before  the  latter  muscles  act,  thus 
greatly  assisting  them  to  raise  the  thorax,  as  well  as  in  ren- 
dering the  head  a  fixed  point  during  the  inspiratory  act. 

1  "Rest  and  Pain,"  London,  1872. 


514  TEE  CRANIAL  NERVES. 

CLINICAL   POINTS   PERTAINING  TO   THE   SPINAL   ACCESSORY   NERVE. 

Like  all  motor  nerves,  the  spinal  accessory  may  exhibit 
the  condition  of  spasm  or  paralysis  in  the  parts  supplied  by 
it ;  if  subjected  to  some  source  of  irritation,  as  in  the  first  in- 
stance, or  to  some  lesion  which  destroys  its  power  of  con- 
duction, as  in  the  latter.  The  spasm  dependent  upon  irrita- 
tion of  this  special  nerve  seems  to  be  confined  exclusively  to 
the  sterno-mastoid  and  trapezius  muscles.  They  may  be  uni- 
lateral or  bilateral,  and  the  muscular  contractions  may  be 
either  of  the  tonic  or  clonic  variety. 

Both  of  these  types  of  spasm  are  met  with  in  connection 
with  reflex  irritation  originating  in  some  of  the  remote  vis- 
cera ;  hence  they  are  not  infrequent  in  severe  types  of  hysteri- 
cal affections.  They  may  also  be  produced  by  diseases  affect- 
ing the  upper  cervical  vertebrae,  by  certain  forced  movements 
of  the  head,  by  exposure  to  cold  and  wet,  and  by  local  dis- 
eases of  the  brain  and  spinal  cord.  When  we  consider  the 
intimate  connection  which  this  nerve  has  with  the  spinal  cord, 
as  well  as  the  medulla  oblongata  and  brain,  we  can  better 
appreciate  the  difficulty  which  often  arises  in  locating  the 
exact  seat  of  the  irritation  which  is  producing  these  spasmodic 
movements.  There  are  reported  cases  to  prove  that  tumors 
of  the  brain  or  spinal  cord,  softening  of  either  of  these  re- 
gions, meningeal  inflammation  of  the  brain  or  cord,  injuries 
to  the  skull  or  upper  cervical  vertebrae,  and  caries,  periostitis, 
and  tumors  of  the  upper  cervical  vertebrae,  may  all  be  excit- 
ing causes  of  this  spasmodic  action. 

Tonic  Spasm  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— When  the  sterno-mastoid  muscle  is  the  seat  of  tonic 
spasm^  the  head  is  so  drawn  that  the  ear  approaches  the 
clavicle,  the  occiput  the  tip  of  the  shoulder,  and  the  chin  is 
so  rotated  that  it  points  toward  the  opposite  side.  This  con- 
dition is  of  longer  or  shorter  duration,  and  often  shows  a 
marked  tendency  to  become  a  permanent  contracture.  Dur- 
ing the  early  paroxysms,  the  patient  can  not  rectify  the  dis- 
placement of  the  head  by  his  own  voluntary  efforts,  and  pas- 


CLINICAL  RELATIONS  OF  SPINAL  ACCESSORY  NERVE.    515 

sive  motion  is  strongly  resisted.  Tlie  early  periods  of  tlie 
paroxysm  are  often  accompanied  by  sharp  pains.  When  the 
disease  has  become  chronic,  the  deformity  of  the  neck  is  as- 
sociated with  2i permanent  curvature  of  the  cermcal  xertehrce 
and  a  corresponding  curve  of  a  compensatory  character  in  the 
dorsal  and  lumbar  regions.  A  rare  case  of  bilateral  tonic 
spasm  of  the  sterno-mastoid  muscles  is  reported  by  Duchenne, 
in  which  the  chin  was  approximated  to  the  breast. 

The  trapezius  muscle  may  also  be  the  seat  of  tonic  spasm. 
In  this  case,  the  head  is  inclined  toward  the  affected  side, 
the  occiput  is  drawn  toward  the  shoulder,  the  shoulder  itself 
is  raised,  and  the  scapula  is  drawn  inward.  The  chin  is  not 
rotated  toward  the  unaffected  side,  as  in  the  case  of  the 
sterno-mastoid  muscle.  All  attempts  to  bring  the  head  into 
its  proper  relation  to  the  trunk  create  a  rigidity  and  sensi- 
tiveness over  the  region  of  the  trapezius. 

Clonic  Spasm  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— This  variety  of  spasm,  which  is  dependent  upon  the 
same  general  list  of  causes  as  the  tonic  form,  may  be  uni- 
lateral or  bilateral.  Either  of  the  muscles  supplied  by  the 
spinal  accessory  may  be  affected  alone,  or  the  sterno-mastoid 
and  trapezius  may  contract  alternately.  If  the  spasm  be  con- 
fined to  one  muscle  and  of  the  unilateral  type,  the  deflection 
of  the  head  will  be  the  same  as  in  the  tonic  spasm,  except 
that  the  duration  of  the  contraction  will  be  for  a  shorter 
period,  and  of  a  convulsive  variety  ;  while,  if  the  two  muscles 
of  one  side  contract  alternately,  the  attitude  of  the  head  will 
be  constantly  changing  from  the  condition  due  to  contraction 
of  the  one  to  that  produced  by  the  other.  When  the  sterno- 
mastoid  muscles  of  both  sides  act  simultaneously  in  a  spas- 
modic contraction,  a  peculiar  ''nodding  movement"  is  per- 
ceived. You  can  understand  how  all  forms  of  combina- 
tions can  be  made  between  the  two  muscles  of  either  side, 
and  a  proportionate  variety  of  spasmodic  attitudes  will  be 
the  result.  All  of  these  contractions  occur,  for  the  most 
part,  in  paroxysms^  often  lasting  for  a  day,  and  not  infre- 
quently coming  on  with  such  violence  and  frightful  vehe- 


516  THE  CRANIAL  NERVES. 

mence  that  the  head  is  tossed  to  and  fro  mth  great  force, 
making  the  life  of  the  patient  miserable.  In  some  instances, 
the  spasm  is  almost  continuous.  Sleep,  however,  usually 
brings  rest,  though  this  is  often  prevented  or  delayed. 

In  unilateral  clonic  spasm  of  the  stemo-mastoid  muscle, 
the  adjacent  muscles  of  the  face,  jaw,  and  arm  are  occasional- 
ly thrown  into  simultaneous  action.  The  scaleni  muscles  are 
also  sometimes  brought  into  active  play,  and  their  forcible 
compression  of  the  brachial  plexus  of  nerve  and  the  veins 
of  the  neck  has  been  known  to  result  in  stiffness,  anaes- 
thesia, and  oedema  of  the  arm,  after  such  an  attack  had  sub- 
sided. 

The  nodding  movement  produced  by  the  bilateral  clonic 
spasm  of  the  sterno-mastoid  muscles  is  sometimes  called  the 
*' salaam  convulsion  of  Newnham."  It  is  rarely  seen  in 
adults,  but  in  children  it  is  not  infrequent.  Should  it  occur 
during  dentition,  the  spasm  may  be  associated  with  convulsive 
movements  of  the  facial  muscles,  with  strabismus,  and  even 
with  general  convulsions  and  a  loss  of  consciousness.  Bi- 
lateral spasm  of  the  muscles  supplied  by  the  spinal  accessory 
nerve  has  been  known  to  terminate  in  epilepsy,  insanity,  and 
paralysis ;  and,  when  the  various  causes  of  the  condition  are 
reviewed,  this  will  appear  but  the  natural  sequence  of  the 
further  progress  of  some  of  the  diseases  mentioned.  Should 
reflex  irritation,  as  in  dentition,  worms,  hysteria,  etc.,  exist, 
or  the  spasm  be  dependent  upon  rheumatic  origin,  exposure 
to  cold  or  dampness,  traumatism,  caries,  and  other  curable 
conditions,  the  results  will  be  arrested  when  the  exciting 
cause  has  been  removed. 

Paralysis  of  the  Sterno-mastoid  and  Trapezius  Mus- 
cles.— These  muscles  may  be  affected  with  a  total  arrest 
of  their  nerve  power  by  lesions  of  the  motor  columns  of  the 
spinal  cord,  resulting  in  progressive  muscular  atrophy ;  by 
fracture  of  the  cervical  vertebrae ;  diseases  of  the  vertebrae 
near  the  skull  and  also  of  the  cranial  bones  ;  injuries  to  the 
nerve,  such  as  cuts,  stabs,  gunshot  wounds  of  the  neck ;  and 
compression  of  the  nerve  from  peripheral  causes,  as  in  the 


CLINICAL  RELATIONS  OF  SPINAL  ACCESSORY  NERVE.    517 

case  of  tumors  of  the  neck,  swelling  of  the  lymphatic  glands 
of  the  neck,  abscesses,  neuromata,  etc. 

The  sterno-mastoid  or  the  trapezius  may  be  paralyzed  in- 
dependently of  the  other,  or  they  may  both  be  affected  si- 
multaneously, according  as  the  cause  affects  the  entire  nerve  or 
only  some  individual  branch.  The  paralysis  may,  in  some 
instances,  be  bilateral,  provided  the  exciting  cause  be  central 
and  involve  the  parts  in  the  median  line,  or  so  extensive  as  to 
press  upon  the  trunks  of  both  spinal  accessory  nerves.  A 
case  of  bilateral  paralysis  following  progressive  muscular 
atrophy  of  the  muscles  of  the  neck  is  reported  by  Rosenthal, 
where  the  patient  was  obliged  to  support  the  head  by  a  collar 
made  of  pasteboard  ;  but  this  was  rather  the  consequence  of 
the  general  atrophy  of  the  muscles  than  the  effect  of  the  pa- 
ralysis of  the  two  muscles  supplied  by  the  spinal  accessory. 

In  unilateral  paralysis  of  the  sterno-mastoid  muscle.,  the 
voluntary  potation  of  the  head  toward  the  unaffected  side  is 
performed  with  difficulty  ;  the  chin  is  turned  toward  the  af- 
fected side,  on  account  of  the  unopposed  action  of  the  healthy 
muscle  ;  the  chin  is  also  slightly  elevated,  and  the  paralyzed 
muscle  does  not  stand  out  with  equal  prominence  with  its 
fellow,  when  the  chin  is  supported  by  the  hand  of  the  physi- 
cian, and  direction  is  given  to  the  patient  to  try  and  depress 
the  chin  toward  the  chest.  If  this  unilateral  paralysis  be 
long  continued,  the  contracture  of  the  healthy  muscles  pro- 
duces the  condition  of  ''  torticollis." 

When  a  bilateral  paralysis  of  the  sterno-mastoid  muscles 
is  developed,  the  head  is  held  straight,  and  its  rotation,  es- 
pecially with  the  chin  elevated,  is  performed  with  extreme 
difficulty.  The  neck  appears  thin,  and  the  lateral  aspect  of 
that  region  is  markedly  flattened,  since  the  normal  prominence 
of  the  sterno-mastoid  muscle  is  wanting.  The  same  test,  as 
mentioned  above,  when  the  chin  is  supported  by  the  hand  of 
the  physician,  shows  a  great  loss  of  power  in  attempting  to 
flex  the  head  upon  the  chest. 

The  effects  of  unilateral  paralysis  of  the  trapezius  mus- 
cle are  most  marked  in  the  region  of  the  scapula.     This  bone 


518  THE  CRANIAL  NERVES, 

appears  to  be  drawn  downward  and  forward  ;  its  inferior  angle 
lies  closer  to  the  vertebral  column  than  that  of  its  fellow,  and 
its  upper  part  is  more  widely  separated  from  the  vertebra. 
The  clavicle  is  caused  to  stand  off  from  the  chest,  on  account 
of  the  acromion  being  drawn  downward  and  forward  by  the 
weight  of  the  upper  extremity  and  the  pectoral  and  the  leva- 
tor anguli  scapulae  muscles ;  hence,  the  supra-clavicular  fossa 
is  apparently  enlarged,  in  comparison  with  the  healthy  side. 
It  is  to  be  remembered,  however,  by  you  that  the  trapezius, 
unlike  many  others  in  the  body,  often  manifests  paralysis  in 
portions  of  the  muscle  ;  so  that  the  symptoms  of  this  type  of 
unilateral  paralysis  admit  of  many  modifications,  in  accord- 
ance with  the  extent  and  limits  of  the  disease.  Thus,  the 
position  of  the  scapula  will  vary  Avith  the  paralysis  of  the 
upper,  middle,  or  lower  fibers  of  the  muscle ;  the  power  of 
elevation  of  the  arm  will  be  greatly  impaired  if  the  upper 
fibers  are  paralyzed  ;  while  the  approximation  of  the  scapula 
to  the  vertebral  column  is  very  much  impaired  when  the 
middle  fibers  are  alone  involved. 

When  the  trapezei  muscles  are  affected  with  bilateral 
paralysis,,  in  addition  to  the  symptoms  described,  which  will 
now  be  perceived  upon  both  sides,  the  hack  will  appear 
broader  and  more  arched^  since  the  scapulae  are  lowered  and 
drawn  outward,  while  they  are  also  more  prominent.  Some 
difficulty  may  also  be  experienced  in  maintaining  the  head  in 
an  upright  position,  since  it  naturally  tends  to  sink  toward 
the  chest. 


THE  HYPO-GLOSSAL,   OR  TWELFTH  CRANIAL  NERVE. 

This  nerve  is  sometimes  called  the  sublingual  nerve^  thus 
using  a  Latin  rather  than  a  Greek  term  to  express  the  same 
idea,  viz.,  that  the  nerve  passes  underneath  the  tongue.  It  is 
the  last  of  the  cranial  nerves,  and  is  intimately  associated  w  ith 
all  those  movements  in  which  the  tongue  takes  an  important 
part,  such  as  the  acts  of  talking,  singing,  mastication,  and 
deglutition.     The  point  of  external  origin  of  this  nerve  is  a 


THE  HYPO-GLOSSAL,    OR   TWELFTH  NERVE. 


519 


groove  between  the  olivary  body  of  tlie  medulla  oblongata 
and  the  anterior  pyramid^  below  the  point  of  escape  of  the 
ninth,  tenth,  and  eleventh  nerves.  Its  deep  fibers  can  be 
traced  to  a  nucleus  in  the  floor  of  the  fourth  ventricle.  The 
reader  is  referred  to  those  pages  of  the  previous  section 
which  treat  of  the  medulla  oblongata  for  further  informa- 
tion. The  nerve  escapes  from  the  cavity  of  the  cranium  by 
the  anterior  condyloid  foramen. 


Fig.  149. — Distribution  of  the  hypo-glossal  nerve,     (Sappey.) 

1,  root  of  the  fifth  nerve;  2,  ganglion  of  Gasser ;  3,  4,  5,  6,  7,  9,  10,  12,  branches  and 
anastomoses  of  the  fifth  nerve  ;  11,  submaxillary  ganglion;  13,  anterior  belly  of  the 
digastric  muscle ;  14,  section  of  the  mylo-hyoid  muscle  ;  15,  glosso-pharyngeai  nerve ; 
16,  ganglion  of  Andersch ;  17,  18,  branches  of  the  glosso-pharyngeai  nerve;  19,  19, 
pneumogastric ;  20,21,  ganglia  of  the  pneumogastric ;  22,  22,  superior  laryngeal 
branch  of  the  pneumogastric  ;  23,  spinal  accessory  nerve ;  24,  hypo-glossal  nerve;  25, 
descendens  noni  ;  26,  thyro-hyoid  branch  ;  27,  terminal  branches  ;  28,  two  branches^ 
one  to  the  genio-hyo-glossus  and  the  other  to  the  genio-hyoid  muscle. 


After  the  nerve  escapes  from  the  cranium,  it  gives  a  fila- 
ment of  communication  to  the  sympathetic  nerve,  which  joins 


520 


THE  CRANIAL  NERVES. 


the  superior  cervical  ganglion  ;  another  to  the  jpneumo gastric 
nerm ;  two  or  three  branches  to  the  upper  cervical  nerves ; 


Fig.  160. — Anastomotic  hop  formed  by  the  descending  branch  of  the  hypo-glossal  and  the 
internal  descending  branch  of  the  cervical  plexus.     (After  Hirschfeld.) 

1,  lingual  nerve  passing  transversely  upon  the  hyo-glossus  muscle ;  2,  2,  trunk  of  the 
pneumogastric ;  3,  superior  laryngeal  nerve ;  4,  external  laryngeal  nerve ;  5,  external 
branch  of  the  spinal  accessory  supplying  the  sterno-mastoid  and  trapezius ;  6,  ante- 
rior branch  of  the  second  pair  of  cervical  nerves ;  7,  anterior  branch  of  the  third 
pair ;  8,  anterior  branch  of  the  fourth  pair ;  9,  origin  of  the  phrenic ;  1 0,  origin  of 
the  subclavian  nerve;  11,  origin  of  the  anterior  thoracic  nerves  of  the  brachial 
plexus;  12,  middle  portion  of  the  trunk  of  the  hypo-glossal;  13,  descendens  noni ; 
14,  internal  descending  branch  of  the  cervical  plexus,  forming,  with  the  preceding,  a 
loop  with  its  convexity  directed  downward  ;  16,  inferior  branch  from  this  loop,  sup- 
plying the  sterno-thyroid  muscle ;  1 6,  superior  branch  distributed  to  the  sterno-hyoid 
muscle;  17,  another  branch  still  higher  up,  and  distributed  to  the  same  muscle; 
18,  middle  branches  from  the  loop ;  19,  filament  extending  as  far  as  the  lower  ex- 
tremity of  the  sterno-thyroid  ;  20,  branch  given  off  by  the  hypo-glossal  to  the  thyro- 
hyoid ;  21,  branches  of  anastomosis  between  the  hypoglossal  and  lingual;  22,  ter- 
minal portion  of  the  trunk  of  the  hypo-glossal. 


and,  finally,  a  communicating  branch  to  the  gustatory  branch 
of  i\LQ  fifth  nerve. 


DISTRIBUTION  OF  EYPO-GLOSSAL  NERVE,  521 


Fig.  151. — A  diagram  of  the  hypoglossal  and  its  branches, 

trunk  of  hypo-glossal  nerve,  escaping  from  the  medulla  oblongata ;  2,  anterior  condi/loid 
foramen ;  3,  filaments  of  communication  to  the  pneumogastric  nerve  ;  4,  filaments  of 
communication  to  the  supei'ior  cervical  ganglion  of  the  sympathetic  system  ;  5,  fila- 
ments of  communication  to  the  first  and  second  spinal  nerves  of  the  cervical  region ; 
6,  the  descendens  noni  nerve,  forming  a  loop  with  the  communicans  noni  nerve  (19) 
and  giving  off  muscular  branches  from  the  loop  ;  7,  muscular  filaments  to  the  thyro- 
hyoid muscle  ;  8,  muscular  filament  to  the  geniohyoid  muscle  ;  9,  muscular  fila- 
ment to  the  genio-hyo-glosstis  muscle  ;  10,  muscular  filament  to  the  hyo-glossus  muscle  ; 
11,  muscular  filament  to  the  stylo-glossus  muscle;  12,  the  occipital  artery,  around 
which  the  hypo-glossal  nerve  winds,  before  reaching  the  tongue  ;  18,  a  branch  of  the 
communicans  noni  nerve,  derived  from  the  second  cervical  nerve ;  14,  a  branch  of 
the  communicans  ?iom' nerve,  derived  from  the  third  cervical  nerve  ;  15,  a  muscular 
branch  to  the  omo-hyoid  muscle  (anterior  belly);  16,  a  muscular  branch  to  the  sterno- 
hyoid muscle;  17,  a  muscular  branch  to  the  sterno-ihyroid  m\xs>c\e  \  18,  a  muscular 
branch  to  the  omo-hyoid  (posterior  belly) ;  19,  the  communicans  noni  nerve.  Joining 
the  descendens  noni  nerve  to  form  a  loop. 


522 


THE  CRANIAL  NERVES. 


Its  first  branch  of  distribution  is  named  the  descendens 
noni  (the  descending  of  the  ninth  nerve),  so  called  since  this 
nerve  was  classed  by  Willis  as  the  ninth.  This  branch 
passes  down  the  neck  to  supply  the  stemo-hyoid,  sterno- 
thyroid, and  omo-hyoid  muscles,  and  then  joins  the  com- 
Tnunicans  noni  nerve  (a  branch  of  the  cervical  plexus),  to 
form  a  loop,  from  which  terminal  filaments  are  given  off. 
The  other  branches  of  the  nerve  are  distributed  to  the  thyro- 
hyoid muscle  (which  usually  has  a  separate  filament  of  its 
own),  the  stylo -glossus,  the  hyo-glossus,  genio-hyoid,  genio- 
hyo-glossus,  and  the  intrinsic  muscles  of  the  tongue.  It  will 
thus  be  seen  that  the  hypo-glossal  nerve  is  the  motor  nerve  of 
all  the  muscles  which  tend  to  depress  the  larynx  and  the 
hyoid  hone,  after  they  have  been  raised  during  the  second 
stage  of  the  act  of  deglutition  (the  muscles  of  the  infra-hyoid 
region),  also  to  one  of  the  supra-hyoid  region,  the  genio-hy- 
oid, and  to  most  of  the  muscles  which  act  upon  the  tongue. 

In  the  preceding  diagrammatic  figure,  the  branches  of  the 
hypo-glossal  nerve  are  shown,  and  the  general  course  of  the 
nerve  is  made  more  clear  than  can  be  done  by  a  verbal  de- 
scription. 


TABLE   OF  THE   BRANCHES   OF  THE   HYPO-GLOSSAL   NERVE.' 


THE  HYPO-GLOSSAL, 
OR  TWELFTH  CRA- 
NIAL NERVE. 


Branches  of 
communication. 


Branches  of 
distHbuiion. 


(  To  the  ganglion  of  the  trunk  of  the  pneu- 

mogastrie  nerve, 
To  the  superior  cervical  ganglion  of  the 

sympathetic, 
To  the  loop  between  the  first  and  second 

cervical  nerves, 
To  the  gustatory  nerve. 
Descendens  noni  nerve, 
To  thyro-hyoid  nerve, 
To  genio-hyoid  muscle, 
To  stylo-glossus  muscle, 
To  hyo-glossus  muscle, 
To  genio-hyo-glossus  muscle, 
To  the  intrinsic  muscles  of  the  tongue. 


FUNCTIONS   OF  THE  HYPO-GLOSSAL  NERVE. 

The  fact  that  the  hypo-glossal  nerve  arises  from  the  motor 
portion  of  the  spinal  cord  (when  taken  in  connection  with  the 


'  Copied  from  the  "  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
New  York,  1880. 


Putnam's  Sons, 


FUNCTIONS  OF  THE  HYPO-GLOSSAL  NERVE.  523 

absence  of  any  ganglionic  enlargement  upon  the  trunk  of  the 
nerve)  would  seem  to  indicate  that  the  function  of  the  hypo- 
glossal is  essentially  motor ;  and  such  a  conclusion  is  sus- 
tained by  the  experiments  of  Longet,  who  found  the  nerve 
incapable  of  transmitting  any  sensory  impressions  when  the 
roots  were  subjected  to  irritation. 

Mayo  and  Magendie,  however,  first  proved  that  the  nerve 
possessed  sensory  filaments,  after  it  had  escaped  from  the 
cavity  of  the  cranium,  which  results  have  since  been  confirmed 
by  most  of  the  later  physiologists.  We  can  easily  explain 
this  acquired  power  of  sensibility  which  the  nerve  exhibits, 
by  the  branches  of  communication  which  it  receives  from  the 
pneumogastric,  the  cervical  nerves,  and  the  gustatory  branch 
of  the  fifth  nerve ;  so  that  there  is  little,  if  any,  reason  to 
doubt  that  the  original  fibers  of  the  nerve  itself  are  purely 
motor  in  function. 

In  connection  with  the  glosso-pharyngeal  nerve,  I  entered 
into  a  somewhat  extended  discussion  of  the  mechanism  of  the 
act  of  deglutition  ;  ^  and  the  same  subject  might,  with  equal 
propriety,  be  again  repeated  in  connection  with  the  hypoglos- 
sal nerve,  since  both  are  intimately  associated  with  those 
complex  movements.  It  will  suffice,  however,  to  again  call 
attention  to  the  fact,  that  moa)ements  of  the  tongue  were  of 
the  greatest  importance  in  swallowing,  since  that  organ  not 
only  conveyed  the  bolus  to  the  back  portion  of  the  mouth, 
and,  when  liquids  were  to  be  swallowed,  helped  to  form  a 
tube  through  which  a  suction  force  could  be  exerted,  but  also 
assisted  in  the  prevention  of  food  from  entering  the  cavity  of 
the  larynx. 

CLIN^ICAL  POII^TS   PERTAI:N^I2^G   TO  THE   HYPO-GLOSSAL  KERVE. 

When  this  nerve  is  divided  in  animals,  the  sense  of  taste 
remains  and  the  tongue  retains  its  normal  sensitiveness ;  but 
the  power  of  movement  is  utterly  destroyed  if  the  nerves  of 
both  sides  are  simultaneously  cut.  As  a  natural  consequence, 
the  first  stage  of  the  act  of  deglutition  is  materially  embar- 

^  See  page  4*72  of  this  volume. 


524 


THE  CRAmAL  NERVES. 


rassed,  and  the  second  stage  is  liable  to  be  associated  with  the 
entrance  of  fluid,  if  swallowed,  into  the  cavity  of  the  larynx. 
When,  in  the  human  subject,  this  nerve  is  impaired,  either 
as  a  special  type  of  paralysis  or  during  an  attack  of  hemi- 
plegia, the  power  of  protrusion  of  the  tongue  from  the  mouth 
in  a  straight  line  is  lost,  and  that  member  becomes  de- 
flected toward  the  side  which  is  paralyzed,  since  the  genio- 
hyo-glossus  muscle  is  unopposed.  A  disease  of  rather  rare 
occurrence,  in  which  the  hypo-glossal  nerves  of  both  sides  are 
paralyzed,  and,  in  addition,  the  orbicular  muscle  of  the  mouth, 
and,  not  infrequently,  the  intrinsic  muscles  of  the  larynx,  is 
described  by  Duchenne  ; '  and,  since  his  article,  it  has  been 


Fig.  162. —  Glosso-lahio-laryngeal  paralysis.     (After  Hammond.) 


written  upon  by  most  of  the  later  authors  under  the  names 
of  glosso-labio-laryngeal  paralysis,  glossoplegia,  etc.  In  this 
type  of  disease  the  tongue  lies  motionless  and  trembling  in  the 

1  "De  I'electrisation  localisde,"  Paris,  1861. 


BUGHENNE'S  DISEASE.  625 

floor  of  the  mouth,  if  all  power  of  motion  be  paralyzed ;  but, 
if  paresis  only  exist,  it  can  be  imperfectly  protruded  with 
difficulty,  and  is  tremblingly  and  slowly  retracted.  If  one 
side  be  affected,  the  sound  side  becomes  full  and  promi- 
nent, in  comparison  with  the  affected  side,  when  called  into 
action.  The  peculiar  trembling  character  of  the  move- 
ment of  the  tongue  in  bilateral  paresis  is  observed  in  every 
motion  which  the  patient  attempts  to  perform  with  that  or- 
gan, and  all  the  motions  are  slowly  and  imperfectly  accom- 
plished. 

The  most  important  effects  of  the  paralytic  state  of  the 
muscles  are  shown  in  attempts  at  mastication  and  speech. 
The  food  is  no  longer  properly  placed  between  the  teeth ;  is 
with  great  difficulty  carried  to  the  back  part  of  the  mouth ; 
and  frequently  regurgitates  into  the  mouth,  when  attempts 
are  made  to  swallow.  The  saliva  is  secreted  in  large  quanti- 
X  ties,  and  is  swallowed  with  extreme  difficulty,  so  that  the 
patient  is  constantly  obliged  to  expectorate. 


Fig.  153. —  Glosso-labio-laryngeal  paralysis.     (After  Hammond.) 

The  disturbances  of  speech  may  present  themselves  with 
varying  degrees  of  intensity.  In  those  cases  where  the  tongue 
is  affected  upon  one  side  only  (and  a  state  of  paresis  exists, 
rather  than  that  of  complete  paralysis  of  motion),  only  those 
sounds  which  require  the  aid  of  the  tongue  to  be  pronounced 

36 


526  THE  CRANIAL  NERVES. 

are  indistinctly  and  incompletely  articulated.  These  letters 
are  5,  sJi^  Z,  e,  ^,  and,  at  a  later  period,  k,  g^  r,  etc. 

When  the  paralysis  is  bilateral,  and  the  tongue  has  under- 
gone atrophy,  the  speech  becomes  exceedingly  indistinct, 
muttering  and  inarticulate,  so  that  the  patient  can  hardly 
express  himself  in  sounds  that  can  be  understood  by  those  in 
constant  communication  with  him.  The  act  of  singing  is 
always  affected  in  even  the  mild  forms  of  lingual  paralysis  ; 
and  the  falsetto  notes  are  particularly  affected,  since  the 
tongue  plays  an  important  part  in  so  directing  the  sound  as 
to  give  it  its  proper  timbre. 

The  effects  of  lingual  paralysis  must  not  be  confounded 
with  spasm  of  the  lingual  muscles  (the  act  of  stuttering),  or, 
on  the  other  hand,  with  dumbness  and  aphonia. 

In  some  cases  of  Duchenne's  disease,  the  lips  are  not  af- 
fected ;  while,  in  others,  the  laryngeal  and  pharyngeal  mus- 
cles are  not  impaired  to  a  sufficient  degree  to  cause  any 
serious  impediment  to  their  normal  functions.  We  can 
the  better  understand  why  all  possible  varieties  and  degrees 
of  paralysis  may  exist  in  this  disease  when  we  consider  that, 
in  order  to  account  for  all  the  symptoms  present  in  a  fully 
developed  case,  the  facial,  spinal  accessory ,  pneumogastric, 
and  hypo-glossal  nerves  must  be  simultaneously  diseased, 
or  subjected  to  extreme  pressure.  Should  the  facial  nerve 
escape,  the  lips  and  face  will  preserve  their  normal  power; 
if  the  spinal  accessory  nerve  be  unimpaired,  the  larynx  may 
escape,  provided  that  the  pneumogastric  nerve  remain  intact 
below  the  point  of  communication  between  these  two  nerves  ; 
if  the  hypo-glossal  nerve  be  normal,  the  symptoms  referable 
to  the  tongue  would  not  be  detected.  The  essential  lesion  of 
this  disease  seems  to  consist  of  a  degeneration  of  the  medulla 
oblongata  and  the  upper  portion  of  the  spinal  cord ;  hence 
the  nuclei  of  origin  of  the  facial,  spinal  accessory,  pneumo- 
gastric, and  hypo-glossal  nerves  are  liable  to  be  involved  to  a 
greater  or  less  extent  simultaneously.  Whether  the  view  of 
Leyden,  that  the  condition  is  one  of  myelitis,  will  be  sus- 
tained, is  still  uncertain,  but  that  the  condition  closely  re- 


GLOSSO-LABIO-LARYNGEAL  PARALYSIS.  527 

sembles  that  which  creates  the  spinal  paralysis  of  the  infant 
and  adult  seems  positive. 

The  previous  existence  of  the  early  manifestations  of  syph- 
ilis and  the  probable  activity  of  the  disease  in  the  system 
may  account  for  the  lesion  in  some  cases,  while  in  others  the 
rheumatic  diathesis,  mental  anxiety,  and  excessive  mental 
application,  *  seem  to  have  acted  as  exciting  causes. 

The  general  paralysis  of  the  insane  often  first  manifests 
itself  in  a  peculiar  weakness  of  the  tongue  and  lips. 

The  tremor  of  paralytic  dementia  probably  first  makes  its 
appearance  in  the  facial  and  lingual  muscles.  It  consists  in 
non-rhythmical  contractions  of  small  muscles  or  of  fasciculi  of 
muscles,  which  are  either  present  in  the  quiescent  state  of  the 
features,  or  are  excited  by  emotion  or  by  the  performance 
of  a  voluntary  movement,  as  showing  the  tongue  or  teeth. 
Sometimes  innumerable  fine,  fibrillary  tremors  cover  the  face, 
while,  in  some  cases,  the  movements  are  coarser,  and  irregular 
enough  to  merit  the  term  choreic.  The  tongue  exhibits  both 
sets  of  tremors — the  very  fine  fibrillary  ones  and  the  large 
choreic  oscillations.  There  is,  also,  though  usually  at  a  later 
stage,  some  shriveling  or  atrophy  of  the  tongue.  I  quote 
from  a  late  article  of  Professor  E.  C.  Seguin,'  as  follows  : 

"The  hands  are  tremulous,  usually  in  a  fine,  semi-rhyth- 
mical way.  This  trembling  is  sometimes  scarcely  visible, 
but  is  perceptible  as  a  delicate  parchment-like  fremitus  on 
holding  up  the  patient's  extended  fingers  between  ours.  In 
the  lower  extremities  the  tremulousness  is  not  apparent. 

"The  speech  is  affected  as  a  result  of  this  tremor,  and  as 
the  result  of  a  certain  want  of  coordination  in  the  muscles  of 
articulation.  Words  are  quickly  spoken,  with  some  syllables 
omitted  or  blurred,  or  with  a  terminal  syllable  left  off.  The 
articulate  sounds  which  are  produced  are  heard  as  vibratory 
or  tremulous,  and  the  speech  seems  thick.  Patients  semi-un- 
consciously  avoid  long  or  difl3.cult  words  in  conversation,  and 

^  Such  cases  as  these  arc  reported  in  the  admirable  description  of  this  complicated 
aifection  by  my  colleague  and  friend  Professor  W.  A.  Hammond :  "  Treatise  on  the 
Diseases  of  the  Nervous  System."     New  York:  D.  Appleton  &  Co.,  18Y6. 

2  "  Med.  Record,"  1881. 


528 


THE  CRANIAL  NERVES. 


Fig.  154. — A  diagram  of  the  motor  points  of  the  face^  showing  the  position  of  the  electrodes 
dwing  electrisation  of  special  mtiscles  and  nerves,  llie  anode  is  supposed  to  be  placed 
in  the  mastoid  fossa,  and  the  cathode  upon  the  part  indicated  in  the  diagram. 

1,  in.  orbicularis  palpebrarum  ;  2,  m.  pyramidalis  nasi ;  8,  m.  lev.  lab.  sup.  et  nasi ;  4,  m. 
lev.  lab.  sup.  propr. ;  5,  6,  m.  dilator  naris  ;  7,  m.  zygomatic  major ;  8,  m.  orbicularis 
oris;  9,  n.  branch  for  levator  menti ;  10,  m.  levator  nienti ;  11,  m.  quadratus  menti; 
12,  m.  triangularis  menti;  13,  nerves — subcutaneous  of  neck;  14,  m.  stcrno-hyoid ; 
15.  m.  omo-hyoid  ;  16,  m.  sterno-thyroid  ;  17,  n.  branch  for  platysma ;  18,  m.  sterno- 
hyoid ;  19,  m.  omo-hyoid;  20,  21,  nerves  to  pectoral  muscles;  22,  ro.  occipito- 
f rontalis  (ant.  belly) ;  23,  m.  occipito-frontalis  (post,  belly) ;  24,  m.  retrahens  and 
attollens  aurem ;  25,  nerve — facial ;  26,  m.  stylo-liyoid ;  27,  m.  digastric ;  28,  ra. 
splenius  capitis ;  29,  nerve — external  branch  of  spinal  accessory ;  30,  m.  sterno- 
mastoid;  31,  m.  sterno-mastoid ;  32,  m.  levator  anguli  scapulae;  33,  nerve — phrenic; 
34,  nerve — posterior  thoracic ;  35,  m.  serratus  magnus ;  36,  nerves  of  the  axil- 
lary space. 

even  seek  roundabout  ways  of  expressing  their  meaning  by 


shorter    words. 


Besides    this    vibratory   tremulousness    in   n 


SPASM  AND  PARALYSIS  OF  THE  TONGUE.  529 

articulation,  there  is  an  imperfection  in  the  pronunciation 
of  words — long  words  especially.  Remedy  is  pronounced 
'remdy';  constitution,  '  constution ';  infallibility,  'infallaby.' 
The  last  syllable  may  be  badly  sounded,  or  even  omitted.  I 
have  known  this  characteristic  sp'eech  to  be  the  only  well- 
marked  symptom,  and  to  be  followed  by  dementia,  exaltation, 
etc.  Occasionally,  a  patient  comes  to  us  complaining  of  this 
defective  articulation." 

Interference  with  the  free  action  of  the  hypo-glossal  nerve, 
when  not  associated  with  a  simultaneous  affection  of  other 
nerves,  may  result  in  the  production  of  spasm  or  paralysis. 

Spasm  of  the  tongue  may  be  perceived  in  connection  with 
the  spasmodic  diseases,  such  as  chorea,  epilepsy,  and  hys- 
teria ;  also,  as  a  result  of  slight  compression  or  irritation  of 
the  hypoglossal  nerve  from  meningeal  exudation ;  while  a 
fibrillary  tremor  of  the  tongue  is  observed  in  progressive 
muscular  atrophy.  In  severe  types  of  facial  spasm,  and  in 
those  forms  of  disease  where  the  lingual  nerve  is  the  seat  of 
a  neuralgic  affection,  the  hypo-glossal  nerve  may  create  a 
type  of  clonic  spasm. 

Paralysis  of  tJie  tongue  is  usually  unilateral,  and  may 
be  the  result  of  cerebral  haemorrhage,  softening,  embolism, 
tumors,  or  the  progressive  paralysis  of  the  insane.  In  rare 
cases,  this  condition  has  occurred  from  injury  done  to  the 
nerve  from  the  removal  of  a  tumor  of  the  tongue  itself ;  while 
instances  have  been  reported  where  the  nerve  was  impaired 
by  pressure  upon  its  tVunk,  either  at  the  base  of  the  brain,  or 
at  its  point  of  escape  from  the  anterior  condyloid  foramen. 


THE  SPII^AL  CORD. 

ITS   ANATOMICAL   CONSTRUCTION,    FUNCTIONS,    AND 
CLINICAL  BEARINGS. 


m 


THE    AEOHITEOTUEE    OF    THE 
SPI]:^AL    COED. 


The  spinal  cord  comprises  that  part  of  our  central  nerv- 
ous system  which,  is  contained  within  the  canal  of  the  verte- 
bral column.  It  is  continuous  with  the  medulla  oblongata. 
It  may  be  said  to  commence  at  the  point  where  the  fibers 
of  the  anterior  pyramids  of  the  medulla  oblongata  decus- 
sate (which  point  corresponds  to  the  upper  border  of  the 
atlas),  and  to  terminate  at  the  lower  border  of  the  first  lumbar 
vertebra.' 

In  the  foetus,  during  its  development,  and  in  the  new-born 
child,  the  spinal  cord  extends  throughout  nearly  the  entire 
length  of  the  vertebral  canal.  The  vertebral  column  increases 
in  length  with  age,  but  the  cord  does  not  grow  proportion- 
ately ;  hence,  in  the  adult,  it  reaches  only  to  the  body  of  the 
first  or  second  lumbar  vertebra,  and  the  cauda  equina  fills  the 
remaining  part  of  the  spinal  canal. 

The  circumferential  measurement  of  the  spinal  cord  is 
about  one  inch.  At  its  largest  part  this  measurement  is  ex- 
ceeded by  about  two  lines  (one  sixth  of  an  inch). 

The  entire  length  of  the  cord  varies  from  fifteen  to 
eighteen  inches  in  the  adult  (since  it  depends  somewhat  upon 
the  height  of  the  individual).  Its  upper  end  is  not  only  ap- 
parently continuous  with  the  lower  part  of  the  medulla  ob- 

*  Fehst  ("  Cent,  fiir  d.  med.  Wiss.,"  1874)  asserts  that  the  spinal  cord  in  women  reaches 
to  the  lower  level  of  the  second  lumbar  vertebra. 


634 


THE  SPINAL   CORD, 


longata  (which,  in  my  opinion,  seems  more  properly  a  part  of 
the  cord  than  of  the  brain),  but  actually  so,  as  the  fibers  of 
one  extend  into  the  substance  of  the  other.     Its  lower  end 


Fig.  165. —  Cervical  por- 
tion of  the  spinal  cord. 
(Hirschfeld.) 


iiiiSuA-^ 


Fig.  156. — Dorsal  pcyr- 
tion  of  the  spinal  cord. 
(Hirschfeld.) 


S.SALtS    II 

Fig.  157. — Inferior  portion  oi 
the  spinal  cord  and  cauda 
equina.    (Hirschfeld.) 


1,  antero-inferior  wall  of  the  foui-th  ventricle ;  2,  superior  peduncle  of  the  cerebellum ; 
3,  middle  peduncle  of  the  cerebellum  ;  4,  inferior  peduncle  of  the  cerebellum ;  5,  in- 
ferior portion  of  the  posterior  median  columns  of  the  cord ;  6,  glosso-pharyngeal 
nerve ;  7,  pneumogastric ;  8,  spinal  accessory  nerve ;  9,  9,  9,  9,  dentated  ligament ; 
10,  10,  10,  10,  posterior  roots  of  the  spinal  nerves  ;  11, 11, 11,  11,  posterior  lateral 
groove  ;  12,  12,  12,  12,  ganglia  of  the  posterior  roots  of  the  nerves  ;  13,  13,  anterior 
roots  of  the  nerves  ;  14,  division  of  the  nerves  into  two  branches  ;  15,  lower  extremity 
of  the  cord;  16,  16,  coccygeal  ligament;  17,  17,  cauda  equina;  I-VIIT,  cervical 
nei'vcs  ;  I,  II,  III,  IV-XII,  dorsal  nerves  ;  I,  II-V,  lumbar  nerves  ;  I-V,  sacral  nerves. 


terminates  in  a  slender  filament,  called  the  *^filum  termi- 
nale,"  that  descends  for  a  short  distance  into  the  central 
ligament. 

The  three  admirable  cuts  of  Hirschfeld,  which  are  here 
introduced,  illustrate  the  appearance  of  the  adult  spinal  cord 
in  the  cervical,  dorsal,  and  lumbar  regions  after  its  investing 


ADJUSTMENT  WITHIN  SPINAL   CANAL.  535 

membranes  have  been  so  divided  as  to  expose  the  spinal 
nerves  that  escape  from  its  substance.  In  the  cut  illus- 
trating the  cervical  region,  the  fourth  ventricle  of  the  brain 
(which  is  within  the  medulla)  is  exposed  to  view.  The 
dentate  ligament  of  the  cord  (which  is  formed  by  the  pia 
mater  or  its  internal  investing  membrane)  is  also  shown 
in  all  three  cuts.  Some  other  points  in  the  construction 
of  the  cord  and  the  spinal  nerves  are  clearly  depicted,  but 
they  will  be  made  more  apparent  in  subsequent  diagrams. 
Should  any  part  of  the  descriptive  text  of  these  cuts  seem 
incomplete  to  the  reader,  subsequent  portions  of  this  chap- 
ter will  furnish  the  additional  information  that  may  be 
desired. 

Within  the  vertebral  canal  the  spinal  coid  hangs  free,  and 
exhibits  a  considerable  degree  of  mobility.  Except  at  the 
two  upper  cervical  vertebrae  and  in  the  lumbar  region,  the 
cord  is  well  protected  by  the  overlapping  spines  of  the  verte- 
brae from  injuries  sustained  posteriorly.  The  vertebral  canal 
is  lined  throughout  with  a  hard  periosteum,  which  covers  the 
bones. 

The  cord  is  practically  suspended  in  the  cerebro-spinal 
fluid.  This  arrangement  serves  as  a  protection  against  injury 
from  violence  transmitted  by  means  of  the  spinal  column ; 
because,  as  is  well  known,  a  fluid  medium  distributes  force 
applied  to  it  in  all  directions  equally. 

The  consistence  of  the  cord  is  liable  to  variations.  Im- 
mediately after  death  it  is  elastic  and  easy  to  cut,  its  cut 
surface  being  smooth  and  its  edges  well  defined  and  sharp. 
After  death  it  tends  rapidly  to  become  soft,  so  that  sections 
of  the  cord  are  seldom  satisfactory  for  microscopical  exami- 
nation, unless  the  specimen  be  perfectly  fresh  when  removed 
from  the  canal  and  placed  immediately  in  some  preserving 
fluid.  The  cord  and  its  envelopes  come  far  from  filling  the 
entire  canal  of  the  vertebral  column.  This  circumstance 
tends  to  protect  the  cord  from  injury  during  movements  of 
the  spine,  especially  in  the  cervical  and  lumbar  regions,  where 
movement  is  comparatively  free  and  unrestricted. 


536 


THE  SPINAL   CORD, 


THE  EXTERNAL  APPEARANCE  OF  THE  CORD. 

The  spinal  cord  is  not  of  the  same  size  or  shape  in  all  por- 
tions of  its  length.  It  is  nearly  cylindrical  in  form  and  tapers 
gradually  toward  its  lower  extremity,  with  the  exception  of 
presenting  two  local  enlargements,  called  the  ^'cermcaV^  and 
'lumbar ''^  enlargements. 


Fig.  158. — Transverse  section  of  the  cervical  enlargement  of  the  spinal  cord  at  the  origin 
of  the  fifth  pair  of  cervical  nerves.     (Stilling.) 

In  this  figure  the  white  substance  of  the  cord  is  represented  in  black,  to  show  more  clearly 
the  limits  of  the  gray  matter:  1,  1,  antero-lateral  columns  ;  2,  2,  posterior  white  col- 
umns ;  3,  anterior  median  fissure ;  4,  posterior  median  fissure ;  5,  white  commissure ; 
6,  gray  commissure;  7,  central  canal;  8,  9,  anterior  comua  of  gray  matter;  10,  10, 
group  of  large  multipolar  cells;  11,  11,  11,  anterior  roots  of  the  spinal  nerves;  12, 
posterior  comua  of  gray  matter  containing  the  so-called  "  substantia  gelatinosa " ; 
18,  posterior  roots  of  the  spinal  nerves. 


The  former  of  these  extends  from  the  third  cervical  to  the 
first  dorsal  vertebra,  and  is  widest  from  side  to  side.  The  lat- 
ter extends  from  the  lower  part  of  the  eleventh  dorsal  to  the 
lower  border  of  the  twelfth  dorsal  vertebra,  and  is  widest 
from  before  backward.* 

The  shape  of  a  transverse  section  of  the  cord  varies  with 
the  level  at  which  the  section  is  made. 

In  the  dorsal  region,  it  is  nearly  circular.     In  the  cervical 


'  These  enlargements  correspond  to  the  points  of  origin  of  the  main  nerves  of  the 
upper  and  lower  extremities.  They  indicate,  therefore,  an  excess  of  the  ganglionic-cell 
elements  over  those  found  in  the  dorsal  region. 


FISSURES  OF  THE  CORD.  537 

and  lumbar  enlargements,  the  transverse  diameter  of  the  sec- 
tion is  broadened  and  the  whole  section  assumes  an  approach 
to  the  triangular  form,  the  base  of  which  is  directed  forward. 
Finally,  the  cord  assumes  the  form  of  a  half -moon  in  the  low- 
est segments,  with  its  convexity  directed  backward. 

When  viewed  exteriorly,  the  cord  presents  five  fissures 
and  four  pairs  of  vertical  columns,  which  are  less  distinct 
than  the  convolutions  of  the  cerebrum. 

On  a  section  being  made  transversely  across  its  substance, 
two  general  subdivisions  can  be  discerned  by  the  naked  eye, 
the  white  and  the  gray  portions. 

The  general  exterior  of  the  spinal  cord  is  incompletely 
divided  into  two  symmetrical  lateral  halves^  by  the  so-called 
" antero-median  fissure"  and  the  " postero-median  fissure." 
These  do  not  cut  the  cord  entirely  in  two,  since  a  transverse 
commissure  exists,  called  the  ''''commissure  of  tJie  spinal 
cordy  Now,  this  point  is  worthy  of  attention,  because  it  in- 
dicates a  clinical  fact,  viz.,  that  lesions  of  one  lateral  half  of 
the  cord  produce  symptoms  in  a  lateral  half  of  the  body. 

Each  lateral  half  of  the  cord  has  three  fissures  of  its 
own : 

1.  The  '^antero-lateral  fissure."  This  corresponds  to  the 
points  of  escape  of  the  anterior  roots  of  the  spinal  nerves. 

2.  The  " postero-lateral  fissure."  This  corresponds  to  the 
points  of  attachment  to  the  posterior  roots  of  the  spinal 
nerves. 

3.  The  ^'postero-intermediary  fissure."'  This  is  situated 
between  the  postero-median  fissure  (which  helps  to  divide 
the  cord  into  its  two  lateral  halves)  and  the  postero-lateral 
fissure. 

The  first  two  of  these  are  mere  traces  upon  the  surface 
of  the  cord,  while  the  last  is  most  apparent  in  the  cervical 
region. 

^  The  postero-intermediary  fissure  extends  from  the  lower  border  of  the  medulla  to 
the  lower  end  of  the  cervical  enlargement  of  the  spinal  cord.  It  is  not  associated  with 
the  transit  of  nerve  roots,  in  which  respect  it  differs  from  the  antero-lateral  and  postero- 
lateral fissures. 


538 


THE  SPINAL   CORD. 


As  demarkated  by  the  fissures  named  above,  the  spinal 
cord  presents  four  subdivisions  of  its  exterior  surface,  called, 
respectively,  the  '^anterior,"  '^ lateral,"  ''postero-external," 
and  "  postero- median  "  columns. ' 


Fig.  159. —  Tra^isverse  section  of  the  spinal  cord  of  a  child  six  months  old,  at  the  middle  of 
the  lumbar  enlargement,  treated  loith  potassio-chloride  of  gold  and  nitrate  of  uranium  ; 
magnified  20  diameters.  By'  means  of  tJiese  reagents  the  direction  of  the  fibers  in  the 
gray  substance  is  rendered  unuxuaUy  distinct.     (Gerlach.) 

a,  anterior  columns ;  6,  posterior  columns ;  c,  lateral  columns ;  d,  anterior  roots  ;  c,  poste- 
rior roots ;  /,  anterior  white  commissure,  in  connection  with  the  fasciculi  of  the  an- 
terior cornua  and  the  anterior  columns ;  g,  central  canal  with  its  epithelium ;  h,  sur- 
rounding connective  substance  of  the  central  canal ;  i,  transverse  fasciculi  of  the  gray 
commissure  in  front  of  the  central  canal ;  k,  transverse  fasciculi  of  the  gray  commis- 
sure behind  the  central  canal ;  l,  transverse  section  of  the  two  central  veins ;  m,  ante- 
rior cornua ;  n,  great  lateral  cellular  layer  of  the  anterior  cornua ;  o,  lesser  anterior 
cellular  layer ;  p,  smallest  median  cellular  layer ;  q,  posterior  cornua ;  r,  ascending 
fasciculi  in  the  posterior  cornua ;  s,  substantia  gclatinosa. 


These  are,  however,  of  less  importance,  from  a  clinical 
standpoint,  than  those  columns  of  fibers  named  after  certain 
special  investigators  in  this  line  of  science,  or  from  their 

'  Some  anatomists  include  the  lateral  with  the  anterior  column,  under  the  name  of 
"  the  antero-lateral  column,"  thus  taking  in  about  two  thirds  of  the  entire  lateral  half  of 
the  cord. 


MEMBRANES  OF  THE  CORD.  539 

physiological  functions.  Subsequent  diagrammatic  cuts  of 
the  subdivisions  now  accepted  as  definitely  localized  in  all 
transverse  sections  of  the  spinal  cord  illustrate  them. 

When  we  come  to  discuss  the  clinical  points  pertaining  to 
spinal  localization,  in  case  of  disease,  you  will  realize  that 
the  further  subdivisions  of  the  spinal  cord,  which  I  shall  en- 
deavor to  impress  upon  your  memories,  are  not  based  alone 
upon  the  results  of  enthusiastic  microscopy,  but  are  the  evi- 
dences of  progress  in  this  direction  which  the  earlier  anato- 
mists had  not  dreamed  of,  and  the  foundation  of  all  accurate 
and  positive  diagnosis  of  certain  varieties  of  spinal  lesions. 

The  spinal  cord  gives  off  thirty -one  pairs  of  nerves^  called 
"spinal  nerves,"  in  contradistinction  to  those  of  cranial 
origin. 

Each  spinal  nerve  arises  by  two  roots,  which  spring,  re- 
spectively, from  two  of  the  fissures  of  the  lateral  halves  of 
the  cord,  as  has  been  mentioned.  These  two  roots  join  each 
other  to  form  the  nerve  before  it  escapes  from  the  spinal 
canal  to  be  distributed  to  the  regions  which  it  is  destined  to 
supply. 

Each  pair  of  nerves  and  the  disk  of  the  cord  to  which  they 
are  attached  constitute  what  is  known  as  a  "spinal  segment. ^^ 

THE   MEMBRANES   OF  THE   SPIN^AL   CORD. 

As  was  the  case  with  the  encephalon,  the  spinal  cord  is 
invested  from  within  outward  by  a  membrane  of  nutrition, 
the  pia  mater ;  a  membrane  of  lubrication,  the  arachnoid ; 
and,  finally,  a  membrane  of  protection,  the  dura  mater. 

These  three  coverings  differ  slightly  in  some  respects  from 
those  covering  the  brain,  but  the  differences  have  little  if 
anything  to  do  with  the  clinical  aspects  of  the  spinal  cord. 

The  DUEA  MATER  of  the  cord  is  a  cylindrical  sac  of  fibrous 
tissue  of  larger  dimensions  than  the  cord.  It  is  closely  at- 
tached above  to  the  foramen  magnum  of  the  occipital  bone, 
and  ends  below  by  becoming  blended  with  the  periosteum  of 
the  coccyx.  Its  outer  surface  is  invested  by  a  layer  of  fat 
which  separates  it  from  the  bones.     As  the  spinal  nerves  per- 


640 


THE  SPINAL   CORD. 


forate  it,  the  dura  and  neurilemma  become  blended.  The 
vertebral,  intercostal,  and  lumbar  arteries  furnish  it  with 
blood.  Large  plexuses  of  veins  are  found  on  the  anterior 
and  posterior  portions  of  the  dura.  These  connect  with  the 
external  vertebral  plexuses. 

The  PiA  MATER  envelops  the  cord,  like  a  tight-fitting 
glove,  from  top  to  bottom.  It  sends  processes  into  the  sub- 
stance of  the  cord,  which  subdivide  and  form  a  framework 
for  the  nervous  elements  that  compose  it.  It  is  also  joined  to 
the  dura  by  from  twenty  to  twenty-three  processes  upon  each 
side,  called  the  ^'Ugamenta  denticulata?''  These  serve  to 
retain  the  cord  in  its  proper  relations  to  the  vertebral  canal. 
The  pia  mater  is  rich  in  blood-vessels  and  nerves,  and  owes  its 
toughness  to  a  network  of  wavy  connective-tissue  fibers.  Its 
nerves  come  from  the  posterior  roots  of  the  spinal  nerves. 
In  old  subjects,  the  pia  is  often  markedly  pigmented  in  the 
cervical  region. 


1, 


Fig.  160. — This  diagram  has  been  introduced  to  show  the  arrangement  of  the  different  mem- 
branes and  spaces  as  they  are  believed  to  exist  in  the  spinal  column.     (After  Hilton.) 

,  dura  mater  passing  down  to  end  on  the  sheath  of  the  nerves ;  2,  2,  layers  of  arach- 
noid forming ;  3,  cavity  of  arachnoid ;  4, 4,  pia  mater  ending  on  nerve-sheath  ;  5,  5, 
ligamentum  denticulatum ;  6,  gray  matter  of  spinal  cord  ;  7,  delicate  areola  tissue 
found  in  the  sub-arachnoid  space  between  the  arachnoid  and  pia  mater ;  8,  anterior 
and  smaller,  9,  posterior  and  larger,  roots  of  spinal  nerve ;  10, 10,  similar  tissue  to  7. 


The  ARACHNOID,  like  all  serous  membranes,  consists  of  a 
closed  sac  with  a  cavity  between  its  two  layers.  The  inner 
layer  becomes  blended  with  the  pia  mater  as  that  membrane 
is  prolonged  upon  the  spinal  nerve  roots  (Fig.  160).     Between 


iti 


THE  CEREBROSPINAL  FLUID.  541 

the  pia  mater  and  the  arachnoid  there  exists  a  loose  areolar 
tissue,  known  as  the  "  suh-arac7inoidean  tissue,^'^  which  con- 
tains a  fluid  called  the  cerebro-spinal  fluid. 

THE   CEREBRO-SPINAL   FLUID. 

As  mentioned  in  connection  with  the  ventricular  cavities 
of  the  brain,  the  spinal  cord  is  immersed,  as  it  were,  in  a 
fluid,  the  '-'  cerebro-spinal  Jluid^'^^  which  has  free  entrance  to 
and  egress  from  the  ventricles  of  the  encephalon.     Its  chief 
function  is  to  regulate  and  equalize  the  pressure '  upon  the 
nerve  centers,  when  the  blood- supply  suffers  variations,  as  it 
does  during  respiration,  in  sleep,  and  in  certain  diseased  con- 
ditions.    This  accounts  for  the  fact  that  pressure  made  upon 
ia  ^' spina  bifida" — a  tumor  containing  this  fluid  protruding 
'■  through  an  opening    due  to  a  congenital   absence  of    the 
spinous  processes  of  the  vertebrae — often  creates  brain  symp- 
toms, if  sufficient  to  create  excessive  intra-ventricular  pressure. 
The  greater  part  of  this  fluid  is  contained  in  what  is 
kaown  as  the  sub-aracJinoidean  space,  which  is   situated 
outside  of  the  cavity  of  the  arachnoid,  between  its  inner 
layer  and  the  pia  mater  of  the  cord.     Its  quantity  was  esti- 
mated by  Magendie  as  about  two  fluid  ounces  in  the  human 
subject ;  but  a  somewhat  larger  amount  can  be  obtained  by 
j  making  an  opening  in  the  lumbar  region  and  a  counter-open- 
;  ing  in  the  region  of  the  head,  so  as  to  allow  of  the  influence 
!  of  atmospheric  pressure  in  forcing  its  escape  outward. 

This  fluid  may  be  drawn  out  of  the  spinal  canal  of  a  living 
animal,  either  by  means  of  a  simple  trocar  or  a  trocar  at- 
tached to  a  suction- tube.  In  the  former  method  no  apparent 
i  influence  of  a  detrimental  character  seems  to  follow  a  mod- 
erate escape  ;  but,  when  a  suction  force  is  used  to  still  further 
draw  off  the  fluid,  the  animal  becomes  enfeebled  and  subse- 
quently affected  with  symptoms  of  motor  paralysis.  The 
I  cerebro-spinal  fluid  is  rapidly  reproduced  after  its  withdrawal, 
and  is  probably  secreted  by  the  pia  mater. 

'  Hilton  considers  this  fluid  as  analogous,  in  respect  to  its  function,  to  the  clastic 
,   capsule  of  the  various  solid  viscera.     "  Rest  and  Pain,"  London,  1876. 

i  37 


542  THE  SPINAL   CORD. 

The  fact  that  an  increase  of  the  intra-cerebral  x>ressure 
will  result  in  coma,  if  sufficiently  intensified,  is  shown,  in  a 
clinical  way,  upon  the  human  subject,  by  compression  of  a 
spina  bifida  ;  and  the  same  result  was  proved  by  Magendie, 
who  injected  water  into  the  sub-arachnoidean  space  of  ani- 
mals, and  thus  artificially  induced  a  state  of  profound  coma. 
The  point  of  communication  between  the  sub-arachnoidean 
space  of  the  spinal  canal  and  the  ventricular  cavities  of  the 
brain  is  situated  in  the  fourth  ventricle  ^'"^  hence,  the  fluid 
has  to  pass  upward,  through  the  aqueduct  of  Sylvius,  to  j| 
reach  the  third  ventricle,  and  through  the  foramina  of  Monro, 
to  enter  the  two  lateral  ventricles  of  the  cerebrum.     Hilton "  ] 
maintains  that  the  basilar  process  of  the  occipital  bone  (which 
is  in  close  relation  to  that  part  of  the  encephalon  which  is 
most  essential  to  life)  is  not  in  actual  contact  with  the  adja- 
cent bone,  but  has  a  layer  of  the  cerebro- spinal  fluid  inter- 
posed as  a  water-bed  to  protect  the  parts  from  injury  from  j 
any  form  of  concussion.     A  similar  condition  exists  also  in 
other  parts."    The  cerebro-spinal  fluid  is  never  in  a  state  ofl 
repose.     The  influence  of  respiration  affects  it,  by  causing  a : 
decrease  in  the  arterial  pressure  in  the  brain  during  inspira- 
tion and  an  increase  during  expiration.     A  a  result  of  the 
variations  in  the  volume  of  blood  within  the  cavity  of  the! 
skull,  the  cerebro-spinal  fluid  rises  and  falls  in  quantities 
sufficient  to  maintain  an  equal  pressure  upon  the  brain  sub- 
stance.    It  seems  to  be  proved  that  the  cerebro-spinal  fluid 
is  constantly  secreted  by  the  pia  mater,  and  as  constantly 
carried  off  by  the  lymphatic  channels. 

Hyrtl  has  suggested  that  the  displacement  of  the  cerebro- 
spinal fluid  is  facilitated  to  a  marked  degree  by  the  emptying 
and  filling  of  the  veins  of  the  spinal  canal.  He  believes  that 
the  spinal  veins  are  overfilled  and  distended  during  inspira- 
tion by  the  descent  of  the  diaphragm,  because  pressure  is 
then  exerted  upon  the  abdominal  viscera  by  that  muscle. 

'  The  foramen  of  Magendie.  '^  Op.  cit. 

'  The  reader  is  referred  to  those  pages  in  the  section  upon  the  brain  that  treat  of  the 
arachnoid  and  pia  mater. 


BLOOD-VESSELS  OF  THE  CORD.  543 

This  tends  to  impede  the  flow  of  blood  into  the  lumbar  veins. 
The  opposite  effect,  however,  is  produced  at  this  time  upon 
the  cerebral  sinuses,  as  they  are  emptied  by  the  tendency  to 
a  vacuum  created  within  the  chest  when  the  diaphragm  be- 
comes lowered.  The  return  of  the  abdominal  viscera,  which 
follows  the  diaphragm  when  it  relaxes  (e.  g.,  during  expira- 
tion), assists  in  emptying  the  spinal  veins ;  but  at  the  same 
time  it  creates  engorgement  of  the  veins  of  the  head  and  neck 
by  interfering  with  the  entrance  of  blood  into  the  thorax. 
Thus  it  appears  that  the  cerebro- spinal  fluid  is  forced  out 
of  the  ventricles  of  the  brain  during  expiration  by  the  ex- 
cess of  blood  in  the  veins  of  that  organ,  and  that  the  spinal 
veins  are  then  empty,  in  order,  as  it  were,  to  make  room 
for  the  excess  of  the  spinal  fluid  which  is  displaced  by  the 
cerebral  engorgement.  During  inspiration,  the  direction  of 
the  displacement  is  reversed. 

THE   BLOOD-VESSELS   OF  THE   CORD. 

The  tissue  of  the  spinal  cord  is  peculiarly  rich  in  blood- 
vessels. The  arteries  enter  from  the  pia  mater  and  accom- 
pany the  processes  which  that  membrane  sends  into  the  sub- 
stance of  the  cord.  They  subdivide  after  entering  the  cord 
and  form  a  network  of  capillaries  both  in  the  gray  and  white 
substance.  The  vertebral  arteries  give  off  branches  that  form 
the  anterior  and  posterior  spinal  arteries.  These  run  continu- 
ously from  the  foramen,  magnum  to  the  conus  terminalis. 
The  intercostal  and  lumbar  arteries  anastomose  freely  with 
the  anterior  and  posterior  spinal  vessels  ;  hence  counter-irri- 
tation over  the  spines  of  the  vertehrce  causes  a  direct  effect 
upon  the  vascular  supply  of  the  cord  itself  as  well  as  upon 
the  meninges. 

The  intercostal  and  lumbar  arteries  enter  the  vertebral 
canal,  by  means  of  the  intervertebral  foramina,  in  company 
with  the  nerve  roots. 

The  capillaries  of  the  cord  empty  into  two  venous  trunks 
that  run  in  the  gray  commissure  of  the  cord  on  either  side 
of  the  central  canal  for  its  entire  length,  and  also  into  a 


544  TEE  SPINAL   CORD, 

large  vein  that  accompanies  the  anterior  spinal  artery  for  the 
entire  length  of  the  cord,  lying  in  the  anterior  median  fissure. 
In  the  posterior  median  fissure  a  similar  vein  may  be  traced 
for  the  entire  length  of  the  cord.  The  veins  within  the  spinal 
gray  matter  anastomose  with  the  external  veins  already  de- 
scribed by  horizontal  branches ;  and  these,  again,  join  with 
each  other,  and  also  with  the  large  venous  plexuses  that  lie 
in  the  fatty  tissue  outside  of  the  dura  and  with  the  external 
vertebral  veins. 

THE  VERTEBRA   AS   GUIDES  TO   THE  SPINAL  SEGMENTS. 

By  sharp  friction  over  the  spinal  column,  the  tips  of  the 
spinous  processes  can  be  made  very  apparent  as  well-defined 
red  spots.     They  can  then  be  readily  counted. 

It  is  desirable  often  to  know  what  part  of  the  vertebral 
column  corresponds  to  the  level  of  origin  of  each  pair  of  spi- 
nal nerves.  The  spines  of  the  vertebrae  can  be  felt  even  in  fat 
subjects,  and  thus  guides  may  be  had  in  each  individual  to 
locate  the  levels  of  the  various  spinal  segments.  To  do  this 
with  accuracy,  however,  is  rendered  somewhat  difiicult  (1)  by 
the  fact  that  the  spinal  nerves  do  not  escape  from  the  fo- 
ramina between  the  pedicles  of  the  vertebrae  at  the  same  level 
at  which  they  arise  from  the  spinal  cord  ;  and  (2)  because  the 
tips  of  the  spinous  processes  do  not  correspond  to  the  bodies 
of  the  corresponding  vertebrae  in  all  parts  of  the  spinal  col- 
nmn. 

The  spinal  nerves  escape  from  the  cervical  foramina  nearly 
on  a  level  with  their  origin  from  the  cord,  but  the  obliquity 
of  the  nerves  increases  steadily  in  the  dorsal  and  lumbar 
regions,  so  that  the  lowest  nerves  that  constitute  the  cauda 
equina  have  a  very  long  course  before  they  escape  from  the 
foramina  of  the  lumbar  region  and  the  sacrum. 

Gowers  gives  the  following  deductions  as  aids  to  deter- 
mine the  situation  of  the  bodies  of  the  vertehi^ce  during  life : 
"  The  tips  of  the  cervical  spines  correspond  nearly  to  the 
lower  borders  of  the  corresponding  vertebrae.  Each  of  the 
three  upper  dorsal  spines  corresponds  nearly  to  the  upper 


GUIDES  TO   THE  SPINAL  SEGMENTS.  545 

border  of  the  body  of  the  vertebra  below.  From  the  fourth 
to  the  eighth  dorsal,  each  spine  corresponds  to  the  middle  of 
the  vertebra  below.  The  ninth,  tenth,  and  eleventh  spines 
slope  less,  and  their  tips  again  correspond  to  the  upper  bor- 
ders of  the  next  vertebrae,  while  the  rest  of  the  spines  are 
opposite  the  bodies  of  their  own  vertebrae."  Fig.  161  will 
make  these  statements  apparent. 

With  these  guides  to  the  bodies  of  the  vertebrae,  it  now 
becomes  necessary  to  consider  the  relations  of  the  spines  to 
the  origins  of  the  spinal  nerves.  In  the  cervical  region,  the 
first  three  spines  correspond  to  the  origins  of  the  third, 
fourth,  and  fifth  cervical  nerves  ;  the  sixth  cervical  spine  cor- 
responds to  the  origin  of  the  eighth  cervical  nerve,  and  the 
intervals  between  the  fourth  and  fifth  spines,  and  the  fifth 
and  sixth,  correspond  to  the  origins  of  the  sixth  and  seventh 
cervical  nerves  respectively. 

In  the  dorsal  region,  the  seventh  cervical  spine  usually 
corresponds  to  the  origin  of  the  first  dorsal  nerve ;  the  first 
dorsal  spine  to  the  third  dorsal  nerve ;  the  second  spine  to 
the  fourth  nerve ;  the  third  spine  to  the  fifth  nerve ;  the 
fourth  spine  to  the  sixth  nerve  ;  and  so  on  down  to  the  tenth 
spine,  which  lies  opposite  the  twelfth  nerve.  It  may,  there- 
fore, be  given  as  a  rule  that  the  dorsal  spines  lie  opposite  the 
level  of  the  origin  of  the  nerve  that  escapes  from  the  spinal 
canal  two  vertebrce  lower  down. 

The  lumbar  and  sacral  nerves  all  arise  within  a  space  that 
corresponds  to  the  interval  between  the  eleventh  dorsal  spine 
and  the  first  lumbar  spine.  The  course  of  each  nerve  within 
the  spinal  canal  from  the  first  lumbar  to  the  coccygeal  nerves, 
therefore,  becomes  longer  than  the  preceding  ones  as  they  are 
given  off  from  the  cord. 

The  excellent  cut  devised  by  Gowers,  which  is  here  intro- 
duced, will  enable  the  reader  to  more  easily  follow  the  pre- 
ceding text.  It  shows  in  a  diagrammatic  way  the  varying 
relations  between  the  bodies  of  the  vertebrae,  the  origins  of 
spinal  nerves,  and  the  tips  of  the  vertebral  spines.  It  must 
be  always  remembered  that  the  spinal  nerves  are  named  from 


546 


THE  SPINAL    CORD. 


MOTOR. 


St.-mastoid 
Trapezius 

Diaphragm 

(Serratus 
Shoulder  "j 

Ann  j-mr 

Hand        J 
(ulnar  lowest) 


^Intercostal 
Muscles. 


Abdominal 
Muscles. 


Flexors,  hip 
Extensors,  knee 


Abductors 


Adductors 


SENSORY. 

Neck  and  scalp 
Neck  and  shoulder 

Shoulder 

Arm 

Hand 


HEFLEX. 


Scapular 


■  Front  of  thorax 
Ensif  orm  area 


Abdomen 
(Umbilicus  10th) 


(Buttock,  upper 
part 

Groin  and  scrotum  •  1 
(front)  I 

outer  side 


Epigastric 


Abdominal 


Thigh 


^  Cremasteric 


■  front 


!1 


hip 


Exten8or8(?) 
Flexors,  knee  (?) 

Muscles    of     leg 
moving  foot 


I  Perineal   and  Anal  (.Perinseumand 


f    Muscles 


t  inner  side     ] 
Leg,  inner  side 
iuttock,  lower 
part 


Gluteal 


Back  of  thigh        J 
lanS  t.  except         Foot-clonus 

f"ooti^^««'-P*'-t       „,     , 
Plantar 


Anus 


Skin  from  coccyx 
to  anus 


Fig.  161. — A  diagram  designed  to  sJiow  the  relations  of  the  vertebrfs  to  the  spinal  segments, 
and  of  the  spinal  nerves  to  the  moior^  sensory^  and  reflex  functions  of  the  spinal  cord. 
(Gowers.) 


HISTOLOGICAL  ELEMENTS   OF  THE  CORD.  547 

the  situation  of  the  foramen  through  which  they  escape 
from  the  canal  of  the  vertebral  column ;  and  that  the  name 
of  the  nerve  must  never  be  construed  as  indicating  the  level 
of  its  point  of  origin.  Thus,  for  example,  the  sacral  nerves 
escape  into  the  cavity  of  the  pelvis,  but  they  arise  in  the 
lumbar  region.  If  we  seek  to  locate  spinal  lesions  that 
tend  to  create  symptoms  referable  to  special  nerves,  we 
must  first  know  the  level  of  origin  of  the  nerves  that  ex- 
hibit evidences  of  impairment,  as  a  result  of  the  spinal 
lesion.  The  cut  of  Gowers  (Fig.  161)  will  also  make  the 
distribution  of  the  spinal  nerves  apparent. 

THE   HISTOLOGICAL  ELEMENTS   OF  THE   CORD. 

The  nerve  fibers,  nerve  cells,  and  connective  tissue  of  the 
cord  have  been  already  referred  to  in  a  general  way,  but  a  few 
histological  statements  respecting  them  will  not  be  out  of  place. 

The  Nekve  Fibers.— Schwann's  sheath  has  not  yet  been 
satisfactorily  demonstrated  as  investing  any  of  the  fibers  of 
the  cord,  and  it  may  be  said  that,  as  far  as  our  present  knowl- 
edge goes,  all  are  destitute  of  it.  Both  meduUated  and  non- 
medallated  fibers  exist  in  the  cord.  The  former  are  found  in 
great  abundance  in  the  white  substance  and  the  white  com- 
missure, and  also  in  the  gray  matter ;  the  latter  are  not  de- 
tected in  the  white  matter  or  the  white  commissure.  The 
medullated  fibers  vary  in  size.  In  the  anterior  columns  they 
are  very  large ;  in  the  columns  of  Goll  they  are  smaller ;  in 
the  gray  matter  they  are  still  finer.  The  axis-cylinder,  as 
well  as  the  medullary  sheath  of  the  fiber,  may  be  discerned  in 
cross- sections  of  all. 

The  non- medullary  fibers  of  the  cord  appear  as  naked 
axis- cylinders,  without  any  medullary  sheath.  They  exist 
only  in  the  gray  substance,  and  form  a  fine  and  close  network 
of  fibers,  in  which  ganglion  cells  are  imbedded.  The  fine 
medullated  fibers  of  the  gray  matter  form,  however,  the  pre- 
ponderant element. 

In  the  so  called  white  substance  of  the  cord  three  general 
varieties  of  fibers  may  be  demonstrated  : 


548  THE  SPINAL   COED. 

1.  The  longitudinal  strands  or  bundles,  which  constitute 
the  bulk  of  the  conducting  tracts  to  and  from  the  brain  or 
between  the  different  spinal  segments. 

2.  The  oblique  fibers^  that  are  interlaced  with  those  of  the 
preceding  set,  and  are  relatively  few  in  number.  These  are 
probably  fibers  of  termination  of  the  posterior  nerve  roots. 
The  column  of  Burdach  is  traversed  by  many  of  the  bundles 
of  fibers  derived  from  the  posterior  nerve  roots. 

3.  The  horizontal  fibers,  that  are  chiefly  detected  in  the 
white  commissure  and  in  the  region  of  the  anterior  nerve 
roots. 

It  will  aid  us  in  our  review  of  this  subject  to  consider  the 
fibers  of  the  two  spinal  nerve  roots  separately. 

The  FIBER8  OF  THE  ANTERIOR  NERVE  ROOTS,  as  independ- 
ently discovered  by  Sir  Charles  Bell  and  Magendie,  comprise 
all  the  motor  fibers  that  emanate  from  the  cord.  Experi- 
mental, clinical,  and  pathological  investigation  to  date  have 
failed  to  disprove  or  modify  this  statement.  It  is  not  now 
believed  that  any  sensory  fibers  exist  in  the  anterior  spinal 
nerve  roots. 

The  motor  fibers  of  the  cord  appear  to  rise  directly,  for 
the  most  part,  from  the  axis-cylinder  processes  of  the  large 
spinal  cells,  found  in  the  anterior  horns  of  the  gray  matter. 
They  may  be  traced  in  all  cross- sections  of  the  cord  as  dis- 
tinct bundles  which  traverse  the  anterior  root  zones  (Fig.  158). 
They  are  functionally  related  to  the  fibers  that  descend  from 
the  brain  in  the  columns  of  Tiirck,  and  the  crossed  pyrami- 
dal columns  (Fig.  60),  the  spinal  cells  being  a  means  of  com- 
munication between  these  fibers  and  those  of  the  anterior 
roots.  A  few  of  the  fibers  of  the  anterior  roots  can  appar- 
ently be  traced  through  the  white  commissure  of  the  cord 
to  the  opposite  side;  others  appear  to  radiate  through  the 
spinal  gray  matter,  ascending,  descending,  and  passing  in  an 
antero-posterior  direction  ;  finally,  the  majority  join  the  cells 
of  the  anterior  horns  of  the  side  from  which  they  escape. 

The  FIBERS  OF  THE  POSTERIOR  NERVE  ROOTS  are  physio- 
logically  connected  with  the  transmission  of  sensations  of 


FIBEES  OF  TEE  SPIXAL  NERVE  ROOTS.  549 

various  kinds.  The  sheath  which  invests  each  posterior  root 
ceases  at  its  entrance  into  the  cord,  and  its  component  fibers 
at  once  diverge,  some  passing  into  the  posterior  gray  horn 
and  some  entering  the  column  of  Burdach.  We  are  thus 
forced  to  trace  two  distinct  bundles,  whose  fibers  take  various 
directions. 

The  fibers  that  enter  the  posterior  gray  horn  may  be 
traced  as  follows :  (1)  Some  directly  to  the  cells  of  the  pos- 
terior gray  horn ;  (2)  some  to  the  network  of  fibers  which 
form  the  so-called  ''gelatinous  substance"  of  the  horn;  (3) 
some  to  the  anterior  gray  horn  of  the  opposite  side,  by  means 
of  the  gray  commissure  of  the  cord  ;  (4)  some  to  the  opposite 
posterior  gray  horn ;  (5)  Clarke  and  Kolliker  have  shown 
that  a  large  proportion  of  these  fibers  pass  upward  for  a 
greater  or  less  distance  in  the  so-called  ''ascending  bundle  of 
Deiters"  or  "longitudinal  bundle  of  Kolliker,"  when  they 
again  take  a  horizontal  direction  and  join  the  cells  of  the 
posterior  gray  horn  of  the  same  side. 

Those  fibers  that  diverge  into  the  column  of  Burdach, 
when  the  posterior  nerve  root  enters  the  substance  of 
the  cord,  may  be  traced  as  a  descending  and  ascending 
bundle. 

Schultze  has  shown  that  a  bundle  of  small  size  immedi- 
ately descends  for  two  or  three  centimetres  into  the  substance 
of  the  cord,  and  then  passes  into  the  posterior  gray  horn  of 
the  same  side.  A  bundle  of  much  larger  size  seems  to  take 
an  upward  turn,  immediately  after  its  entrance  into  the  cord, 
and  to  give  oif  slips  to  the  posterior  gray  horn  of  the  same 
side  at  different  levels.  The  ultimate  termination  of  these 
slips  appears  not  to  be  uniform  at  different  levels,  as  shown 
in  cross-sections  of  the  cord.  Some  appear  to  cross  by  the 
posterior  gray  commissure  to  the  opposite  side ;  others,  again, 
become  intermingled  with  the  fibers  of  Gerlach's  network  of 
fibers  ;  some  probably  join  the  cells  of  Clark's  column  ;  some 
end  in  the  cells  of  the  corresponding  posterior  gray  horn ; 
some  join  the  cell  groups  in  the  posterior  and  lateral  part  of 
the  anterior  gray  horn  of  the  same  side ;  finally,  some  seem 


550  .  THE  SPINAL   CORD. 

to  pass  forward  into  the  anterior  gray  horn  itself  and  to  be- 
come lost. 

The  posterior  and  anterior  nerve  roots  are  thus  probably 
associated  with  successive  segments  of  the  spinal  gray  matter. 
The  limits  of  the  association  of  the  posterior  roots  appear  to 
be  from  three  centimetres  below  their  point  of  entrance  to 
eight  centimetres  above  it  (Schultze).  It  is  probable  that  all 
the  sensory  fibers  except  those  connected  with  the  muscular 
sense  decussate  within  the  substance  of  the  cord,  either  di- 
rectly or  by  means  of  decussating  cell-processes.  It  has  been 
pointed  out  by  Kobner  that  the  fibers  which  convey  the  sen- 
sations of  temperature  and  pain  decussate  at  a  lower  level, 
after  their  entrance  into  the  cord,  than  do  those  that  convey 
tactile  sensations. 

The  Spinal  Cells. — These  are  the  most  striking  feature 
of  the  gray  matter.  They  vary  (1)  in  size,  according  to  their 
situation,  and  (2)  in  the  presence  or  absence  of  the  peculiar 
process  known  as  the  "axis-cylinder  process,"  which  differs 
from  the  others  in  being  unbranched,  and  in  tending  to  in- 
crease in  size  as  it  departs  from  the  body  of  the  cell.  They 
have  no  cell-membrane ;  their  nucleus  is  large ;  a  glistening 
nucleolus  exists  ;  and  pigment  granules  are  usually  present 
in  abundance  in  the  protoplasmic  mass.  Some  cells,  that  are 
destitute  of  the  so-called  "axis-cylinder  process,"  unite  with 
the  nerve  fibers,  according  to  Gerlach,  by  means  of  a  fine  net- 
work of  nerves. 

The  cells  of  the  anterior  horns  are  the  largest,  and  have 
many  processes ;  those  of  the  vesicular  column  of  Clarke  are 
next  in  point  of  size,  and  nearly  round  ;  and  those  of  the  pos- 
terior horns  are  the  smallest,  and  are  spindle-shaped.  The 
well-defined  groups,  which  are  characteristic  of  the  anterior 
horns,  are  not  found  in  the  posterior  horns.  Some  attractive 
theories  have  been  advanced  respecting  the  individual  func- 
tions of  the  various  forms  of  cells  found  within  the  cord.  The 
motor  function  of  the  large  cells  of  the  anterior  horns  seems 
to  be  w^ell  established ;  but  that  a  special  form  of  cell  may  be 
positively  designated  as  sensory,  another  as  vaso-motor,  and 


II 


SPmAL    CELLS  AND   THE  NEUROGLLA.  551 

a  third  as  trophic  in  function,  seems  as  yet  improbable  and 
visionary. 

A  middle  horn  of  gray  matter  is  described  by  some  au- 
thors as  arising  from  the  external  portion  of  the  gray  mass 
between  the  two  horns  commonly  described.  It  is  also  called 
the  "intermediary  lateral  tract."  In  close  relation  to  this 
tract  the  reticular  processes  (process  of  Lenhossek)  is  dis- 
cerned. It  consists  of  a  matrix  of  neuroglia  and  an  interrupt- 
ing network  of  fibers. 

Ross  describes  a  collection  of  cells  in  the  cervical  region 
that  develop  their  processes  after  birth  (in  which  respect  they 
differ  from  other  groups)  and  which  are  of  large  size.  He 
draws  the  inference,  from  their  situation  and  late  develop- 
ment, that  they  are  chiefly  concerned  in  the  complex  move- 
ments of  the  hand  and  fingers,  or  of  the  corresponding  fore- 
limbs  of  animals. 

The  gray  matter  of  the  cord  differs  from  that  of  the  brain 
in  respect  to  its  distribution,  since  it  is  confined  exclusively 
to  its  central  portion.  In  the  brain  the  larger  proportion  of 
gray  matter  is  distributed  upon  its  exterior  (cerebral  and  cere- 
bellar cortex). 

The  Neuroglia. — A  basement  substance  of  connective- 
tissue  elements  is  found  within  the  cord,  in  the  meshes  of 
which  the  nerve  cells,  the  nerve  fibers,  and  the  vessels  are 
enveloped.  It  serves  to  give  support  to  these  structures  and 
firmness  to  the  cord  as  a  whole.  It  springs  from  the  pia 
mater,  by  numerous  septa  that  enter  the  cord  and  form 
channels  for  the  blood-vessels.  These  septa  divide  and  sub- 
divide to  form  the  delicate  network  in  which  the  nervous  ele- 
ments are  imbedded.  The  researches  of  Boll  appear  to  show 
that  the  chief  histological  element  of  the  neuroglia  is  a  multi- 
polar connective-tissue  cell,  whose  processes  are  unbranched. 
They  are  often  described  as  the  "  spider- cells  "  of  Jastrowitz, 
and  as  Deiters's  cells.  Their  nuclei  correspond  to  what  Henle 
described  as  ' '  granules  "  of  the  cord.  These  cells  are  found 
abundantly  in  the  white  matter,  especially  in  pathological 
specimens.     The  neuroglia  is  probably  the  chief  factor  in  the 


552  THE  SPINAL   CORD. 

formation  of  the  so-called  ''gelatinous  substance"  of  the  gray 
matter  (Fig.  158).  The  view  of  Spitzka  regarding  the  gelati- 
nous substance  has  been  mentioned  on  page  263. 

The  regions  of  the  cord  in  which  the  neuroglia  is  most 
apparent  are  proportionately  destitute  of  nerve  cells.  These 
regions  include  (1)  the  periphery  of  the  cord ;  (2)  the  borders 
of  the  fissures ;  (3)  the  circumferential  area  around  the  central 
canal,  and  to  the  mesial  side  of  the  head  of  the  posterior 
horns  (the  substantia  gelatinosa). 

The  preponderance  of  connective  tissue  in  the  posterior 
horns,  in  contrast  to  that  of  the  anterior  horns,  helps  us  to 
interpret  the  frequent  occurrence  of  inflammatory  affections 
in  the  posterior  portions  of  the  cord. 

The  substantia  gelatinosa  is  darker  in  color  than  the  rest 
of  the  connective-tissue  formation  of  the  cord.  For  this  rea- 
son it  was  formerly  classed  as  a  part  of  the  gray  substance. 
In  the  cervical  and  dorsal  regions  of  the  cord  it  presents  an 
oval  outline  in  all  cross- sections,  but  in  the  lumbar  region  it 
becomes  more  circular.  The  tubercle  of  Rolando  may  be  con- 
sidered as  an  extension  of  this  column  upward  into  the  sub- 
stance of  the  medulla. 

APPEARAKCE   OF   A   TRANSVERSE   SECTION   OF  THE   SPINAL   CORD. 

The  arrangement  of  the  gray  and  white  substance  of  the 
spinal  cord  is  seen  only  on  a  transverse  section.  In  order  to 
properly  appreciate  special  points  in  the  construction  of  these 
two  portions,  several  transverse  sections  must  be  made  at  dif- 
erent  heights  in  the  cord,  because  the  relative  proportion  of 
the  gray  and  white  substance  differs  in  the  cervical,  dorsal, 
and  lumbar  regions.  The  regions  usually  selected  for  these 
transverse  sections  are  the  upper  cervical  portion,  the  center 
of  the  cervical  enlargement,  the  center  of  the  dorsal  region, 
the  lumbar  enlargement,  and  the  terminal  portion  of  the  cord. 
In  the  cervical  region,  the  white  substance  is  the  most  abun- 
dant. In  the  dorsal  region,  the  gray  matter  is  relatively 
smaller  than  at  any  other  point.  In  the  lumbar  enlargement, 
the  gray  matter  is  the  most  extensively  developed. 


k 


THE  SPIRAL    GRAY  MATTER. 


553 


When  we  view  the  appearance  of  the  spinal  cord  on  trans- 
verse section,  we  perceive  that  the  gray  matter  is  arranged  in 
the  same  general  way  in  all  of  its  segments.  This  has  been 
compared  to  the  capital  letter  "H,"  because  its  two  lateral 
halves  are  connected  by  a  transverse  band — the  transverse 
commissure  of  the  gray  substance.  Each  lateral  half  of  the 
gray  substance  is  crescent Ic  in  form,  presenting  an  anterior 
and  a  posterior  projection,  termed  the  anterior  and  posterior 
horns.     The  former  of  these  is  broad  and  blunted,  and  does 


J? 


>-' 


Ti 


Fig.  162. — Semi-diagrammatic  tramvei'ne  section  of  the  gray  substance  of  the  cervical  {A) 
and  lumbar  enlargements  {B)  of  the  spinal  cord.      (Erb.) 

A.  rt,  median  group  of  cells ;  6,  antero-lateral  group ;  c,  postero-lateral  group ;  d,  vesicular 
column  of  Clarke.  B.  a,  median  group ;  a\  group  that  appears  first  in  the  lumbar 
region,  possibly  belonging  to  a ;  6,  antero-lateral  group ;  e,  postero-lateral  group. 
Note  that  the  cells  are  few  and  scattered  in  the  posterior  horns,  and  also  that  the 
shape  of  both  horns  differs  markedly  in  A  and  B. 


not  reach  the  surface  of  the  cord.  The  latter  is  thinner  and 
more  pointed,  and  approaches  the  exterior  surface  of  the 
cord  near  the  point  of  attachment  of  the  posterior  roots  of 
the  spinal  nerves. 

The  anterior  horns  are  much  larger  than  the  posterior  in 


554 


THE  SPINAL    CORD. 


the  cervical  region,  but  less  so  in  the  dorsal  and  lumbar. 
They  contain  the  so-called  *' motor  cells." 

The  posterior  horns  are  also  studded  with  nerve  cells,  but 
they  are  smaller  and  more  spindle-shaped  than  the  motor 
cells.  The  posterior  horns  are  very  large  in  the  lumbar  en- 
largement of  the  cord. 

The  motor  cells  are  commonly  multipolar.  One  of  these 
poles  (the  so-called  "axis-cylinder  process")  is  slender  and 
unbranched,  and  tends  to  increase  in  size  as  it  passes  from 
the  body  of  the  cell.  It  is  known  as  the  ''axis-cylinder 
process  "  (Deiters's).  In  favorable  sections  of  the  cord  it  can 
be  traced  into  the  anterior  root  of  a  spinal  nerve.  It  probably 
becomes  continuous  with  the  axis-cylinder  of  a  motor  nerve 
fiber.  The  other  poles  of  the  cell  divide  into  branches  as  soon 
as  they  leave  the  body  of  the  cell,  and  terminate  in  a  delicate 
network  of  nerve  fibrils  (network  of  Gerlach)  which  exists  in 
the  spinal  gray  matter.     The  motor  cells  are  distributed  in 

well-defined  groups,  whose  situation 
changes  somewhat  in  different  re- 
gions of  the  cord.  These  are  shown 
in  the  admirable  drawings  of  Gerlach 
and  Erb  (Figs.  159  and  162). 

The  admirable  diagram  of  Erb 
(Fig.  162)  illustrates  the  differences 
in  shape  of  the  horns  of  the  spinal 
gray  matter  in  the  cervical  and  lum- 
bar regions  of  the  cord,  and  also  the 
arrangement  of  the  motor  cells  of  the 
anterior  horns  into  groups  that  are 
specially  named.  It  will  be  seen  by 
reference  to  the  diagram  that  the  so- 
called  ' '  median, "  •  '  *  antero-lateral, " 
and  ''postero-lateral"  groups  of  cells 
change  their  relations  to  each  other 
at  different  levels  of  the  cord.  Their 
relative  size  also  varies  at  different  levels.  It  will  be  again 
observed  that  the  vesicular  column  {column  of  Clarke)  is  very 


Fig.  163. — A  piece  of  the  white 
substance  of  the  spinal  cord, 
as  seen  on  transverse  section, 
highly  magnified.     (Erb.) 

Note  that  the  nerve  fibers  cut 
across  present  their  axis-cyl- 
inders toward  the  plane  of 
the  section,  and  that  Deit- 
ers's cells  are  apparent.  The 
tattei'  belong  to  the  connective 
tissue  (neuroglia)  of  the  cord, 
but  present  polar  prolonga- 
tions, as  do  the  nerve  cells. 


THE  SPmAL   GRAY  MATTER. 


555 


well  defined  in  the  cervical  region  and  is  wanting  in  the  lum- 
bar region.  This  column  of  cells  seems  to  exist  only  in  those 
segments  of  the  cord  that  are  connected  with  the  thoracic 
and  abdominal  viscera  (Starr). 


Fig.  164. — Section  of  the  cord  below  the  Fig.  165. — Section  of  the  cervical  enlargement 
medulla  oblongata.     (Sappey.)  of  the  cord.     (Sappey.) 

1,  anterior  median  fissure  ;  2,  posterior  median  fissm'e ;  3,  gray  commissure,  much  thicker 
here  than  lower  down ;  4,  white  commissure  formed  by  the  decussation  of  the  ante- 
rior columns ;  5,  anterior  cornu ;  6,  posterior  cornu ;  7,  lateral  cornu. 

1,  anterior  fissure ;  2,  posterior  fissure ;  3,  3,  anterior  columns  of  most  authors ;  4, 4,  lat- 
eral columns  (these  columns  in  reality  pass  beyond  the  anterior  cornua,  and  the  ante- 
rior columns  occupy  less  space  than  is  here  allowed  them) ;  5,  posterior  columns ;  6, 
posterior  commissure  (here  very  narrow) ;  Y,  reticulated  arrangement  of  the  gray  and 
white  matter  at  the  junction  of  the  two  cornua ;  8,  anterior  cornua,  in  which  the 
multipolar  cells  are  distributed  into  three  principal  groups ;  9,  posterior  cornu ;  10, 
fifth  pair  of  cervical  nerves. 

From  the  gray  matter  of  the  cord,  bundles  may  be  seen  to 
jut  out  into  the  lateral  column  of  either  side  between  the 
anterior  and  posterior  horns.  These  are  commonly  desig- 
nated as  the  ''reticular  processes ^"^  {process  of  LenliosseJc). 
They  do  not  apparently  reach  the  periphery  of  the  cord,  as 
those  that  are  prolonged  into  the  anterior  nerve  roots  do.  It 
is  probable  that  some  of  them  contain  fibers  that  connect  the 
vesicular  column  of  Clarke  with  the  direct  cerebellar  column 
(see  Fig.  64). 

Passing  through  the  center  of  the  gray  commissure,  and 
extending  for  the  greater  portion  of  the  length  of  the  cord, 
may  be  seen  a  small  canal— ?^^6  central  canal  of  the  spinal 
cord."^    The  shape  of  the  central  canal  of  the  cord  varies  in 

^  This  canal  is  continuous,  above,  with  the  fourth  ventricle  of  the  brain ;  and  the 
aqueduct  of  Sylvius  is  considered  by  some  anatomists  as  a  continuation  of  it  above  the 


556 


THE  SPINAL   CORD. 


cross -sections  made  at  different  levels.  In  the  cervical  seg- 
ments it  is  oval,  in  the  dorsal  circular,  and  in  the  lower  seg- 
ments heart-shaped  or  T-shaped.  Its  transverse  diameter  is 
greater  in  the  cervical  and  lumbar  enlargements  than  else- 
where. That  portion  of  the  gray  commissure  which  lies  in 
front  of  this  canal  is  sometimes  called  the  '''anterior  gray 
commissure,^''  while  the  portion  which  lies  behind  it  is  called 
the  "posterior  gray  commissure.''''  In  front  of  the  gray  com- 
missure a  band  of  white  nerve  substance  connects  the  two 


Fig.  166. — Section  from  the  dorsal  Fig.  167. — Section  of  the  lumbar  enlargemerU 

region  of  the  cord.     (Sappey.)  of  the  cord.     (Sappey) 

1,  anterior  fissure ;  2,  posterior  fissure ;  3,  anterior  column  situated  within  the  corre- 
sponding cornu,  and  decussating  in  the  median  line  with  the  column  of  the  opposite 
side ;  4,  4,  lateral  column  reachmg  to  the  anterior  column,  but  separated  from  it  by 
no  distinct  line  of  demarkation  ;  5,  posterior  column ;  6,  7,  section  of  the  columns  of 
Clarke,  situated  at  the  two  extremities  of  the  gray  commissure,  at  the  junction  of  the 
anterior  and  posterior  cornua,  and  containing  large  multipolar  cells ;  8,  anterior 
cornu  ;  9,  posterior  cornu ;  10,  posterior  root  of  dorsal  nerves. 

1,  anterior  fissure ;  2,  posterior  fissure ;  3,  3,  anterior  columns  of  most  authors ;  4,  4,  lat- 
eral columns  of  most  authors ;  5,  posterior  column ;  6,  gray  commissure  and  central 
canal,  and,  to  the  right  and  left  of  the  latter,  the  orifices  of  two  longitudinal  veins ; 
7,  reticulated  arrangement  of  white  and  gray  matter ;  8,  anterior  cornu ;  9,  posterior 
cornu ;  10,  posterior  root  of  the  lumbar  nerves. 

lateral  halves  of  the  cord,  to  which  the  term  "anterior''^  or 
"'white  commissure^''  is  applied.  In  the  cervical  segments  of 
the  cord  the  white  commissure  is  thicker  than  the  gray,  but 
the  reverse  is  the  case  in  the  dorsal  and  lumbar  segments. 

The  posterior  horn  divides  the  lateral  half  of  the  cord  into 
two  great  subdivisions,  the  one  lying  anterior  to  it  being 


fourth  ventricle.  It  presents  a  pouch,  the  "  ventriculus  terminalis  "  of  Krause,  at  the 
lower  extremity  of  the  cord.  Below  this  pouch  it  diminishes  in  caliber,  and  is  prolonged 
into  the  "  filum  terminale."     It  is  lined  with  epithelium  throughout. 


Fig.  168. — Diagram  illustrating  the  relations  of  the  nerve-fiber  tracts  in  tJie  spinal  cord. 
The  section  is  supposed  to  be  taken  transversely  through  the  lower  part  of  the  cer- 
vical enlargement.    (Modified  from  Flechsig  and  Hammond  by  the  author.) 

A.  Anterior  Median  Fissure. 

B.  Posterior  Median  Fissure. 

C.  Intermediate  Fissure. 

D.  Anterior  Gray  Comu. 

E.  Posterior  Gray  Cornu.     The  large  part  is  called  the  "  Caput,"  and  the  constricted 

part  the  "  Cervix." 

F.  Gray  Commissure,  with  Central  Canal. 

G.  Direct  Pyramidal  Tract  (Flechsig),  or  Column  of  Tiirck. 

H.  Fundamental  Part  of  the  Anterior  Column  (Anterior  Root  Zones  of  Charcot  and 

his  pupils). 
I.     Anterior  Part  of  Lateral  Column. 
K.   Crossed  Pyramidal  Tract  of  Lateral  Column. 
L.    Direct  Tract  from  Lateral  Column  to  Cerebellum. 

to  extend  forward  to  H. 
M.  Column  of  Burdach,  Posterior   Root  Zones  of  Charcot  and  his  pupils,  Funiculus 

Cuneatus,  Postero-External  Colun^n. 
N.   Column  of  Goll,  Funiculus  Gracilis,  Postero-Median  Column. 
CI.  "Vesicular  Column  of  Clarke. 
S.    Sensory  Tract  of  Lateral  Column,  according  to  view  of  Gowers,  WoroschilofP,  Ott, 

and  others. 
P.    Reticular  Process,  to  left  of  letter,  adjacent  to  the  Cells  of  Clarke's  Column. 

The  posterior  columns  of  descriptive  anatomies  include  the  fields  M  and  N  extending  on 
the  surface  from  B  to  R.  The  antero-lateral  columns  extend  on  the  surface  from 
R  to  A.  Their  anterior  division  includes  the  fields  G  and  H ;  their  lateral  division, 
the  fields  K,  L,  and  L 


By  some,  this  tract  is  believed 


SUBDIVISIONS  OF  THE   WHITE  SUBSTANCE.  557 

frequently  called  the  antero-lateral  column^  and  that  poste- 
rior to  it  being  known  as  the  posterior  column.  In  the  col- 
ored diagram  it  will  be  perceived  that  the  simpler  anatomical 
divisions  of  the  cord  have  been  modified  by  pathological  re- 
searches, so  that  special  regions  in  each  are  now  designated. 
Some  of  these  are  named  after  the  investigator  who  first  dis- 
covered their  function.  Thus,  to-day,  we  more  commonly 
read  of  the  columns  of  Goll,'  of  Turck,  of  Burdach,'  and  of 
the  "anterior  root  zone"  and  the  "posterior  root  zone,"  than 
of  the  anatomical  terms  with  which  you  are  doubtless  more 
familiar.  This  is  not  without  benefit  to  those  who  expect  to 
master  the  mechanism  of  the  symptomatology  of  the  more 
important  types  of  spinal  diseases,  although  it  may  for  a 
while  tend  to  confuse  them.  The  situation  of  lesions  within 
the  cord  can  be  thus  more  simply  expressed  than  by  the  use 
of  terms  which  are  inadequate  to  convey  the  idea.  The  older 
anatomical  subdivisions  of  the  cord  are  fast  becoming  obso- 
lete terms  with  the  neurologist,  since  they  are  based  upon  a 
purely  structural  foundation,  irrespective  of  the  physiological 
functions  of  the  different  parts. 

A  few  words  of  explanation  of  this  diagram  (Fig.  168) 
will  assist  you,  I  trust,  in  mastering  these  new  terms.  You 
will"  perceive  that  the  gray  matter  is  shown  with  its  two  ante- 
rior and  two  posterior  horns  (D  and  E) ;  and  that  the  antero- 
median and  postero- median  fissures  separate  the  cord  into 
two  lateral  halves.  In  the  anterior  part,  lying  on  each  side 
of  the  an tero-median fissure,  are  seen  the  "columns  of  Tiirck" 
(G).  These  are  also  called  the  "direct  pyramidal  columns," 
because  the  nerve  fibers  which  form  them  pass  through  the 
anterior  pyramid  of  the  medulla  and  to  the  cerebral  hemi- 
sphere without  decussation.  On  either  side  of  these  columns, 
extending  backward  toward  the  line  of  the  transverse  com- 

'  The  "column  of  Goll"  is  described  under  the  following  names:  The  funiculus  gra- 
cilis ;  posterior  internal  column  (Grassett) ;  internal  tract  of  posterior  column ;  marginal 
funiculus  (Gratiolet) ;  postero-median  column  (Gowers) ;  dark  posterior  column  (Goll), 

*  The  "  column  of  Burdach "   is  described  under  the  following  names  by  different 
authors :  The  posterior  root  zone  (Charcot) ;  postero-external  column  (Gowers) ;  funiculus 
cuncatus ;  external  fascicle. 
38 


558  TEE  SPINAL   CORD. 

missure  of  the  cord,  are  the  two  regions  (H)  which,  from 
their  relation  to  the  anterior  roots,  are  called  the  "anterior 
root  zones."'  As  we  pass  still  farther  backward,  we  next 
meet  the  two  lateral  columns  (I),  which,  as  you  will  see,  are 
limited  behind  by  the  posterior  horns  of  gray  matter. 

This  lateral  column  is  further  subdivided  into  the  "  direct 
cerebellar  column,"  the  ''crossed  pyramidal  column,"  as 
shown  in  the  diagram,  and  an  unnamed  portion. 

Behind,  and  adjoining  the  posterior  horns  of  gray  matter, 
you   see  two  portions  (M),  the  posterior  root  zones,  or  the  ] 
"  columns  of  Burdach  "  ;  while  upon  either  side  of  the  postero-lj 
median  fissure  lie  the  ''columns  of  GroU"  (N). 

The  "posterior  column"  of  the  ancient  classification,  withal 
which  you  are  familiar,  comprises  the  "columns  of  GoU  and,|J 
of  Burdach."  i 

The  "columns  of  TtJRCK,"  or  the  ''^ direct  pyramidal\ 
column^'' ^  contain  motor  fibers  that  can  be  traced  directly  up-j 
ward  to  the  cerebral  hemisphere  of  the  same  side.  \ 

The  "  CROSSED  PYRAMIDAL  COLUMNS,"  ou  the  Other  hand, 
are  composed  entirely  of  motor  fibers  that  are  associated  with  : 
the  opposite  cerebral  hemisphere.     These  fibers  are  found  to  i 
decussate  within  the  substance  of  the  medulla  at  its  lowest  * 
part,  and  then  to  pass  upward,  in  connection  with  those  fibers 
that  compose  the  column  of  Turck  of  the  opposite  lateral  half  , 
of  the  cord.     These  two  strands  help  to  form  the  so-called 
"anterior  pyramids"  of  the  medulla.     Fig.  169  will  help  to  ; 
render  the  course  of  these  two  bundles  of  fibers  more  intelli-  | 
gibie  to  the  general  reader.    From  both  the  direct  and  crossed  [ 
pyramidal  columns,  fibers  are  constantly  given  off  to  the 
motor  cells  in  the  anterior  horns  of  the   spinal   segments ;  | 
hence  they  become  smaller  and   smaller  from  above  down-  I 
ward,  until  at  last  Tiirck's  columns  disappear  entirely.  j 

The  crossed  pyramidal  column  varies  in  position  as  well  | 
as  in  size  in  the  different  segments  of  the  cord.  .  In  the  cervit  - 
cal  enlargement  it  occupies  a  large  triangular  area  in  the  pos*  I 
terior  half  of  the  lateral  column,  but  it  does  not  reach  thijiii 


*  Called  also  the  anterior  fundamentcU  column. 


A 


THE  PYRAMIDAL  FIBERS. 


559 


Pyramidal  fibers   of   the 
left  cerebral  hemisphere. 


Fibers  of  Tixrck'e  col-  1 
umn  of  kft  half  of  \ 
cord.  -J 

Fibere  of  the  crossed  ~\ 
pyramidal  column  of  r 
the  left  eide  of  cord.    -' 


Pyramidal  fibers  of  the  right  cere- 
bral hemisphere. 


J  Decussation  of  the  crossed  pyra- 
*")     midal  tracts  within  the  me- 
V.    dulla  oblongata. 


f  Fibers  of  Turck's  column  of 
y^     right  half  of  cord. 

{Fiber  of  the  crossed  pyra- 
midal column  of  the  right 
side  of  cord. 


Column  of  Tiirckof  right 
side. 


f  Direct  cerebellar  col- 
\    umn  of  right  side. 
.\  Crossed       pyramidal 

I     column     of    right 

*^    side. 


Fig.  169. — A  diagram  designed  hy  the  author  to  show  the  areas  of  the  crossed  and  direct 
and  crossed  pyramidal  tracts  in  a  section  of  the  spinal  cord^  and  the  fibers  that  corri- 
pose  each. 

a  and  e,  the  pyramidal  (motor)  fibers  going  from  the  left  cerebral  hemisphere  to  the  spinal 
cord ;  b  and  c?,  the  same  of  the  right  cerebral  hemisphere.  Above  the  decussation, 
the  crossed  pyramidal  bundles  lie  nearest  the  median  line.  The  diagram  in  this 
respect  is  incorrectly  drawn. 


560  THE  SPINAL   CORD. 

surface  of  the  cord.  It  diminishes  in  size  as  it  passes  down- 
ward, and  ends  in  the  lumbar  enlargement,  where  it  reaches 
the  periphery  of  the  cord.  It  is  unquestionably  the  chief 
path  for  voluntary  motor  impulses  which  are  sent  out  from 
the  brain  to  the  extremities  or  trunk. 

The  deductions  of  Schultze,  of  Heidelberg,  respecting  the 
motor  tracts  are  based  upon  a  study  of  descending  degenera- 
tion after  compression  myelitis  in  five  cases.  They  are  as 
follows : 

1.  The  degeneration  was  not  confined  exclusively  to  the 
direct  and  crossed  pyramidal  tracts.  It  invaded  also  the 
lateral  and  anterior  column  for  a  distance  of  from  eight  to 
ten  centimetres. 

2.  The  short  fibers  (thus  demonstrated  to  exist)  probably 
act  as  commissural  fibers  for  adjacent  spinal  segments,  and 
carry  centrifugal  impulses. 

3.  The  fibers  which  lie  closest  to  the  gray  matter  in  the 
lateral  column  fail  to  degenerate  in  either  direction.  They 
probably  are  nourished  by  a  cell  at  either  end,  and  are  be- 
lieved by  this  observer  to  constitute  a  component  part  of  the 
reflex  arcs  of  spinal  automatism. 

The  ANTERIOR  ROOT  ZONE  is  that  part  of  the  anterior  col- 
umn which  is  not  occupied  by  the  direct  pyramidal  fibers 
(those  of  Tiirck's  column).  It  seems  to  be  composed  of  fibers 
which  are  destined  to  enter  the  anterior  roots  of  the  spinal 
nerves,  and  possibly  also  of  commissural  fibers  that  serve  to 
connect  the  anterior  horns  of  the  different  segments  of  the 
cord. 

The  LATERAL  COLUMN  of  each  side  (exclusive  of  the 
crossed  pyramidal  tract  and  the  direct  cerebellar  column)  is 
not  yet  well  understood  as  regards  its  construction  or  func- 
tions. It  contains  vaso-motor  and  inhibitory  fibers,  and  pos- 
sibly acts  as  a  tract  of  sensory  conduction  (Gowers,  Woros-  ^ 
chiloff,  Ott,  and  others).  \ 

The  DIRECT   CEREBELLAR   COLUMN  first   appears  in  the    , 
upper  part  of  the  lumbar  enlargement  of  the  spinal  cord  and 
increases  in  size  as  it  passes  upward  toward  the  brain.     It  j 


SENSORY  TRACTS  OF  THE  CORD.  561 

seems  to  receive  libers  which  pass  from  a  group  of  cells, 
called  Clarke's  vesicular  column  (Fig.  170).  The  fibers  of 
which  the  direct  cerebellar  tract  is  composed  are  believed  to 
pass  to  the  superior  vermiform  process  of  the  cerebellum 
directly — i.  e.,  without  the  intervention  of  any  nodal  masses 
of  gray  matter. 

The  course  of  these  fibers  through  the  restiform  body  of 
the  medulla  and  their  ultimate  termination  have  been  consid- 
ered in  the  previous  section. 

The  POSTERO-iN^TERNAL,  or  Goll's  coLUMiN^,  is  composed 
chiefly  of  long  and  short  fibers  derived  from  the  posterior 
horn  of  gray  matter  and  the  gray  commissure.  It  is  proba- 
bly associated  with  the  conduction  of  tactile  sensations  from 
the  legs  upward  to  the  brain. 

The  POSTERO-EXTERNAL,  or  Burdach's  column,  is  com- 
posed (1)  of  fibers  derived  from  the  posterior  roots  of  the 
spinal  nerves  passing  inward  to  join  the  posterior  horn,  (2)  of 
fibers  that  convey  tactile  impressions  from  the  upper  limbs 
to  the  brain ;  and  (3)  possibly  of  commissural  fibers  which 
connect  the  posterior  horns  of  the  various  spinal  segments. 

Ott  believes  that  all  the  sudorific  and  inhibitory  fibers  of 
the  spinal  cord  decussate,  as  well  as  the  motor,  sensory,  and 
vaso-motor  fibers.  He  places  the  tract  of  the  sudorific  and 
itihibitory  fibers  in  the  lateral  column  of  the  cord,  and  also 
some  fibers  of  sensation.  He  supports  the  view  that  the 
posterior  columns  are  physiologically  associated  with  the 
transmission  of  tactile  sensations.  In  reference  to  the  func- 
tion of  the  gray  matter  as  a  medium  of  conduction,  this 
experimenter  differs  from  the  view  of  Schiff  that  afferent 
impulses  may  be  carried  in  all  directions.  It  is  probable, 
however,  that  the  paths  for  reflex  action  are  in  the  gray 
matter.  He  disputes  the  statement  of  Brown-Sequard  that 
the  anterior  columns  carry  fibers  of  sensation. 

The  late  researches  of  Starr  in  reference  to  the  course  of 
the  sensory  tracts  partly  sustain  the  opinion  of  Schiff,  deduced 
from  experimentation  upon  animals,  viz.,  that  the  sensations 
of  touch  and  of  the  muscular  sense  pass  upward  along  the 


562  THE  SPINAL   COUD. 

posterior  columns  of  the  cord,  and  that  the  sensations  of  tem- 
perature and  of  pain  travel  either  in  the  spinal  gray  matter 
or  the  direct  cerebellar  columns. 

He  believes  that  the  columns  of  Goll  transmit  the  im- 
pressions of  the  muscular  sense  pertaining  to  the  legs^  and 
those  of  Burdach  impressions  of  a  similar  kind  from  the  upper 
extremities. 

He  excludes,  however,  the  view  that  the  direct  cerebellar 
columns  carry  sensations  of  pain  or  of  temperature,  because 
these  tracts  do  not  extend  below  the  first  lumbar  segment  and 
because  they  end  in  the  cerebellum.  Lesions  of  this  ganglion 
have  never  been  shown  to  cause  defective  appreciation  of  pain 
or  of  temperature.  He  therefore  places  the  paths  of  conduc- 
tion of  these  two  varieties  of  sensations  in  the  spinal  gray 
matter. 

Respecting  the  function  of  the  direct  cerebellar  columns, 
this  author  advances  a  hypothesis  that  centripetal  impulses 
from  the  organs  within  the  great  cavities  of  the  trunk  are 
conveyed  by  these  columns  to  the  cerebellum  and  excite  (in 
the  reflex  centers  of  this  ganglion)  the  impulses  necessary  to 
their  normal  functions.  He  supports  this  view  from  three 
standpoints,  as  follows : 

1.  An  anatomical  one,  because  the  limits  of  the  direct  cere- 
bellar columns  coincide  with  the  entrance  into  the  cord  of  the 
nerves  associated  with  the  thoracic  and  abdominal  viscera. 

2.  Because  lesions  of  these  columns  are  attended  with 
irregular  action  of  the  functions  of  the  viscera  ;  as,  for  ex- 
ample, gastric  crises  and  habitual  constipation.     . 

3.  Because  lesions  of  the  cerebellum  have  been  shown  to 
give  rise  to  functional  disturbances  of  the  abdominal  viscera  ; 
such  as  indigestion,  vomiting,  obstinate  constipation,  poly- 
uria, albuminuria,  etc. 

Schultze  has  carefully  studied  the  results  of  five  cases  of 
compression  myelitis  with  special  reference  to  the  secondary 
degeneration,  which  was  thus  induced  within  the  motor  and 
sensory  spinal  tracts.  His  published  conclusions  regarding 
the  sensory  tracts  may  be  summarized  as  follows : 


SENSORY  TRACTS  OF  THE  CORD.  563 

1.  Degeneration  of  the  posterior  columns  was  of  the  as- 
cending type,  and  was  confined  to  the  columns  of  Goll  when 
all  the  nerves  below  the  eleventh  dorsal  were  severed  from 
their  indirect  connection  with  the  brain  through  the  cord. 

2.  That  long  and  short  fibers  exist  in  the  posterior  col- 
umns. The  longest  centripetal  fibers  of  the  spinal  cord  lie  in 
the  columns  of  Goll  in  its  inner  and  posterior  part. 

3.  That  the  fibers  for  the  sciatic  nerves  lie  nearest  to  the 
median  line  and  farthest  back  in  GolF  s  columns.  That  those 
of  the  crural  nerves  are  packed  next  to  these,  and  bound 
there  both  anteriorly  and  laterally.  Finally,  that  the  dorsal 
nerves  fill  up  the  remainder  of  Goll's  column  and  a  part  of 
Burdach's  column. 

4.  The  short  fibers  of  Goll's  column  probably  end  in  the 
spinal  segments.    The  long  fibers  are  prolonged  to  the  medulla. 

5.  Some  fibers  of  the  posterior  nerve  roots  descend  after 
entering  the  cord  for  a  distance  of  two  or  three  centimetres. 

6.  He  places  the  anterior  limits  of  the  direct  cerebellar 
columns  farther  forward  than  Flechsig,  and  states  that  they 
reach  the  point  where  the  fibers  of  the  anterior  nerve  roots 
escape. 

7.  The  columns  of  Burdach  contain  all  the  fibers  which 
enter  the  cord  from  the  posterior  roots  of  the  cervical  nerves, 
as  well  as  some  from  the  dorsal  nerves.  .^ 

8.  The  fibers  of  the  direct  cerebellar  appear  to  undergo 
complete  degeneration  only  after  a  lesion  which  lies  above 
the  last  dorsal  segment. 

Much  of  our  knowledge  of  the  course  of  fibers  within  the 
spinal  cord  is  no  longer  speculative.  Flechsig  has  shown  that 
definite  tracts  of  fibers  within  the  spinal  cord  are  developed 
at  different  periods,  as  the  cut  introduced  (Fig.  170)  clearly 
demonstrates,  and  also  that  the  relative  proportion  of  motor 
fibers  within  the  direct  and  crossed  pyramidal  fasciculi  varies 
with  individuals. 

We  know  also  that  secondary  degeneration  of  nerve-tracts 
occurs  when  they  are  cut  off  from  their  so-called  "trophic 
centers''^  by  traumatism  or  disease-processes.     This  degenera- 


564 


THE  SPINAL   CORD. 


tion  always  (?)  progresses  in  the  direction  of  the  currents  that 
are  conveyed  hy  the  fibers  whose  nutrition  is  affected  ; '  hence 
it  progresses  downward  in  the  motor  tracts  and  upward  in  the 
sensory  tracts. 

Finally,  experimental  physiology  has  now  determined 
many  facts  with  an  approach  to  accuracy  that  were  long  in 
dispute,  and  has  thus  aided  us  in  properly  interpreting  symp- 


PiQ.  170. — A  diagram  Ulmtrating  the  development  of  the  different  systems  of  fibers  in 
the  spinal  cord.     (Flechsig.) 

I,  section  at  level  of  third  cervical  nerves ;  II,  at  level  of  fifth  cervical ;  III,  at  level  of 
sixth  dorsal;  IV,  at  level  of  fourth  lumbar  nerves;  1,  principal  mass  of  anterior 
columns ;  2,  Burdach's  columns ;  3,  lateral  columns ;  4,  lateral  boundary  of  gray 
substance ;  5,  columns  of  GoU ;  6,  direct  cerebellar  columns ;  7,  crossed  pyramidal 
columns ;  7',  Tiirck's  columns ;  y,  anterior  roots.  Note  that  Tiirck's  columns  disap- 
pear in  IV ;  that  Goll's  columns  increase  in  size  from  below  upward ;  that  the  direct 
cerebellar  columns  appear  in  III,  and  increase  in  size  in  II  and  I ;  that  the  crossed 
pyramidal  columns  reach  the  surface  in  IV ;  and  that  the  shape  of  the  gray  substance 
differs  in  all  the  sections. 

toms  referable  to  spinal  disease.  We  are  now  enabled  to  state 
positively  that  the  ''  columns  of  Goll  and  Burdach,"  as  well 
as  the  "direct  cerebellar  column,"  conduct  centripetal  or  sen- 


*  Spitzka  advances  some  pathological  observations  to  prove  that  this  rule  has  some 
apparent  exceptions. 


CONDUCTING   TRACTS  OF  THE  CORD. 


566 


sory  impulses,  while  the  "  columns  of  Tiirck " and  the  ''crossed 
pyramidal  tracts"  conduct  centrifugal  or  motor  impulses. 
Some  portions  of  the  spinal  cord  are,  however,  still  in  dis- 
pute, because  their  special  functions  are  not  as  yet  definitely 

ascertained. 

ar 


Fig.  171. — Diagram  of  a  transverse  section  of  spinal  cord  in  upper  half  of  dorsal 

region.     (Flechsig.) 

c,  anterior  commissure ;  dc,  fibers  which  pass  from  the  vesicular  column  of  Clarke  {vc) 
to  the  direct  cerebellar  tract ;  F,  posterior  horn ;  Ft,  crossed  pyramidal  column ; 
T,  direct  pyramidal  columns ;  dr,  direct  cerebellar  ti'act ;  ar,  internal  part  of  ante- 
rior root  zone ;  ar\  external  part  of  same ;  pr^  posterior  root  zone ;  G,  columns  of 
Goll ;  /r,  reticular  formation  of  spinal  cord  ;  a,  anterior  horns. 


The  cut  of  Flechsig's  now  introduced  will  enable  you  to 
grasp  the  general  direction  and  distribution  of  some  of  the 
fibers  of  the  spinal  cord.  It  shows  (1)  the  cut  ends  of  the 
fibers  which  make  up  the  mass  of  the  various  columns,  and 
(2)  the  course  pursued  by  the  motor  and  sensory  fibers  which 
join  the  cord  at  the  level  of  the  section.  Although  this  cut 
is  purely  diagrammatic,  it  is  admirably  devised  to  bring  out 
certain  salient  points  in  spinal  architecture,  to  which  refer- 
ence will  be  made  later.  The  descriptive  text  of  the  cut  will 
render  it  intelligible  to  the  reader. 


666  THE  SPINAL   CORD. 


FUKCTIOKS   OF  THE   SPIN^AL  COED. 


These  questions  may  naturally  arise  in  reference  to  the 
previous  pages :  Why  is  such  a  digression  from  previously 
accepted  terms  so  universally  used,  in  preference  to  those 
more  familiar  and,  possibly,  simpler  terms  of  nomenclature  ? 
Why  should  the  columns  of  Tiirck,  Goll,  and  Burdach  be 
separated  from  each  other  when  no  anatomical  line  of  divis- 
ion seems  to  have  been  created?  Is  the  arrangement  not  a 
strained  attempt  to  mystify  and  confuse  the  medical  reader, 
and  does  a  sufficient  ground  exist  for  so  great  a  departure 
from  previous  methods  of  description  ?  In  reply  to  such 
anticipated  questions  —  and  they  have  been  asked  of  me 
many  times — I  vrould  respectfully  draw  your  attention  to 
such  points  in  the  physiology  and  pathology  of  the  spinal 
cord  as  will  help  to  show  the  necessity  which  existed  for 
modification  of  previously  familiar  terms,  as  well  as  the 
advantages  which  are  gained  by  those  subdivisions  of  the 
cord  which  are  accepted  to-day  by  every  specialist  on  nervous 
diseases. 

In  order  to  properly  appreciate  many  of  its  functions,  the 
spinal  cord  must  be  regarded  as  a  mass  of  superimposed 
segments  united  together^  rather  than  as  an  individual  whole. 
Each  spinal  segment  consists  of  a  disk  of  the  spinal  cord 
with  one  pair  of  spinal  nerves  attached..  Such  a  segment  is, 
to  all  intents  and  purposes,  an  independent  structure  under 
certain  circumstances.  The  following  diagram  will  illustrate 
the  construction  of  a  spinal  segment. 

It  will  be  perceived  that  each  disk  of  the  spinal  cord  has 
attached  to  it  one  pair  of  spinal  nerves.  These  arise  from  it 
by  an  anterior  or  motor,  and  a  posterior  or  sensory  root. 
Upon  t^^e  latter  is  a  ganglionic  enlargement^  as  is  usually 
the  case  with  all  nerves  that  are  sensory  in  function.  It  will 
be  seen  that  the  two  roots  unite  to  form  a  so-called  spinal 
nerve  ;  hence  every  spinal  nerve  possesses  motor  and  sensory 
fibers.  Some  sympathetic  or  vaso-motor  fibers  are  also  pres- 
ent in  spinal  nerves.     These  are  not  shown  in  the  diagram. 


REFLEX  PATHS  OF  TEE  CORD. 


567 


Each  spinal  segment  is  connected  by  means  of  its  nerves 
with  definite  areas  of  the  body.  It  is  capable  of  receiving 
sensory  impressions  from  these  areas  by  means  of  its  pos- 


SENSOHV 

BH&UCH 


Fig.  1Y2. — Diagram  of  a  spinal  segment  designed  by  the  author  to  show  its  component  parts. 

terior  roots,  and  of  transmitting  in  return  motor  impulses 
to  them  by  means  of  its  anterior  roots.  The  gray  matter  of 
the  siDinal  segment,  by  means  of  the  nerve  cells  imbedded 
within  it,  can  therefore  be,  under  some  circumstances,  an 
agent  of  automatic  reflex  movement  in  response  to  some  sen- 
sory impression  received  from  without  (Fig.  173). 


Fig.  173. — A  diagram  designed  by  the  author  to  illustrate  the  circle  of  reflex  action 
'  segment.     (Modified  from  Bramwell.) 


1,  sensory  fibers  from  skin,  tendons,  joints,  etc. ;  2,  sensory  fibers  from  muscles ;  3,  motor 
cell  of  anterior  horn  of  spinal  gray  matter  (A.  H.),  Joining  with  1  and  2 ;  4,  motor 
fibers  given  off  from  3,  and  escaping  by  anterior  root  to  supply  the  muscles ;  5,  fiber 
Joining  ganglionic  cell  (3)  with  the  crossed  pyramidal  tract  (C.  P.  C.)  coming  from  the 
brain ;  6,  ganglion  on  posterior  root  of  spinal  nerve  ;  7,  fiber  Joining  3  with  Tiirck's 
column  (T).  It  will  be  noticed  that  some  sensory  fibers  (2)  reach  3  by  passing- 
through  Burdach's  column  (B),  while  others  (1)  pass  through  the  posterior  horn  of 
gray  matter  (P)  to  reach  the  ganglionic  cell  (3). 


668  THE  SPINAL   COBD. 

It  often  becomes  necessary,  when  disease  of  the  spinal 
cord  is  suspected,  to  test  the  excitability  of  the  different  seg- 
ments of  the  cord  separately,  either  by  stimulation  of  the 
skin  of  different  regions  or  by  increasing  the  tension  of  cer- 
tain muscles  by  a  blow  upon  their  tendons,  after  they  have 
been  partially  put  upon  the  stretch.  The  muscular  reactions 
that  ensue  are  known  as  the  ''  superficial  "or  ''  skin  reflexes," 
and  the  ''deep"  or  '* tendon  reflexes."  They  will  be  dis- 
cussed later. 

The  spinal  segments  are  connected  (1)  by  certain  nerve 
tracts  that  pass  uninterrui)tedly  to  the  brain  (Fig.  174),  and 
(2)  by  certain  commissural  fibers  that  simply  serve  as  con- 
necting links  between  different  segments  along  the  chain. 
The  admirable  diagrams  of  Bramwell,  which  I  have  modified 
somewhat,  illustrate  many  points  in  the  physiology  of  the 
spinal  cord  better  than  a  long  verbal  description. 

It  will  be  seen  in  Fig.  175  that  the  motor  tracts  compos- 
ing the  column  of  Turck  and  the  crossed  pyramidal  tract 
of  each  lateral  half  of  the  cord  (if  traced  upward  in  the  dia- 
gram) become  united  in  the  medulla  (one  decussating  and  the 
other  not)  and  then  pass  to  the  cerebrum.  Each  of  these  sub- 
divisions of  the  motor  tract  gives  off  branches  to  the  gray 
matter  of  each  spinal  segment.  These  branches  unite  with 
the  motor  cells  of  the  anterior  horn  of  the  corresponding  side 
— probably  through  the  network  of  Gerlach  (Fig.  160).  Sub- 
sequently these  branches  are  continued  from  the  bodies  of  the 
motor  cells  to  the  anterior  root  of  the  spinal  nerve  of  the 
same  side,  as  the  "axis-cylinder  process"  of  each  cell.  The 
motor  tract  derived  from  the  cerebrum,  therefore,  is  con- 
stantly depleted^  in  regard  to  the  number  of  fibers  of  which 
it  is  composed,  as  it  descends  the  cord.  It  finally  terminates 
in  the  motor  cells  of  the  last  spinal  segment.  By  the  inter- 
polation of  a  motor  cell  for  each  fiber  in  the  conducting  path 
from  the  brain,  every  spinal  segment  is  enabled  to  exert  an 
automatic  action  upon  the  muscles  supplied  by  its  motor  fila- 
ments ;  yet,  at  the  same  time,  the  brain  can  overpower  this 
automatism  when  necessary,  by  means  of  its  connection  with 


ji 


MOTOR  AND  SENSOBY  SPINAL   TRACTS, 


569 


DM, 

Fig.  IVi. — A  diagram  designed  to  illustrate  the  paiJis  of  motor  and  sensor^/  conduction 
in  the  spinal  cord.     (Modified  from  Bramwell.) 

D.  C,  direct  cerebellar  tracts  ;  C.P.,  crossed  pyramidal  tracts;  G.,  sensory  tracts  of  the 
columns  of  Goll ;  T.,  direct  pyramidal  tracts,  or  those  of  Tiirck's  columns.  The 
arrows  show  the  direction  of  the  conduction,  two  being  centripetal  or  sensory,  and 
two  centrifucral  or  motor. 


570  TEE  SPINAL   CORD. 

the  spinal  cells,  and  exercise  its  control  over  the  same 
muscles  independently  of  the  spinal  segment.  In  some  forms 
of  disease,  in  which  the  controlling  influence  of  the  brain  is 
impaired  or  destroyed,  the  spinal  segments  (left  free  to  act 
without  restraint)  give  rise  to  an  exaggeration  of  the  tendon- 
reflexes.     This  condition  is  of  great  clinical  interest. 

In  disease  of  the  spinal  cord,  all  the  muscles  associated 
with  the  segments  of  the  cord  attacked  are  in  some  cases 
not  equally  paralyzed  or  atrophied  ;  thus  demonstrating  that 
some  are  more  easily  disturbed  by  central  influences  than  | 
others.  Allen  has  collected  several  reported  cases  of  special 
interest  in  this  connection ;  That  reported  by  Charcot  and 
Jeffroy  of  infantile  paralysis,  followed  by  death  in  the  fortieth 
year,  exhibited  atrophy  of  both  psoas  muscles,  the  pectoralis 
major,  deltoid,  and  triceps  of  the  left  side,  and  the  deep 
flexors  of  the  fingers  of  the  right  side.  A  case  reported  by 
Barth  showed  an  atrophy  of  the  supinators  of  the  left  fore- 
arm, and  the  quadratus  femoris  and  gastrocnemius  of  both 
sides.  Vulpian  mentions  a  case  in  which  all  the  mnscles  of 
the  right  leg,  except  the  extensor  communis  digitorum,  were 
fatty ;  in  the  thigh,  the  rectus  femoris  and  the  vastus  internus 
were  fatty,  and  the  vastus  externus  was  not. 

Certain  clinical  facts  can  be  adduced  to  support  the  view 
that  the  extensor  nerves  are  associated  with  centers  within 
the  cord  that  become  exhausted  under  depressing  influences, 
as  in  the  lease  of  lead  and  diphtheritic  poisoning,  sooner  than 
the  centers  governing  the  flexors.     It  is  also  well  recognized 
that  the  flexor  muscles  are  the  chief  agents  in  producing 
various  forms  of  post-paralytic  contracture  and  deformity.   \ 
When  descending  degeneration  exists  high  up  in  the  fibers  of  j 
the  crossed  pyramidal  columns,  the  arm  gradually  becomes 
'flexed  upon  the  chest,  the  forearm  becomes  flexed  upon  the  ' 
arm,  and  the  hand  flexed  upon  the  forearm.     Subsequently    ■ 
the  lower  limbs  exhibit  similar  effects  of  muscular  contract-    j 
ure.     The  normal  excess  of  power  of  the  flexors  over  the  ex- 
tensors may  partly  explain  the  characteristic  deformities  that  'i 
ensue  when  the  fibers  of  the  lateral  columns  are  involved  in    ; 


CONNECTIONS  OF  SPINAL   CONDUCTING   TRACTS.       571 


\G       CP 

Fig.  175. — A  diagram  designed  to  illustrate  the  connections  of  the  motor  and  sensory  con- 
ducting tracts  with  the  spinal  nerves.  (Modified  from  Bramwell.)  The  lettering  is  the 
same  as  in  Fig.  114. 

M.  motor  fibers  of  the  anterior  root  of  a  spinal  nerve ;  S,  S',  sensory  fibers  of  the  poste- 
rior root.  Note  that  the  course  of  S  and  S'  are  not  the  same.  Some  sensory  fibers 
pass  through  the  posterior  horn  of  the  spinal  gray  matter,  and  others  through  *Bur- 
dach's  column.  The  direct  cerebellar  column  is  connected  with  Clark's  column  of 
cells.  The  two  pyramidal  tracts  are  united  with  the  motor  cells  of  the  anterior  horns 
of  the  spinal  gray  matter. 


572 


THE  SPINAL   CORD. 


degenerative  processes,  but  we  are  forced  to  recognize  also  a 
peculiar  susceptibility  of  the  extensor  nerves  to  impairment 
of  their  function  from  causes  that  do  not  affect  the  flexor 
nerves  to  the  same  degree,  if  at  all. 

The  diagram  (Fig.  175)  represents  the  sensory  nerve  fibers 
as  undergoing  a  total  decussation  and  passing  upward  to 
the  brain  in  the  column  of  Goll  of  the  opposite  half  of  the 
spinal  segment.  It  shows  that  the  sensory  nerve  fibers  pass 
first  from  the  posterior  root  to  the  column  of  Burdach ; 
and,  after  traversing  its  substance,  a  decussation  by  means 
of  the  gray  commissure  of  the  cord  takes  place.  Now,  this 
arrangement  probably  admits  of  some  modification.  It  is 
by  no  means  proved,  as  yet,  that  all  of  the  sensory  fibers  of 
the  cord  decussate.     Those  which  convey  impressions  of  the 


Fig.  176. — A  diagram  designed  by  the  author  to  represent  the  various  paths  of  sensory 

conduction  in  the  cord. 

A,  direct  cerebellar  column,  receiving  fibers  from  Clarke's  column  (E)  of  the  same  side ; 
B,  Goll's  column,  receiving  fibers  from  the  opposite  nerve  root  by  means  of  the  pos- 
terior gray  commissure ;  C,  ganglion  cell  of  anterior  horn  joining  with  its  sensory 
fibers ;  D,  sensory  tract  of  W'oroschiloff,  Gowers,  and  Ott,  in  the  lateral  column  of  the 
cord.   The  connections  of  this  tract  (if  it  exists  in  the  human  species)  are  not  known. 


muscular  sense  probably  do  not,  until  they  reach  the  me-  \ 

dulla.     Again,  it  is  still  a  matter  of  uncertainty  where  the  j 

main  sensory  tracts  can  be  definitely  placed,  and  whether  \ 

more  than  one  may  not  exist.     Finally,  some  clinical  facts  as  i 


FIBERS  OF  SPmAL  NERVE  ROOTS,  575 

well  as  those  lately  obtained  by  experimentation  favor  the 
view  that  the  sensations  of  pain,  touch,  and  temperature  do 
not  follow  the  same  paths  of  conduction  in  the  spinal  cord. 
It  is  highly  probable  that  all  the  sensory  nerves  eventually 
decussate,  but  it  is  believed  by  many  physiologists  of  the 
present  day  that  some  of  the  sensory  fibers  ascend  for  a 
greater  or  less  distance  within  the  substance  of  the  corre- 
sponding lateral  half  of  the  cord  before  they  cross  to  the  side 
opposite  to  that  upon  which  they  entered  it.  Some  authori- 
ties also  believe  that  the  sensory  nerves  connected  with  the 
tendons,  muscles,  and  fasciae  pass  through  Burdach's  column 
of  the  same  side,  while  those  connected  with  the  skin  traverse 
the  gray  matter  of  the  posterior  horn.  They  thus  endeavor 
to  explain  the  abolition  of  the  deep  or  tendon  reflexes  in  loco- 
motor ataxia,  because  that  condition  is  characterized  by  a 
change  in  the  columns  of  Burdach  that  would  tend  to  impair 
the  conduction  of  any  filaments  passing  through  its  sub- 
stance. 

We  may,  therefore,  draw  the  following  deductions  : 

1.  The  fibers  of  the  nerve  roots  eventually  pass  to  and 
enter  the  gray  substance  of  the  cord,  but  not  by  the  same 
channels  in  all  cases.  In  the  case  of  the  posterior  roots,  some 
fibers  probably  form  an  exception  to  this  rule. 

2.  The  fibers  of  the  anterior  roots  become  joined  to  the 
processes  of  the  nerve  cells  of  the  gray  matter.  This  state- 
ment can  not  be  made  with  the  same  degree  of  positiveness  in 

i  respect  to  the  fibers  of  the  posterior  root. 

3.  From  the  ganglion  cells  of  the  gray  matter  the  fibers  of 
the  anterior  roots  are  connected  with  the  brain  through  the 
white  matter  of  the  cord  by  one  of  three  channels :  1.  By 
entering  the  lateral  columns  of  the  same  side  (the  so-called 
crossed  pyramidal  column).  .  2.  By  entering  the  anterior  col- 
umn of  the  same  side  (the  column  of  Turck).  3.  By  passing 
to  the  opposite  anterior  and  lateral  columns  through  the 
white  commissure  of  the  cord  (decussation  within  the  cord). 
Fig.  175  shows  the  first  two,  and  Fig.  171  the  third,  in  a: 
diagrammatic  way. 

39 


574  TEE  SPINAL   CORD, 

4.  The  processes  of  the  ganglion  cells  of  the  cord  take 
every  variety  of  direction.     Some  anastomose  with  other  cell- 
processes  of  the  same  side  ;  some  join  with  those  of  the  oppo- 
site half  of  the  cord,  by  means  of  the  gray  commissure  ;  some, 
unite  directly  with  the  fibers  of  the  nerve  roots ;  some  are] 
associated  with  the  fibers  of  the  main  conducting  tracts  thai 
are  connected  with  the  brain ;  while  a  few  pass  into  the  white^ 
columns  of  the  cord  and  then  appear  to  ascend  within  them. 

5.  Individual  fibers  of  the  anterior  and  posterior  nerve 
roots  probably  meet  each  other  indirectly  by  means  of  the 
processes  of  the  nerve  cells. 

6.  A  few  fibers  of  the  anterior  roots  ajjpear  to  traverse  the  \ 
gray  substance  and  then  to  pass  into  the  anterior  part  of  the  | 
lateral  column.     Their  function  is  not  known.  j 

7.  The  fibers  of  the  posterior  roots  probably  reach  the  cells  ' 
of  the  posterior  horn  by  means  of  a  network  of  fibers.  j 

8.  Fibers  pass  from  Clarke's  column  of  cells  (Fig.  176)  to  j 
the  direct  cerebellar  column  of  the  same  side.  j 

9.  Some  medullated  fibers  appear  to  rise  directly  f rom  | 
Gerlach's  network  of  fine  fibers,  rather  than  from  a  spinal  cell  \ 
directly. 

Brown- Sequard  was  led  to  believe  that  the  paths  of  the  I 
so-called  "muscular  sense"  entered  at  the  anterior  nerve  ^ 
roots  and  passed  up  in  the  anterior  columns  of  the  gray  sub-  : 
stance  of  the  cord.  As  this  is  not  now  regarded  as  true,  it  \ 
is  not  to  be  classed  as  an  exception  to  all  other  paths  of  sen-  \ 
sory  conduction.  It  is  probable  that  the  fibers  concerned  in  j 
the  sensation  of  muscular  sense  do  not  decussate  within  the 
cord  (Schiff  and  Brown- Sequard).  These  fibers  assist  to  form  ■ 
the  so-called  "pinniform  decussation"  of  the  medulla  (Starr),  x 

Let  us  now  consider,  more  in  detail,  the  various  functions  ■ 
of  the  spinal  cord.  \ 

I  would  call  attention  first  to  the  fact  that  the  spinal  cord  ] 
is  an  organ  of  conduction.     All  voluntary  motor  impulses,  I 
which  affect  the  muscles  of  the  different  parts  of  the  body,  ; 
are  unquestionably  transmitted  from  the  brain  through  the 
cord  to  the  part  destined  to  be  acted  upon.     We  know  that  \ 

\ 


PATHS  FOR  SPINAL   TRANSMISSION.  5T5 

centrifugal  impulses  may  be  created  in  the  cord  itself,  and 
may  also  be  transmitted  from  tlie  brain.  We  see  this  illus- 
trated in  the  hemiplegias  of  cerebral  origin  and  in  the  spinal 
reflexes.  We  also  have  equally  positive  proof  that  certain 
sensory  impressions  are  conducted  by  means  of  the  spinal 
cord  to  the  brain  ;  hence,  centripetal  impulses  or  impressions 
pass  upward  in  some  instances  throughout  the  entire  length 
of  the  cord.  We  see  this  fact  verified  in  the  hemi-ansesthesia 
which  often  accompanies  motor  paralysis  of  cerebral  origin. 
Now,  it  can  be  stated,  with  an  approach  to  accuracy,  that  it 
is  as  certainly  j)roved  that  the  motor  impulses  travel  along 
the  anterior  half  of  the  spinal  cord,  while  the  path  of  sen- 
sory impressions  is  intimately  associated  with  the  posterior 
half  of  the  spinal  cord. ' 

I  would  direct  attention,  in  the  second  place,  to  the  fact 
that  the  motor  fibers  associated  with  the  anterior  roots  prob- 
ably do  not  decussate "  until  they  reach  the  medulla  oblon- 
gata, while  the  sensory  fibers  found  in  the  posterior  roots 
probably  ascend  in  the  columns  of  Burdach  for  a  short  dis- 
tance only,  when  they  pass  into  the  gray  matter  of  the  oppo- 

'  This  statement  is  only  approximately  correct,  as  has  been  shown  in  the  text  of  pre- 
ceding pages.  The  postero-median  columns  (those  of  GoU)  are  composed  chiefly  of  long 
fibers  that  pass  to  the  medulla,  and  are  believed  to  convey  sensations  from  the  lower 
limbs  only.     These  fibers  can  then  be  traced  upward,  as  shown  in  diagram  lYS. 

The  posterolateral  columns  (those  of  Burdach)  are  composed  of  short  fibers  below  the 
cervical  segments,  and  of  long  fibers  above  that  level.  These  pass  in  part  from  the  pos- 
terior roots  of  the  spinal  nerves  and  go  to  the  spinal  gray  matter.  Commissural  fibers 
between  the  various  spinal  segments  are  believed  to  form  a  part  of  these  columns.  In 
the  cervical  region,  this  column  has  been  shown  to  contain  longer  fibers  that  pass  to  the 
medulla.  These  are  supposed  by  some  authorities  (Schultze  and  Flechsig)  to  convey  sen- 
sations from  the  upper  limbs. 

The  direct  cerebellar  column  is  unquestionably  associated  with  the  transmission  of 
sensory  impulses.  Its  fibers  arise  from  the  cells  of  the  column  of  Clarke.  It  terminates 
above  in  the  cortex  and  central  gray  matter  of  the  vermiform  process  of  the  cerebellum, 
after  passing  through  the  inferior  peduncle  of  the  cerebellum.    ^ 

The  gray  matter  of  the  cord  assists  without  doubt  in  the  transmission  of  sensations 
to  the  higher  ganglia.  Whether  the  hypothesis  that  sensory  fibers  are  contained  in  the 
white  substance  of  the  cord  that  lies  between  the  direct  cerebellar  columns  and  the  gray 
matter  can  be  considered  as  proven  is  as  yet  a  matter  of  justifiable  doubt. 

^  As  regards  this  point,  Brown-Sequard  says,  "  In  animals,  there  seems  to  be  in  the 
spinal  cord  itself  a  decussation  of  a  few  of  the  motor  conductors."  I  do  not  think,  how- 
ever, that  such  a  decussation  can,  as  yet,  be  verified  in  man.  If  such  decussation  does 
exist,  it  is  present  only  in  the  cervical  region,  and  not  in  the  dorsal  and  lumbar  regions. 


576  THE  SPINAL   CORD. 

site  half  of  the  cord.  You  can,  therefore,  understand  why 
any  interference  with  the  motor  fibers  (if  below  the  medulla) 
produces  motor  paralysis  on  the  corresponding  side^  while 
any  interference  with  the  sensory  fibers  produces  ancesthesia 
on  tJte  opposite  side  of  the  body. 

Again,  the  antero-lateral  columns  of  the  cord,  which  com- 11 
prise  the  portion  situated  between  the  antero-median  fissure  1 
and  the  point  of  attachment  of  the  posterior  roots  of  the  I 
spinal  nerves,  are  not  markedly  sensible  to  any  form  of  direct 
irritation.'  This  is  a  point  of  some  clinical  interest,  since,  in  . 
certain  morbid  conditions,  a  marked  change  in  this  respect  | 
occurs,  and  the  inexcitable  portions  may  then  give  rise  to  j 
abnormal  sensations  and  to  spasm  of  the  muscles.  If  these  j 
columns  be  divided,  "Goluntary  motion  is  lost  in  all  the  parts  , 
below  the  point  of  section  ;  while,  if  all  the  other  portions  of  j 
the  cord  be  divided,  leaving  the  antero-lateral  columns  intact,  : 
the  power  of  voluntary  motion  remains.  v 

The  gray  matter  of  the  cord,  seems  to  be  intimately  associ- 1 
ated  with  the  transmission  of  certain  varieties  of  sensory  im-  \ 
pressions  to  the  brain,  and  that  portion  which  lies  in  close  j< 
relation  to  the  central  canal  of  the  cord  is  apparently  the  • 
most  important  of  its  transmit tory  apparatus.'  If  the  entire  ^ 
gray  substance  of  the  cord  be  divided,  little  or  no  injury  ^ 
being  done  to  the  white  substance,  all  pgwer  of  perceiving  ' 
sensations  of  pain  seems  to  be  destroyed  below  the  point  of  1 
section. 

Some  late  experiments  by  Woroschiloff,  made  in  Ludwig's  \ 
laboratory,  seem  to  lead  strongly  toward  the  conclusion  that  ^ 
the  older  view  of  physiologists  (who  taught  that  sensations  of  i 
pain  traveled  up  the  cord  in  the  gray  matter,  and  those  ' 
of  touch  and  temperature  in  the  posterior  column  of  the(i^ 
cord)  is  perhaps  erroneous.  Ott  has  lately  confirmed  the  ex-| 
periments  referred  to,  and  arrived  at  similar  conclusions  as  1 

'  The  experiments  of  Vulpian  seem  to  prove  that  the  internal  portion  of  the  anterior >j 
column  does  exhibit  a  trace  of  excitability  in  the  normal  state.  j 

^  The  experiments  of  Brown-S6quard  seem  to  warrant  this  conclusion.  Very  little  ! 
gray  matter  may,  therefore,  suffice  to  convey  sensory  impressions  (chiefly  those  of  pain  « 
and  temperature).  ] 


TROPHIC  FUNCTIONS  OF  THE  CORD.  577 

Ills  predecessor,  viz. ,  that  such  sensations  as  can  be  tested  in 
animals  pass  up  the  lateral  columns  of  the  cord  in  the  dorsal 
region.  If  this  view  be  true  of  man,  as  well  as  of  animals,  it 
must  follow  that  a  portion  of  the  lateral  column,  which  is 
not  occupied  by  the  ''crossed  pyramidal  tract,"  must  be  asso- 
ciated with  sensory  conduction.  Each  lateral  column  appears 
from  these  experiments  to  contain  sensory  fibers  from  both 
legs.  It  has  not  yet  been  demonstrated  that  the  lateral  col- 
umns conduct  sensory  impulses  in  man. 

In  addition  to  its  other  functions,  the  gray  matter  of  the 
cord  seems  to  exert  a  controlling  influence  upon  the  nutrition 
of  muscles  and  other  tissues.  When  the  anterior  portion  be- 
comes tjie  seat  of  disease,  the  muscles  often  undergo  atro- 
phy, and  occasionally  joint-diseases  develop.  This  so-called 
"^  trophic  function^  "^  is  not  yet  thoroughly  understood. 

Clinical  facts  seem  to  prove  that  the  muscles,  and  possibly 
the  bones  and  joints  also,  are  controlled,  in  respect  to  their 
nutrition,  by  the  anterior  roots  of  the  spinal  nerves,  while  the 
nutrition  of  the  skin  seems  to  be  controlled  by  the  posterior 
roots. 

When  the  nutrition  of  a  nerve  is  impaired,  its  faradaic  ex- 
citability is  proportionately  decreased.  A  stronger  current  of 
electricity  is  then  required  to  create  a  response  in  the  form  of 
muscular  contraction.  There  exists  clinical  and  pathological 
as  well  as  experimental  evidence  to  sustain  the  view  that  the 
motor  nerve  cells  in  the  anterior  horns  of  the  cord  are  the 
so-called  "trophic  centers"  for  the  motor  fibers  of  the  an- 
terior roots  and  possibly  also  for  the  bones  and  joints.  In 
fact,  the  motor  nerves  may  he  considered  as  simple  prolonga- 
tions of  the  processes  of  these  cells  to  the  muscles.  On  the 
other  hand,  the  ganglion  of  the  posterior  root  seems  to  be 
the  trophic  center  for  the  sensory  fibers  of  each  spinal  seg- 
ment ;  since  it  has  been  proven  by  Waller  that  these  fibers 
degenerate  when  the  posterior  root  is  severed  outside  of  the 
ganglion.  The  pyramidal  motor  tracts  of  the  cord  have 
their  trophic  centers  apparently  in  the  cells  of  the  cerebral 
cortex. 


578  THE  SPINAL   CORD. 

The  gray  matter  of  the  cord  is  known  to  embrace  several  i 
special  centers,  the  two  most  important  of  which  are  the  cilio-  {| 
spinal  center  and  the  genito-urinary  center.  The  former  of  jj 
these  is  situated  in  the  cervical  Tegion,  at  its  lowest  part/  and  i 
exerts  an  influence  upon  the  pupil  of  the  eye  and  the  skin  of  i 
the  face  and  neck;  hence  it  is  often  a  valuable  guide  to  | 
determine  the  height  of  a  lesion  in  the  spinal  cord,  since  the  \ 
pupils  show  changes  when  it  is  involved  that  are  of  value  to  | 
the  diagnostician.  The  latter  center  (genito-urinary)  is  situ-  ; 
ated  in  the  dorso -lumbar  portion  of  the  cord,  and  often  : 
creates  symptoms,  when  disease  of  the  cord  exists,  referable  \ 
to  the  bladder  and  genital  organs.  Certain  smaller  centers,  \ 
having  a  vaso-motor  function,  are  described  by  some  authors  ;  1 
but  their  situation  and  special  functions  are  either  unknown  \ 
or  of  little  practical  utility  in  diagnosis.  The  physiological  j 
centers  of  the  cord  are,  as  yet,  a  matter  deserving  further  in-  f 
vestigation  before  any  positive  statements  can  be  made  con-  j 
cerning  them.  « 

In  certain  forms  of  spinal  disease,  evidences  that  the  sym-  ! 
pathetic  or  vaso-motor  system  is  involved  appear  in  altera- 
tions of  the  temperature  and  vascularity  of  the  limbs,  and  j 
sweating  of  regions  supplied  by  nerves  that  are  associated  '. 
with  the  diseased  area  or  impaired  by  the  lesion.  Hyper- • 
pyrexia  is  common  with  lesions  of  the  cervical  enlargement;  ^ 
of  the  cord,  if  the  lesion  be  of  a  sudden  character.  If  one  ^ 
lateral  half  of  the  cord  is  affected  by  a  localized  lesion,  it  is  * 
not  uncommon  to  meet  with  unilateral  sweating  and  flushing.  ; 
This  can  be  attributed  alone  to  the  fact  that  vaso-motor  fibers  i 
either  pass  through  or  arise  within  the  substance  of  the  cord.  \ 

*  The  researches  of  Waller,  Budge,  and  Brown-S6quard  would  indicate  the  limits  of  -% 
this  center  between  the  fifth  cervical  and  second  dorsal  vertebrae.  It  exists  in  each  lat-  ; 
eral  half  of  the  cord.  It  presides  over  the  vaso-motor  nerves  for  the  vessels  of  the  cor-  '} 
responding  eye  and  side  of  the  face  and  neck.  Vulpian  places  its  limits  as  low  as  the  \ 
fourth  dorsal,  and  Claude  Bernard  as  low  as  the  seventh  dorsal,  while  Schiff  carries  its  \ 
limits  as  high  as  the  medulla  itself.  J 

Vuipian's  conclusions  indicate  the  grai/  matter  of  the  cord  as  positively  incapable  of  \ 
exdtahilily  ;  but  he  attributes  slight  excitability  to  the  anterior  fasciculi  of  the  cord  and  \ 
great  excitability  to  the  posterior  columns.  In  these  deductions,  he  differs  somewhat  ' 
from  the  results  of  Chauveau,  made,  in  1861,  upon  the  domestic  animals.  ^ 

*i 


COORDINATION  OF  MOVEMENT.  6Y9 

Furthermore,  stimulation  of  the  cutaneous  surface  is  capable 
in  health  of  creating  a  dilatation  of  the  pupil,  but  this  effect 
is  not  usually  observed  when  a  spinal  lesion  has  involved  the 
cilio  spinal  center  (Erb). 

In  the  posterior  column  of  the  cord,  comprising  the  col- 
umns of  Goll  and  of  Burdach,  there  exists  a  certain  amount 
of  wliite  substance^  one  of  whose  functions  seems  to  be  to  act 
as  commissural  fibers  between  certain  portions  of  the  spinal 
cord.  This  portion  appears  to  bear  some  important  relation 
to  the  power  of  coordination '  of  muscular  movement,  since 
disease  of  this  region  of  the  cord  is  followed  or  accompanied 
by  disorders  of  motion,  called  ataxic  symptoms,  which  are  not 
due  to  paralysis. 

Like  the  cerebrum,  the  spinal  cord  has  the  inherent  power 
of  presiding  over  certain  muscular  acts.  It  is  now  quite  con- 
clusively proved  that  the  automatic  acts  of  walking,  standing, 
swimming,  and,  to  some  extent,  playing  upon  musical  instru- 
ments, dressing,  etc.,  are  largely  controlled  by  the  spinal  cord 
alone.  It  is  unquestioned  that  certain  of  these  acts  can  be 
made  so  mechanical  that  the  spinal  cord  is  slowly  and  pain- 
fully educated  to  perform  them  without  any  aid  from  the 
cerebrum.  It  is  not  probable,  however,  that  the  gray  matter 
of  the  cord  has  anything  to  do  with  the  attribute  of  con- 
sciousness. 

Fibers  of  the  Spinal  Cord. — There  are  probably  three 
distinct  varieties  of  fibers  within  the  substance  of  the  spinal 
cord,  exclusive  of  vaso-motor  filaments,  viz.,  motor  fibers,  sen- 
sory fibers,  and  commissural  fibers.  Each  of  these  has  been 
already  mentioned,  and  some  points  of  general  interest  per- 
taining to  their  situation  and  function  have  been  given ;  but 
there  are  some  points  which  must  be  described  more  fully 
before  we  are  able  to  intelligently  discuss  the  symptoms  of 
spinal  affections. 

The  motor  fibers  are  continued  into  the  anterior  roots  of 
the  spinal  nerves  after  joining  with  the  motor  cells  of  the 

^  The  cerebellum  has  also  much  to  do  with  the  coordination  of  muscular  move- 
ments. 


680  THE  SPINAL   CORD. 

anterior  horn.  They  escape  from  the  substance  of  the  cord 
in  the  region  of  the  anterior  horns  of  gray  matter.  If  we 
trace  them  from  the  nerve  trunk  toward  the  center  of  the 
cord,  we  shall  find  that  they  penetrate  the  anterior  horns,  and 
are  in  immediate  connection  with  the  prolongations  of  the 
motor  cells  of  that  portion  of  the  gray  matter.  Certain  motor 
fibers  can  be  also  traced  toward  the  brain  as  two  distinct 
tracts  passing  upward  in  the  anterior  and  lateral  columns  of 
the  white  substance  of  each  lateral  half  of  the  cord.  Pro- 
longations of  the  motor  cells  of  the  gray  matter  are  now 
known  to  be  associated  with  these  motor  tracts,  that  ascend 
to  the  brain  in  the  white  substance.  Now,  this  connection 
between  the  motor  fibers  of  the  spinal  nerve  roots  and  the 
nerve  cells,  and  the  second  connection  of  the  same  cells  with 
fibers  going  to  the  brain,  would  seem  to  suggest  the  hypoth- 
esis that  the  motor  impulses  are  sent  first  from  the  brain  to 
the  cells  of  the  cord,  and  from  them,  through  the  spinal 
nerves,  to  the  muscles.  When  the  cord  is  taught  to  perform 
certain  automatic  acts  without  the  intervention  of  cerebral 
action,  these  cells  themselves  are  the  exciting  organs  of  the 
motor  impulses  (since  they  are  the  elements  which  are  most 
probably  concerned  in  the  reflex  movements  of  the  spinal 
cord).  We  know  that  the  legs  of  a  frog  can  be  made  to  per- 
form muscular  movements  after  the  head  has  been  taken  off, 
by  simply  stimulating  the  sensory  nerves ;  and  we  see  the 
same  reflex  movements  occurring  in  paralyzed  limbs,  which 
are  out  of  the  voluntary  control  of  the  brain.  To  explain 
these  phenomena,  we  are  forced  to  believe  that  the  motor 
cells  of  the  cord  are  capable,  when  called  upon,  of  performing 
many  muscular  acts,  some  of  which  would  seem  too  complex 
for  spinal  control  without  cerebral  assistance,  such,  for  ex- 
ample, as  walking,  swimming,  playing  upon  musical  instru- 
ments, etc.  By  referring  to  the  cut,*  where  a  multipolar  spinal 
cell  is  magnified,  and  also  to  Fig.  178,  you  will  easily  under- 
stand how  these  various  poles  can  be  connected  with  one  motor, 
and  probably,  also,  with  many  sensory  fibers  ;  hence,  it  can  be 

*  See  Fig.  177  of  this  volume. 


MOTOR  APPARATUS  OF  THE  CORD. 


581 


Fig.  177. — Multipolar  nerve  cell  from  the  anterior  cornu  of  the  spinal  cord  of  the  ox; 
magnified  200  diameters.     (Deiters.) 

a,  axis-cylinder  prolongation,  or  the  motor  process ;  6,  6,  6,  6,  6,  6,  branching  prolonga- 
tions, which  are  probably  not  motor  in  function. 


582  THE  SPINAL   CORD. 

seen  that  the  cell  may  receive  certain  sensory  impressions 
from  some  poles  and  send  out  certain  motor  impulses  to  the 
muscles  by  means  of  its  axis-cylinder  process,  thus  account- 
ing for  the  muscular  movements  which  follow  the  irritation  of 
sensory  nerves. 

The  sensory  fibers  enter  the  cord  by  means  of  the  pos- 
terior roots  of  the  spinal  nerves.  They  are  intimately  con- 
nected at  first  with  the  posterior  horns  of  the  gray  matter, 
although  some  of  them  appear  to  avoid  the  horn  and  to  enter 
Burdach's  column  directly.  They  probably  ascend  and  de- 
scend in  the  columns  of  Burdach  for  a  certain  distance,  and 
then  decussate.  The  decussation  of  the  sensory  fibers  is 
accomplished  either  by  the  passing  of  the  fibers  themselves 
to  the  opposite  side  of  the  cord,  or  by  the  prolongation  of 
some  of  the  poles  of  the  spinal  cells  into  the  gray  matter  of  | 
the  opposite  side.  The  decussation  probably  takes  place 
exclusively  in  the  commissural  gray  matter.  While  this 
decussation  seems  positively  proven  by  all  physiological 
experiment,  little  of  a  positive  character  has  as  yet  been 
shown  by  actual  anatomical  demonstration.  The  nerves  that 
carry  sensations  of  pain  are  in  communication  with  the  cor- 
tex of  the  encephalon,  probably,  by  means  of  the  gray  matter 
of  the  spinal  cord,  which  acts  as  a  conducting  medium  for 
the  centripetal  impulses.  As  before  mentioned,  the  gray 
matter  which  surrounds  the  central  canal  of  the  spinal  cord 
seems  to  be  an  important  channel  for  the  transmission  of 
painful  sensations  and  temperature  impressions  from  the 
trunk  and  the  extremities  to  the  brain.  Thus  we  apparently 
have  in  thie  spinal  cord  a  conducting  shaft,  to  which  certain 
sensory  nerves  become  joined,  and  which  conducts  the  im- 
pressions received  through  them  to  the  ganglia  or  the  cortex 
of  the  encephalon.  It  is  evident,  therefore,  that  some  of  the 
sensory  nerves  are  not  continuous  fibers  between  the  brain 
and  the  parts  to  which  they  are  distributed ;  in  which  respect 
they  resemble  the  motor  nerves,  whose  fibers  are  indirectly 
carried  to  the  brain — the  motor  cells  of  the  cord  being  proba- 
bly interposed. 


SENSORY  TRACTS  OF  THE  CORD. 


683 


The  fibers  that  conyej  painful  sensations  appear  to  trav- 
erse the  posterior  horns  of  the  spinal  gray  matter,  without 
passing  into  the  column  of  Burdach. 

The  tactile  sense  seems  to  be  presided  over  by  fibers  that 
pass  from  the  posterior  nerve  roots  directly  into  Burdach's 
column.     They  probably  do  not  all  decussate.     Some  cross 


Fig.  1*78. —  Transverse  section  of  the  graif  substance  of  the  anterior  cornua  of  the  spinal 
cord  of  the  oz^  treated  with  nitrate  of  silver.      (Grandry.) 


over  at  once,  and  others  reach  the  opposite  side  after  ascend- 
ing for  a  greater  or  less  distance  in  Burdach's  column  of  the 
same  side. 

Some  sensory  impressions  reach  the  brain,  in  animals  at 
least,  by  means  of  the  lateral  columns  of  the  cord.  These  are 
not,  as  yet,  well  understood. 

Finally,  the  fibers  that  convey  the  impressions  known  as 
the  "muscular  sense''''  are  now  believed  to  reach  the  cord  by 
means  of  the  posterior  roots  of  the  spinal  nerves  and  to  pass 
upward  in  the  posterior  portion  of  the  spinal  cord  without 


584  THE  SPINAL   CORD. 


decussation.  By  means  of  these  fibers  we  are  enabled  to  esti-  ; 
mate  the  amount  of  muscular  force  required  to  perform  spe-  j 
cial  acts,  as  in  discriminating  between  weights,  raising  a  limb  ] 
to  definite  heights  with  the  eyes  closed,  throwing  a  ball  for 
definite  distances,  etc.  It  is  thought  that  the  fibers,  con-  ; 
nected  with  this  sense,  do  not  decussate. 

We  are  forced  to  admit  that  our  knowledge  of  the  exact  jj 
seat  and  function  of  the  various  paths  of  sensory  conduction  | 
is  still  somewhat  speculative.  1 

The  clinical  association  of  ataxia  of  opposed  limbs  with  a  / 
lesion  of  the  flZlet  and  the  inter  olivary  trdct  has  been  ob-  jl 
served  by  Kahler,  Meyer,  Senator,  and  Spitzka.  These  ob-  \ 
servations  have  been  collected  and  contrasted  wdth  one  another  j 
by  Starr.  The  latter  author  is  led  to  the  conclusion  that  the  jj 
fibers  which  are  functionally  related  to  the  muscular  sense  j| 
are  the  only  ones  which  decussate  within  the  medulla,  and  f 
that  they  do  so  because  they  fail  to  decussate  within  the  t 
cord.  I 

It  seems  to  be  well  established  that  sensory  impressions  of  ! 
aU  kinds  pass  from  the  posterior  nerve  roots  to  the  opposite  | 
half  of  the  cord,  at  least  partially  if  not  completely.  The  1 
researches  of  Kobner  appear  to  demonstrate  that  the  fibers  '\ 
which  convey  the  sensations  of  pain  and  temperature  decus-  ' 
sate  at  a  lower  level  after  entering  the  cord  than  do  the  fibers  ^ 
which  convey  tactile  sensations. 

The  commissural  fibers  of  the  cord  probably  exist  in  the 
white  substance  of  the  posterior  columns.'    The  spinal  cord 
may  properly  be  considered  as  a  mass  of  superimposed  seg- 
ments ;  hence,  a  great  necessity  exists  for  certain  fibers  which  ] 
shall  tend  to  unite  the  different  parts,  and  thus  conduce  to   ] 
the  perfect  harmony  of  action  of  the  whole.     It  is  not  possi-   j 
ble  to  demonstrate  the  existence  and  exact  situation  of  such  | 
fibers,  but  all  physiological  and  pathological  deductions  seem   j 
to  sustain  this  hypothesis.     These  fibers  have,  probably,  a    ' 

'  A.  Flint,  Jr.,  op  cit.  The  experiments  made  to  prove  this  point  may  be  found  in  jJ 
almost  any  of  the  later  treatises  on  physiology.  Some  authors  believe  that  commissoral  |g 
fibers  exist  also  in  the  antero-lateral  columns.  ft 


GENERAL  ARRANGEMENT  OF  SPINAL   TRACTS, 


585 


most  important  influence  in  the  proper  coordination  of  mus- 
cular movement. 

The  diagram  (Fig.  179)  illustrates,  in  a  very  simple  way, 
the  general  course  of  the  motor  and  sensory  paths  of  the  spi- 


i^iie'     6  5243     1' 


LOWER  LIMIT  OF 
MEDULLA 


Fig.  179. — A  diagram  designed  by  the  author  to  show  the  course  of  the  fhers  which 
compose  the  spinal  cord. 

1, 1',  direct  pyramidal  bundles ;  2,  2',  crossed  pyramidal  bundles,  decussating  in  medulla; 
3,  8',  direct  cerebellar  fibers ;  4,  4',  fibers  related  to  "  muscular  sense,"  decussating 
in  medulla ;  5,  5',  and  6,  6',  fibers  related  to  the  appreciation  of  touch,  pain,  and 
temperature.  The  motor  bundles  have  a  dot  upon  them  to  represent  the  motor  cells 
of  the  cord  (anterior  horn).  Note  that  the  motor  fibers  escape  from  the  anterior 
nerve  root  (a.  r.),  and  that  the  sensory  bundles  enter  at  the  posterior  nerve  root  {p.  r.\ 
which  have  a  ganglion  {jg)  upon  them. 


nal  cord.  It  shows  that  hotJi  the  sensory  and  motor  fibers  de- 
cussate ;  but  that  the  motor  fibers  and  those  associated  with 
the  muscular  sense  cross  in  the  medulla  oblongata  only,  while 
the  sensory  fibers  cross  soon  after  they  enter  the  spinal  cord, 


586 


THE  SPINAL    CORD. 


I 


when  they  join  with  the  gray  matter,  and  use  that  as  a  means 
of  transmitting  their  sensory  impressions  to  the  brain.  The 
diagram  also  shows  that  the  sensory  fibers  spring  from  the 
posterior  roots  of  the  spinal  nerves,  since  the  ganglionic  en- 
largement is  depicted  upon  the  sensory  fibers. 

Now,  it  is  easy  to  understand,  by  means  of  this  diagram, 
why  any  lesion  above  the  medulla  oblongata  must  produce 
most  of  its  symptoms  on  the  side  of  the  body  opposite  to 
that  of  the  exciting  cause,  since  the  vast  majority  of  the 
motor  and  sensory  fibers  both  decussate  below  that  point; 
while  it  also  shows  that  any  lesion  below  the  medulla  oblon- 
gata must  produce  motor  symptoms  and  a  loss  of  muscular 
sense  upon  the  same  side  as  the  lesion.     In  all  spinal  lesions, 


Fig.  180. — Nei've  cell  from  the  ferruginous  substance  which  forms  the  floor  of  the 
rliomboidal  sinus  in  man  ;   magnified  350  diameters.     (Kolliker.) 

causing  motor  paralysis,  the  body  is  affected  below  the  point 
of  disease,  because  the  conducting  fibers  to  the  brain  are  cut 
off;  while,  in  lesions  of  the  posterior  portion  of  the  spinal 
cord,  the  nerves  of  that  region  may  be  rendered  incapable  of 


if 


COMMISSURAL  AND    VASO-MOTOR  FIBERS.  587 

action,  but  the  parts  below  may  be  still  capable  of  perceiving 
sensory  impressions,  especially  those  of  pain  and  temperature, 
provided  that  the  gray  matter  is  left  intact,  or  sufficient  of  it 
remains  to  act  as  a  conducting  medium  to  the  brain. 

The  commissural  fibers  of  the  spinal  cord  are  not  depicted 
in  this  diagram  (Pig.  179),  since  little  is  positively  known  as 
to  their  exact  situation  or  function.  As  they  are  probably 
conhned  largely  to  the  posterior  half  of  the  spinal  cord,  and 
as  they  are  also  probably  intimately  associated  with  the  coor- 
dination of  movement,  it  is  not  difficult  to  see  why  the  symp- 
toms of  ancestliesia  and  ataxia  should  march  hand  in  hand, 
when  the  spinal  cord  is  diseased  in  this  region  ;  and  why  neu- 
ralgic pains  should  be  created  by  the  irritation  to  the  sensory 
nerves,  rather  than  muscular  spasm,  which  would  only  exist 
if  the  motor  nerves  were  irritated.  This  general  subject  will, 
however,  be  more  fully  discussed  in  connection  with  the  clin- 
ical aspects  of  locomotor  ataxia  and  degeneration  of  the  pos- 
terior portion  of  the  cord  (the  columns  of  Goll  and  Burdach). 

The  vaso-motor  paths  within  the  spinal  cord  have  been 
the  subject  of  experimental  investigation  down  to  the  pres- 
ent time.  We  know  that,  if  the  spinal  cord  be  cut  at  any 
point,  the  arteries  below  the  point  of  section  undergo  marked 
dilatation,  and  that  irritation  of  the  cord  creates  a  contraction 
of  the  arteries  below  the  seat  of  irritation.  We  are,  there- 
fore, justified  in  drawing  the  conclusion  that  the  vaso-motor 
paths  carry  centrifugal  impulses. 

As  regards  their  situation  within  the  cord,  it  seems  proba- 
ble that  the  lateral  columns  and  the  gray  matter  are  traversed 
by  the  vaso-motor  paths.  Whether  they  decussate  or  not  is 
an  open  question.  Schiff  believes  that  it  can  be  proved  that 
the  vaso-motor  nerves  for  the  vessels  of  the  trunk  and  thigh 
decussate,  but  Yon  Bezold  positively  denies  the  statement. 
One  remarkable  fact,  viz.,  that  the  vessels  after  becoming 
paralyzed  from  section  of  the  cord  soon  regain  their  natural 
condition,  seems  to  demonstrate  that  the  cord  contains  vaso- 
motor centers  throughout  its  entire  length,  and  that  the  vaso- 
motor tracts  are  not  entirely  dependent  upon  the  chief  center 


588 


TEE  SPINAL    CORD. 


within  the  substance  of  the  medulla  in  the  performance  of 
their  function.  It  seems  probable  that  these  vaso-motor  cen- 
ters are  to  be  found  in  the  anterior  part  of  the  spinal  gray- 
matter. 

The  vaso-motor  nerves  leave  the  cord  by  the  anterior  nerve 
roots.  Those  that  are  connected  with  the  vessels  of  the  head 
come  from  the  cervical  portion  of  the  cord ;  those  for  the 
upper  extremities,  from  the  upper  dorsal  region ;  those  for 
the  pelvis  and  lower  limbs,  from  the  lower  dorsal  and  lumbar 
segments  of  the  cord.  The  splanchnic  nerves  apparently  con- 
vey the  vaso-motor  nerves  to  the  viscera  of  the  abdomen,  and 
the  lumbar  nerves  perform  a  similar  function  for  the  genito- 
urinary apparatus. 

In  concluding  his  exhaustive  article  upon  the  localization 
of  the  functions  of  the  spinal  cord,  M.  A.  Starr'  gives  two 
tables  as  a  summary  of  the  results  of  the  combined  research 
in  that  direction  to  date.  I  deem  them  so  valuable  and  ex- 
plicit that  I  take  the  liberty  of  quoting  them  in  full  (pages 
588,  589,  590) : 

LOCALIZATION  OF  FUNCTIONS  IN  THE  VARIOUS  SEGMENTS  OF  THE 
SPINAL  CORD.      (after  STARR.) 


Segment 

Muscles. 

Beflexes. 

Sensation. 

2d-8d  C. 

Sterno-mast.     Trapezius. 

Neck    and    back    of 

Scaleni  and  muse,  of  neck. 

head. 

Diaphragm. 

Hypochondrium  (?) 

4th  C. 

Diaphragm. 

Dilatation  of  pupil. 

Neck. 

Supra-  and  Infra-Spinatus 

on  irritation  of  neck. 

Upper  shoulder. 

Deltoid. 

4th-7th  C. 

Outer  arm. 

Biceps,  and  Coraco-Brach. 

Supinator  Longus. 

Rhomboid. 

6th  C. 

Deep  muscles  of  shoulder- 

Scapular. 

Back  of  shoulder  and 

blade. 

5th  C.-lst  D. 

arm. 

Deltoid. 

Outer  side  of  arm  and 
forearm. 

Biceps  and  Coraco-Brach. 

Ant.  upper  two  thirds 
of  arm. 

Supinator  Longus. 

Pectorales. 

Serratus  Magnus. 

Triceps. 

Elbow  tendon. 

Rhomboid.     Teres  minor. 

5th-6th  C. 

American  Journal  of  Neurology  and  Psychiatry,"  August  and  November,  1884. 


-il 


SPINAL  LOCALIZATION  {STARR'S  TABLE). 


589 


Segment 

Muscles. 

Keflexes. 

Sensation. 

6th  C. 

Biceps  Brach.  Antic. 

Outer  side  of  arm  and 
forearm. 

Peetorales. 

Inner  and  front  of 
forearm. 

Serratus  Magnus. 

Triceps. 

Extensors    of    wrist    and 

Wrist  tendons. 

fingers. 

Flexors  of  wrist. 

Wrist  tendons. 

Pronators.    Supinator  Bre- 

6th-8th  C. 

7th  C. 

vis. 
Triceps  long  head. 

Extensors  of  wrist  and  fin- 

Inner and  back  of 
arm  and  forearm. 

gers. 
Flexors  of   wrist   and  fin- 

Palmar. 

Radial  distribution  in 

gers. 

m-sth  C. 

the  hand. 

Pronators  of  wrist. 

Subscapular. 

Latissimus  Dorsi. 

■ 

Teres  major. 

8th  C. 

Extensors  of  thumb. 

Forearm     and    hand, 

Flexors  of  wrist  and  fin- 

median and    ulnar 

gers. 

distribution. 

Intrinsic  muscles  of  hand. 

IstD. 

Extensors  of  thumb. 

Ulnar  distribution  to 

Intrinsic  muscles  of  hand. 

hand,  little  finger. 

Thenar     and    hypothenar 

eminences. 

2d-12th  D. 

Muscles  of  back  and  abdo- 

fEas,}8«»-ifcis 

Skin  of  back  and  ab- 

men. 

domen,  and  over  up- 

Erector   Spinae   mus- 
cles. 
Hypochondrium  (?) 

per  gluteal  region. 

1st  L. 

Ilio-psoas. 

Cremasteric. 

Skin  over  groin  and 

Sartorius. 

lst-3d  L. 

front  of  scrotum. 

2dL. 

Ilio-psoas. 

Patellar  tendon. 

Outer  side  of  thigh. 

Sartorius, 

2d-4th  L. 

Flexors   of  knee,    Remak 

Bladder  and  sexual 

(?) 

centers. 
2d-4th  L. 

3dL. 

Quadriceps  femoris. 
Adductores  femoris. 

Front  of  thigh. 

4th  L. 

Abductores  femoris. 

Rectal  center. 

Inner  side    of    thigh 

Extensores  femoris. 

4th  L.-2d  S. 

and  leg  to  ankle. 

Tibialis  Anticus. 

Gluteal. 

Peroneus  Longus. 

4th-5th  L. 

Flexors  of  knee,    Ferrier 

(?) 
Outward  rotators  of  thigh. 

5th  L. 

Lower  part  of  gluteal 

Flexors  of  knee  (Ferrier). 

region. 

Flexors  and  Extensors  of 

Back  of  thigh. 

toes. 

Leg  and    foot,   outer 

Peronei. 

part. 

Muscles  of  calf  of  leg. 

IstS. 

Muscles  of  calf  of  leg. 

Foot  clonus. 

Leg  and  foot  except 

Long  flexor  of  great  toe. 

Achilles  tendon. 

inner  part. 

Intrinsic  muscles  of  foot. 

Plantar. 

2dS. 

Intrinsic  muscles  of  foot. 

Plantar. 

Perineum.     Anus. 

40 


590 


THE  SPINAL   CORD. 


LOCALIZATIONS   OF  FUNCTION'S   IN  THE  VAKIOUS   PARTS  OF   ONE  SEG- 
MENT OF  THE   SPINAL   CORD.       (AFTER   STARR.) 


I.  Gray  Matter. 


1.  Anterior  horn. 


2.  Central  portion. 


3.  Posterior  horn. 


Inner  group  of  cells. 
Lateral  groups  of  cells 

in  enlargements. 
Median  group  of  cells. 
Central  group  of  cells 

in  enlargements. 


Fundamental  motions  common  to  all 
vertebrates,  e.  g.,  flexion  and  exten- 
sion of  limbs. 

Accessory  motions  peculiar  to  man, 
e.  g.,  fine  movements  of  the 
hands. 


Motor  cells  of  undetermined  function  in  other  regions. 

Trophic  centers  for  muscles  and  motor  nerves. 

The  motor  part  of  reflex  and  automatic  centers. 

Ant.  part,  trophic  centers  for  bones. 

Post.  part,  trophic  centers  for  skin,  nails,  joints,  bladder,  vaso- 
motor centers. 

Complex  automatic  centers  and  their  association  fibers. 

Basal  part ;  trophic  centers  for  centripetal  tracts. 

Tract  for  transmission  of  sensations  of  pain  and  temperature 
from  the  parts  below. 

Vesicular  column  of  cells;  vegetative  reflex  centers  (?). 

Posterior  group  of  cells ;  sensations  of  all  kinds. 

The  sensory  part  of  reflex  and  automatic  acts. 

II.  White  Matter. 

1.  Ant.  median  column.  . .  Motor  tract  from  like-named  hsmisphere  of  brain. 
Association  fibers  between  segments  of  the  cord. 
Motor  nerve  fibers  between  cells  and  roots. 
Association  fibers  between  segments  of  cord. 
Vaso-motor  tracts  (?). 


2.  Anterior  column. 
8,  Lateral  column. 


4.  Postero-lateral  or 

pyramidal  column. 

5.  External    lateral   or 

direct     cerebellar 
column. 


Motor  tract  from  opposite  hemisphere  of  brain. 
Vegetative  tract  (?), 


f  Sensory  nerve  fibers  between  roots   and  cells,  except  thosei 
6.  Post,    external    col-  forming  sensory  arc  of  skin  reflex. 

umn  or  column  of  \  Association  fibers  between  segments  of  the  cord. 

Burdach.  Sensory  tract  for  touch  and  muscular  sense  from  the  upper 

[      dorsal  and  cervical  regions  upward. 

[  Sensory  tract  for  touch  and  muscular  sense  from  the  lower 
J  dorsal,  lumbar,  and  sacral  regions.  The  tracts  from  the 
I  distribution  of  sciatic  nerves  lying  in  the  posterior  median 
[^      portion  of  the  column. 


7.  Posterior    median 
column  or  column 
of  Goll. 


THE   SPINAL  CORD   AS  A   NERVE   CENTER. 

If  the  cord  be  separated  from  the  brain  in  a  living  animaly 
it  may  still  act  as  a  nerve  center,  independently  of  the  brain 
but,  since  the  spinal  cord  is  then  in  communication  only  witb^ 
the  nerves  which  arise  from  it,  it  can  only  affect  the  spinjiii 
nerves,  and  not  those  of  cranial  origin.  This  automatic  actioEl 
of  the  spinal  cord  is  of  a  purely  reflex  type  under  such  con-i 
ditions.  It  can  be  demonstrated  by  exciting  some  one  of  thei 
sensory  nerves,  when  a  muscular  response  will  be  created 
hence  the  term  '^excito-motor"  is  often  applied  to  this  typi 


SPINAL  REFLEXES  AND  AUTOMATISM.  591 

>f  manifestation,  whether  occurring  during  life,  as  the  result 
)f  disease  or  peripheral  irritation,  or  after  death,  as  in  the 
physiological  experiment  alluded  to.     There  are  certain  acts 
vhich  are  constantly  occurring  in  the  body,  such  as  the  move- 
nents  of  the  pupils,  of  the  intestinal  canal,  of  respiration, 
'tc,  which  are  properly  classed  as  reflex  in  type,  but  which 
ire  not  dependent  upon  the  spinal  cord  alone.     In  fact,  all 
notor  acts  are  classed  as  belonging  to  the  reflex  type,  which 
ire  the  direct  result  of  some  form  of  sensory  irritation  ;  but 
he  term  is  generally  used,  in  discussing  the  spinal  cord,  in 
ts  most  restricted  sense,  where  the  muscular  act  is  purely 
nvoluntary,  the  result  of  some  direct  irritation  of  a  sensory 
pinal  nerve,  and  confined  to  regions  of  the  body  over  which 
he  spinal  cord  exerts  a  direct  influence.     Thus,  we  often  see 
he  muscles  of  a  paralyzed  limb  suddenly  thrown  into  invol- 
mtary  and  unexpected  contraction,  when  a  draught  of  cold 
dr  strikes  the  skin,  or  when  any  form  of  irritation  is  directly 
ipplied  to  it ;  while  such  spasms  are  common  in  certain  forms 
)f  spinal  disease  which  tend  to  create  irritation  of  the  spinal 
,  ;.tructures,  irrespective  of  any  apparent  exciting  cause. 
I     We  have  already  referred  to  certain  naso-motor  centers 
'  HrMch  exist  in  the  substance  of  the  spinal  cord,  the  two  most 
mportant  of  which  are  the  cilio-spinal  center  and  the  center 
'  tor  the  geni to-urinary  apparatus.    The  former  of  these  is  situ- 
\  ited  in  the  cervical  region,  and  exerts  some  marked  effects 
«  ipon  the  eye,  face,  and  neck ;  while  the  latter  is  situated  in 
he  dorso-lumbar  region  of  the  cord.     If  the  medulla  oblon- 
gata be  considered  as  the  upper  expansion  of  the  spinal  cord 
il  and  there  are  many  anatomical  reasons  for  thus  considering 
J,  jt),  all  the  centers  mentioned  as  situated  in  that  ganglion  may 
jl(j)e  included  among  the  spinal  centers  of  automatic  action. 
I  ^ome  authors  have  gone  so  far  as  to  locate  in  the  spinal  cord 
(!  pertain  centers  which  preside  over  the  acts  of  micturition, 
y  iefecation,  parturition,  erection,  etc.,  and  experiment  seems 
0  give  reason  to  hope  that  a  more  definite  ground  will  be 
^  ifforded  for  such  belief,  although  but  little  of  a  positive  char- 
icter  can  as  yet  be  given  in  regard  to  their  situation. 


592  THE  SPINAL   CORD. 

The  vaso-motor  nerves  for  the  trunk,   extremities,   and 
abdominal  viscera  probably  originate  in  different  ways  (se( 
researches  of  Yulpian,  Schiff,  Cyon,  Claude  Bernard,  and  the 
later  researches  of  Dastre,  Laffont,  and  Morat).     According 
to  the  monograph  of  Gray,'  those  for  the  upper  extremities 
are  derived  (1)  from  the  inferior  cervical  and  superior  thoJI 
racic  ganglion,  uniting  at  the  brachial  plexus,  close  to  thejj 
first  rib;   (2)  from  the  nerve  roots  of  the  brachial  plexus;' 
(3)  from  the  thoracic  cord  of  the  sympathetic,  and  from  the, I 
nerve  roots  of  the  third,  fourth,  fifth,  sixth,  and  seventh* 
dorsal  nerves,  principally  from  the  third  and  seventh.  j' 

Those  for  the  lower  extremities  proceed  (1)  from  the  spinal  * 
cord  with  the  sciatic  and  crural  nerves  ;  (2)  from  the  abdomi-  j 
nal  cord  of  the  sympathetic.  I 

The  abdominal  viscera  are  supplied  with  fibers  arising^ 
from  a  considerable  length  of  the  dorsal  and  lumbar  cord,  and'- 
running  within  the  sheath  of  the  splanchnic  nerve,  as  well  aa'i 
by  fibers  from  the  abdominal  cord  of  the  sympathetic.  The 
vaso-motor  nerves  of  the  head  and  face  take  their  origin  from  i 
what  is  known  as  the  "  cilio-spinal  center,"  and  when  this  i 
center  is  destroyed  there  ensues  a  marked  dilatation  of  the ! 
capillaries  of  the  head  and  face. 

It  has  been  claimed  that  the  spinal  nerves  exercise  a  i 
tonic  action  over  the  muscles  which  move  the  different  pop*  I 
tions  of  the  skeleton,  in  the  same  way  as  the  vaso-motor  i 
nerves  exercise  such  a  power  over  the  muscular  fibers  in  the 
coats  of  the  blood-vessels.  Certain  experimental  phenomena  . 
— chiefly  the  gaping  of  a  wound  in  muscular  tissue — have  \ 
been  advanced  to  sustain  the  theory.  This  view  is  not,  ^ 
however,  fully  sustained  by  all  the  facts,"  and  is  not  gener-  * 
ally  accepted  by  the  leading  physiologists.  \ 

From  a  late  lecture,'  I  quote  the  following  extract :  "  We< 
have  come  to  learn  that  each  group  of  cells — perhaps  each(( 
cell — in  this  gray  matter  represents  a  certain  kind  of  intelli- 

'  and  '  L.  C.  Gray,  "Annals  of  Anatomical  and  Surgical  Society,"  October,  1880. 
'  For  the  discussion  as  to  the  merits  and  demerits  of  this  theory,  the  reader  is  refenwli 
to  the  late  text-book  of  Michael  Foster  on  physiology. 


Jl 


SPINAL  AUTOMATISM  AND  REFLEXES.  593 

gence,  and  that  these  cells  are  probably  in  communication 
with  one  another  by  means  of  white  fibers.  It  is  the  sum 
total  of  these  intelligences  that  imparts  to  the  cord  its  charac- 
teristics as  an  organ.  As  each  one  of  these  cellular  groups 
and  its  inherent  intelligence  is  more  or  less  independent  of  all 
others,  so  the  combined  intelligence  of  the  cord's  gray  matter 
is  independent  of  the  combined  intelligence  of  other  collec- 
tions of  gray  matter ;  and  it  is  a  recognized  fact  that  the 
spinal  cord  has  a  '  function '  of  its  own.  This  has  been  ex- 
emplified by  experiments  upon  headless  frogs  and  decapitated 
human  beings.  Cut  off  the  head  of  a  frog,  permit  it  to  re- 
cover from  the  sho6k  of  the  operation,  then  pinch  its  skin, 
and  it  will  hop  away ;  or,  throw  it  into  water,  and  it  will 
swim.  Place  a  drop  of  acetic  acid  upon  the  belly  of  such  a 
frog,  and  it  will  endeavor  to  brush  away  the  irritation  with 
one  foot.  Now  amputate  the  leg  of  this  foot  at  the  knee. 
The  animal  will  make  several  futile  attempts  to  reach  the 
irritated  spot  with  the  stump,  and  failing  will,  after  some 
hesitation,  make  use  of  the  uninjured  limb  for  this  purpose. 
It  is  easy  to  repeat  this  well-known  experiment  of  Pfluger's.* 
Robin"  witnessed  some  most  instructive  phenomena  in  a 
criminal  whose  head  had  been  removed  an  hour  previous  at 
the  level  of  the  fourth  cervical  vertebra.  The  skin  around 
the  nipple  was  scratched  with  the  point  of  a  scalpel.  Imme- 
diately there  ensued  a  series  of  rapid  movements  in  the  upper 
extremity,  which  had  been  extended  upon  the  table.  The 
hand  was  brought  across  the  chest  to  the  pit  of  the  stomach, 
simultaneously  with  a  semi-flexion  of  the  forearm  and  inward 
rotation  of  the  arm — a  movement  of  defense,  as  it  were.  All 
this  teaches  us  the  more  clearly  to  understand  that  it  is  the 
intelligence  of  the  cord's  gray  matter  that  is  called  into  play 
in  a  thousand  actions  that  must  take  place  without  the  aid  of 
that  conscious  intelligence  which  we  call  '  mind.'  The  intel- 
ligence of  the  spinal  cells  is  quite  sufficient  to  enable  men  to 
walk,  to  play  on  musical  instruments,  to  become  experts  in 

^  Pfliiger,  "  Die  sensorische  Function  des  Riickenmarks,"  1853. 
2  "  Jour,  de  TAnat.  et  de  la  Physiol.,"  Paris,  1869. 


594  THE  SPINAL   CORD,  I 

handiwork,  to  ride  on  horseback,  whether  awake  or  asleep,  to   \ 
become  acrobats,  and  to  unconsciously  acquire  such  a  hand- 
writing that  its  minute  peculiarities  shall  be  unerringly  recog-   i 
nized  by  the  trained  eye."  I 

Those  forms  of  reflex  action  which  are  independent  of  the   ' 
influence  of  the  will  or  intelligence  must  be  attributed  to  the   ''■ 
gray  matter  of  the  cord.     We  are  as  yet  somewhat  uncertain   \ 
in  regard  to  the  paths  which  serve  to  convey  sensory  impres-   ^ 
sions  (received  unquestionably  by  means  of  the  posterior   , 
nerve  roots)  to  the  ganglion  cells  of  the  anterior  horns.     The  \ 
histological  structure  of   this  part  of  what  is  termed  the   i 
''  nervous  circle"  of  a  reflex  act  is  not  definitely  determined.    ■ 
There  are  supposed  to  be  various  connections  established  be-   < 
tween  the  different  paths  of  sensory  and  motor  conduction  of  j 
the  cord  and  the  special  centers  that  are  also  known  to  exist  1 
within  its  substance.     An  excitation  of  a  sensory  nerve  may  \ 
therefore  pass,  in  some  instances,  to  many  of  the  motor  paths,    ■ 
or,  again,  only  to  one.     This  depends  often  upon  the  strength  ! 
of  the  excitation,  because  the  different  paths  are  supposed  to  ! 
afford  different  degrees  of  resistance  to  conduction.     Helm- 
holtz  has  shown  that  the  time  required  for  the  perfect  elabora- 
tion of  a  reflex  act  is  from  twelve  to  fourteen  times  greater 
than  for  simple  motor  conduction.    We  know,  clinically,  that 
the  degree  of  reflex  excitability  differs  with  individuals  in 
health,  and  that  it  is  also  greatly  modified  by  disease,  poisons, 
and  many  physiological    conditions.      An   increase  in  the 
strength  of  the  sensory  irritation,  or  any  condition  that  tends 
to  diminish  the  resistance  to  conduction  in  the  reflex  paths  of 
the  cord,  will  necessarily  increase  the  reflex  movements  pro- 
portionately.    Again,  a  sensory  excitation  may  create  a  re- 
sponse confined  to  one  spinal  segment  in-  one  individual,  and, 
by  a  more  extensive  conduction  in  the  case  of  another  indi- 
vidual, a  similar  excitation  may  elicit  a  response  from  many 
spinal  segments.     Some  reflex  acts  are  exceedingly  compli- 
cated, as,  for  example,  the  act  of  defecation.     As,  in  the  case 
of  Robin's  experiments  upon  the  beheaded  criminal,  and  those 
commonly  observed  in  the  beheaded  frog,  purely  reflex  move- 


SPINAL  AUTOMATISM  AND  REFLEXES,  695 

ments  may  appear,  under  certain  circumstances,  to  be  adapted 
to  certain  ends,  as  those  of  self-defense,  etc. 

Any  of  the  sensitive  parts  of  the  body  may  be  employed 
as  a  means  of  exciting  reflex  movements.  The  skin  is  the 
one  commonly  employed  in  the  clinical  examination  of  the 
condition  of  the  spinal  segments,  when  organic  diseases  of 
the  cord  are  suspected.  The  skin  of  the  sole,  of  the  inner 
aspect  of  the  thigh,  of  the  buttock,  of  the  belly,  of  the  region 
of  the  scapula,  and  of  the  face,  are  especially  liable  to  cause 
reflex  movements  when  subjected  to  slight  irritation  by 
scratching  it  with  a  pin  or  the  finger-nail.  Again,  the  sen- 
sory nerves  of  the  muscles  may  be  employed  as  a  means  of 
eliciting  reflex  spinal  movements.  The  muscle  to  be  tested 
should  first  be  put  in  a  state  of  moderate  tension,  and  a  smart 
stroke  given  over  its  tendon  with  the  edge  of  the  hand  or  a 
percussion-hammer.  When  the  irritability  of  the  cord  is 
rendered  very  excessive  by  disease,  a  series  of  rhythmical 
movements  known  as  a  ''  clonus"  may  be  excited  by  simply 
putting  muscles  upon  the  stretch  and  holding  them  in  that 
position  for  a  time. 

Among  the  reflex  movements  that  are  constantly  being 
excited  in  health,  and  which  are  important  aids  in  the  per- 
formance of  the  various  functions  of  the  body,  may  be  men- 
tioned the  movements  of  the  stomach  and  intestine,  the  acts 
of  erection  and  seminal  ejaculation  and  that  of  expulsion  of 
the  foetus,  the  sequence  of  muscular  contractions  required  in 
defecation  and  micturition,  and  the  important  reflex  processes 
which  occur  in  the  blood-vessels. 

The  so-called  "superflcial"  or  '*skin  reflexes"  and  the 
*'  deep  "or  *'  tendon  reflexes  "  are  especially  valuable  in  diag- 
nosis, and  deserve  a  detailed  description.  I  take  the  liberty 
of  quoting  from  the  third  edition  of  my  work  on  *'  Surgical 
Diagnosis"  the  following  extract : 

*'  The  ^superficial'  or  'skin  reflexes,'  which  have  been 
referred  to,  are  each  performed  by  different  segments  of  the 
cord.  Thus,  stimulation  of  the  skin  of  the  sole  of  the  foot  by 
a  scratch,  prick,  or  touch  with  the  nail,  for  example,  induces 


596  THE  SPINAL   CORD. 

the  contraction  of  the  foot-muscles  {plantar  reflex)  through 
the  lower  part  of  the  lumbar  enlargement  of  the  cord ;  the 
skin  of  the  buttock  calls  into  action  the  glutei  muscles  {glu- 
teal reflex)  through  a  segment  which  corresponds  to  the 
escape  of  the  fourth  or  fifth  lumbar  nerve  ;  the  skin  upon  the 
inner  aspect  of  the  thigh  causes  the  cremaster  muscle  to  draw 
the  corresponding  testicle  toward  the  external  abdominal  ring 
{cremaster  reflex)  by  influencing  the  cord  at  the  level  of  the 
first  or  second  lumbar  nerve  ;  the  skin  upon  the  side  of  the 
abdomen  creates  reflex  movements  of  the  abdominal  muscles 
{ahdominal  reflex)  by  affecting  a  segment  of  the  cord  situated 
between  the  levels  of  the  eighth  and  twelfth  dorsal  nerves ; 
the  skin  upon  the  side  of  the  chest  creates  a  reflex  response 
in  the  region  of  the  epigastrium  {epigastric  reflex\  which 
depends  upon  a  spinal  segment  extending  from  the  fourth  to 
the  seventh  dorsal  nerves  ;  finally,  the  skin  between  the 
shoulder-blades  causes  the  posterior  axillary  fold  or  the  teres- 
major  muscle  to  contract  {scapular  reflex)  by  influencing  the 
spinal  segment  between  the  levels  of  the  fifth  cervical  and 
third  dorsal  nerves. 

''By  means  of  these  reflexes,  we  are  enabled  to  test  the 
various  spinal  segments  from  the  neck  to  the  terminal  ex- 
tremity of  the  cord.  Should  any  be  found  to  be  absent,  it 
should  be  remembered :  (1)  that  the  reflex  excitability  of  the 
cord  varies  with  individuals  and  is  always  greater  in  youth 
than  in  old  age ;  (2)  that  the  plantar,  cremasteric,  abdomi- 
nal, and  epigastric  reflexes  are  variable  in  health,  but  are 
more  constant  than  the  scapular;  (3)  that  cerebral  lesions 
may  impair  them  on  the  side  of  the  hemiplegia,  for  rea- 
sons not  as  yet  well  understood  ;  and  (4)  that  systematic 
lesions  of  Burdach's  or  GoU's  columns  tend  to  diminish  or 
abolish  them. 

''The  'deep'  or  'tendon  reflexes'  are  also  of  great 
value  as  a  means  of  determining  the  condition  of  excitability 
of  different  segments  of  the  cord.  The  ones  now  commonly 
employed  are  called  the  ^ foot-clonus  \'  the  ^  knee-jerlc^  or 
^patella   rq/lex\'  the    ^peroneal   reflex'' ;  and  the   Hendo- 


i 


THE  VARIOUS  TENDON  REFLEXES.  597 

AcMlUs  reflex.^  The  method  of  obtaining  these  reflexes  in 
the  most  satisfactory  manner  will  be  described  separately.  It 
is  important,  however,  to  remember  one  fact  in  connection 
with  them  before  deciding  as  to  their  clinical  significance, 
viz.,  that  the  reflexes  should  he  tested  upon  both  sides  and 
compared  with  each  other ^  because  any  perceptible  differences 
between  the  two  sides  is  a  probable  indication  of  some  patho- 
logical lesion  of  the  cord. 

"The  Jcnee-jerk  has  for  years  been  recognized  and  em- 
ployed by  Charcot  in  diagnosis,  although  it  was  first  system- 
atically investigated  as  a  clinical  symptom  by  Westphal  and 
Erb.  Gowers  remarks  in  a  late  work,  *  It  is  not  a  little 
curious  that  this  knee-jerk,  w^hich  for  generations  has 
amused  school-boys,  should  have  become  an  important  clini- 
cal symptom.' 

"To  properly  test  this  refiex  movement  of  the  limb,  the 
muscles  of  the  quadriceps  extensor  tendon  must  be  put  upon 
the  stretch  to  a  moderate  degree,  and  the  leg  be  unrestricted 
in  its  ability  to  respond.  The  common  method  employed  is 
to  have  the  patient  cross  the  leg  over  the  knee  and  allow  it  to 
hang  passively  at  an  angle  which  is  nearly  ninety  degrees. 
Perhaps  a  stiU  better  way  is  that  employed  by  Gowers,  viz., 
to  allow  it  to  hang  over  the  forearm  of  the  physician  when 
his  hand  is  placed  upon  the  opposite  knee  of  the  patient,  be- 
cause in  this  way  the  jerk  is  often  elicited  in  stout  people 
when  it  otherwise  fails.  The  space  between  the  patella  and 
the  tibia  is  then  struck  with  a  percussion-hammer  or  the  side 
of  the  physician's  hand  upon  the  bare  skin  with  sufficient 
force  to  slightly  increase  the  state  of  muscular  tension  which 
has  resulted  from  flexion  of  the  leg.  This  will  cause  a  reflex 
contraction  of  the  quadriceps  extensor  muscle,  and  the  foot 
will  be  jerked  upward  without  the  volition  of  the  patient  as 
a  factor  in  the  movement.  In  about  two  per  cent  of  healthy 
subjects,  the  knee-jerk  may  be  found  to  be  totally  absent,  in 
spite  of  all  possible  care  in  employing  the  test.  This  fact  is 
important,  since  the  absence  of  the  knee-jerk  is  too  often 
construed  as  a  positive  sign  of  spinal  disease. 


598  THE  SPINAL   CORD. 

"  The  anJcle-jerk.  If  the  muscles  of  the  tendo  Achillis  be 
put  upon  the  stretch  by  flexion  of  the  foot,  a  blow  upon  that 
tendon  will  cause  a  similar  extension  of  the  foot. 

''The foot- clonus.  When  the  excitability  of  the  cordis 
excessive,  if  the  foot  be  firmly  flexed  and  held  so  by  the 
pressure  of  the  hand  against  the  sole,  a  series  of  rhythmical 
reflex  movements  of  extension  follows,  which  vary  between 
six  and  ten  per  second.  They  can  be  traced  upon  a  revolv- 
ing drum  by  attaching  a  pencil  to  the  foot,  as  easily  as  a 
sphygmographic  tracing  is  made.  This  clonus  is  more  ap- 
parent when  the  knee  is  firmly  extended  than  when  flexed. 

''  The  peroneal  reflex.  The  tendons  of  the  peroneal  mus- 
cles pass  to  the  bones  of  the  foot  at  the  outer  side  of  the 
ankle.  A  blow  made  upon  them  when  the  foot  is  bent  in- 
ward, to  produce  a  moderate  degree  of  tension  of  these  mus- 
cles, will  elicit  a  reflex  movement,  as  in  the  case  of  the  patella 
tendon. 

''The  'front-tap  contraction.'*  Gowers  has  described  a 
reflex  test  for  increased  spinal  irritability  that  he  considers 
particularly  delicate.  It  consists  in  flexing  the  foot  with  the 
hand  upon  the  sole,  the  knee  being  extended,  and  applying 
the  blow  to  the  muscles  on  the  anterior  aspect  of  the  leg.  It 
is  followed  by  a  reflex  contraction  of  the  muscles  of  the 
tendo  Achillis  which  are  not  directly  affected  by  the  blow. 

"  Although  the  deep  reflexes  are  commonly  tested  only  in 
the  lower  extremities,  the  same  phenomena  may  be  elicited 
in  the  triceps  or  biceps  muscle  of  the  arm  as  in  those  of  the 
thigh  and  calf,  if  subjected  to  the  necessary  position  to 
insure  tension  of  the  muscles  before  the  tap  is  given  over  the 
tendon." 

Before  we  leave  the  subject  of  the  spinal  cord  and  its 
architecture,  it  may  be  well  to  consider  some  of  the  bear- 
ings which  anatomy  and  physiology  have  upon  the  clinical 
recognition  of  disease  confined  to  this  wonderful  piece  of 
mechanism. 

The  hints  which  are  thrown  out  in  the  remaining  pages 
of  this  section  must  of  necessity  be  crude  and  incomplete 


J 


KINESODIC  AND  JESTHESOBIG  SYSTEMS.  599 


CLII!^ICAL   POIIfTS   PERTAINING   TO   THE   SPINAL   CORD. 

From  the  physiological  experiments  as  to  the  functions  of 
the  different  columns  of  the  cord,  it  now  seems  possible  to 
divide  the  spinal  cord  into  two  great  subdivisions,  which  will 
be  of  interest  from  a  purely  clinical  standpoint,  as  well  as 
from  a  physiological  aspect.  The  first  of  these  includes 
both  pyramidal  columns  and  the  anterior  horns  of  the  gray 
matter,  and  is  the  probable  path  of  all  motor  impulses  which 
traverse  the  cord,  as  well  as  the  seat  of  *'  trophic  influences  " 
upon  tissues.  The  latter  includes  the  posterior  and  cere- 
bellar columns  and  the  posterior  horns,  and  is  the  probable 
path  of  sensory  impulses,  while  it  also  is  associated  with 
the  function  of  coordination  of  movement.  Now,  both  of 
these  subdivisions  include  several  parts  of  the  spinal  cord, 
which  have  been  separately  named  in  previous  pages  ;  hence, 
the  term  ''system"  is  applied  to  both,  the  former  be- 
ing named  the  ''' Mnesodic  system^^'^  and  the  latter  the 
'' cesthesodlc  system^  These  names  will  be  constantly 
used,  therefore,  when  the  portions  of  the  cord  which  con- 
vey either  motor  or  sensory  impulses  are  spoken  of  as  a 
whole  ;  while  the  other  names  applied  to  special  portions 
of  the  cord  will  chiefly  be  used  in  defining  the  situations 
of  special  lesions  whose  symptomatology  may  be  under  dis- 
cussion. 

If  we  are  to  attempt  to  grasp  the  symptoms  by  which  the 
various  lesions  of  the  spinal  cord  may  be  recognized  during 
life,  and  to  understand  why  certain  effects  must  be  produced 
(when  the  situation  of  the  lesion  is  known  to  us),  we  must 
make  some  classification  of  the  diseases  which  affect  the  spinal 
cord  on  such  an  anatomical  and  physiological  basis  as  shall 
naturally  tend  toward  the  constant  application  of  these 
branches  of  medical  science  to  the  symptoms  presented  by 
the  patient.  It  has  been  customary  with  most  of  the  late 
authors  upon  the  special  subject  of  nervous  affections  to  con- 
sider the  diseases  of  the  motor  regions  and  of  the  sensory 
regions  of  the  cord  separately;  using  the  term  "systematic 


600  THE  SPmAL   CORD. 

lesions  "  to  express  tlie  fact  that  all  of  those  diseases,  which  " 
are  not  purely  local,  affect  either  the  kinesodic  or  sesthesodic 
systems.  When  we  speak  of  systematic  lesions,  therefore, 
we  mean  those  types  of  disease  which  tend  to  diffuse  them- 
selves, for  a  greater  or  less  extent,  upward  and  downward, 
without  extension  to  the  adjacent  columns  ;  thus  the  columns 
of  Goll  and  of  Burdach  may  be  involved  in  the  sesthesodic 
system,  the  lateral  columns  and  the  columns  of  Tiirck  may 
be  involved  in  the  kinesodic  system,  while  the  anterior  or 
posterior  horns  or  central  part  of  the  gray  matter  may  be 
the  seat  of  disease,  irrespective  of  the  other  parts  of  the 
cord. 

In  contradistinction  to  the  systematic  lesions,  certain 
types  of  disease  tend  to  spread  laterally,  and  thus  to  involve 
different  columns  of  the  cord  in  succession.  These  are  grouped 
under  the  general  head  of  "focal  lesions  "  or  ''  non- systematic 
lesions.^''  In  this  form  of  degeneration,  or  of  new  tissue 
development,  the  extension  is  usually  limited  in  a  vertical 
direction,  but  it  may  extend,  laterally,  not  only  to  diverse 
columns,  but  may  even  involve  both  the  kinesodic  and 
aesthesodic  systems  in  its  progress. 

It  will  exceed  the  proper  scope  of  the  course  of  lectures 
which  I  have  prepared  for  this  winter,  to  enter  into  a  full  de- 
scription of  the  symptoms  of  all  of  the  diseases  of  the  spinal 
cord ;  but  it  is  important  that  you  start  with  a  general  classi- 
fication of  the  diseases  which  may  affect  this  region,  in  order 
that  you  may  properly  understand  the  meaning  of  terms 
which  you  will  find  growing  into  use  with  astonishing  rapid- 
ity. It  is  also  to  be  remembered  that  the  classification  which 
I  have  given  you  is  based  on  anatomy  and  pathology,  and 
may  differ  markedly  from  those  of  some  authors  with  which 
you  may  be  familiar ;  a  little  study  will,  however,  remove  all 
confusion,  and  perhaps  add  to  your  more  perfect  comprehen- 
sion of  the  subject. 


SYSTEMATIC  LESION'S  OF  MSTEESODIG  SYSTEM.       601 


A   CLASSIFICATION   OF  THE   DISEASES   OF   THE   SUBSTAi^^CE   OF  THE 
SPINAL   CORD.       (after   SEGUIN.) 


"  SYSTEMATIC  " 
LESIONS. 


"  NON-SYSTEM- 
ATIC"  or  "FO- 
CAL" LESIONS. 


Lesions  of  the  yEs- 
thesodic  System. 


Lesions  of  the  Ki- 
nesodic  System. 


Sclerosis  of  the  columns  of  Goll, 
Sclerosis  of  the  columns  of  Burdach  (locomo- 
tor ataxia), 
^^  Ascending  degeneration. 
Sclerosis  of  the  anterior  columns, 
Sclerosis  of  the  lateral  columns  (tetanoid  para- 
plegia), 
Sclerosis  of  anterior  horn  and  lateral  column. 
Myelitis  of  the  anterior  horns  (atrophic  spinal 

paralysis). 
Degeneration  of  the  ganglion  cells  of  the  ante- 
rior horns  (progressive  muscular  atrophy), 
(^  Central  myelitis. 
Traumatism  of  the  cord. 

Compression  of  the  cord,  by  j  r^^^l 

■<    Transverse  sclerosis  of  the  cord. 

Transverse  softening  of  the  cord, 

Haemorrhage  into  the  cord, 
(^  Tumors  of  the  cord. 


''SYSTEMATIC  LESIONS"   OF  THE   "^STHESODIO   SYSTEM." 

In  the  table '  which  I  have  written  out  for  your  inspection, 
you  wiU  perceive  that  the  systematic  lesions  may  affect  either 
the  sesthesodic  or  kinesodic  systems  of  the  spinal  cord,  while 
the  focal  lesions  are  not  thus  separated,  since  they  tend  to 
extend  in  a  transverse  direction,  and  thus  may  be  found  in 
both.  As  the  sesthesodic  system  presents  well-recognized  and 
understood  morbid  conditions,  we  will  first  study  the  general 
effects  of  systematic  disease  which  is  confined  either  to  the 
columns  of  Goll  or  of  Burdach. 

We  might  begin,  possibly  with  advantage,  by  stating  that 
the  general  results  of  any  lesion  situated  back  of  the  posterior 
gray  horn  of  the  cord  must  manifest  itself,  if  our  previous  de- 
ductions are  correct,  by  symptoms  referable  only  to  sensation 
and  coordination.  This  we  find  to  be  approximately  correct. 
We  have  in  this  type  of  cases  ancesthesia,  hyper cestJiesia,  or 
numbness,  and  also  pain  (usually  possessing  some  special 
characteristics  which  are  of  clinical  value) ;  while  coordi- 
nation is  unquestionably  affected  as  well,  since  a  peculiar 


See  the  foregoing  table. 


602  THE  SPINAL   CORD. 

disorder  of  voluntary  movements,  which  constitutes  true 
''ataxia,"  is  usually  developed.  Our  previous  statements  as 
to  the  path  of  the  motor  impulses  of  the  cord  seem  to  be  con- 
firmed by  the  absence  of  either  spasm  or  true  paralysis  of 
the  muscles  below  the  lesion. 

The  question  now  arises,  "  Can  we  tell  whether  the  disease 
is  confined  to  the  columns  of  GoU  or  of  Burdach  ? "  We  can 
undoubtedly  locate  the  lesion  in  the  opposite  side  of  the  cord 
from  that  of  the  body  upon  which  certain  symptoms  are  well 
marked ;  but  can  we  tell  positively  whether  the  lesion  is  pro- 
gressing in  the  inner  or  outer  column  of  the  posterior  half  of 
the  cord  when  both  sides  are  simultaneously  involved  ? 

SCLEROSIS   OF  THE   COLUMNS   OF   GOLL. 

As  regards  the  columns  of  Goll,  I  feel  myself  forced  to  say 
that  I  do  not  believe  that  localized  disease  can  be  positively 
diagnosed  when  confined  to  these  columns ;  although,  from 
certain  pathological  deductions,  we  can  often  infer  that  it 
exists^  since  it  has  been  found  to  occur  as  a  secondary  result 
of  those  other  lesions  which  are  capable  of  producing  an  as- 
cending or  descending  degenerative  process  in  the  spinal  cord. 
As  the  columns  of  Goll  are  large  and  distinct  in  the  cervical 
region  of  the  cord,  but  become  narrower  and  narrower  as  the 
lower  portion  of  the  cord  is  reached,  the  lesion  of  this  column 
becomes  more  evident  to  ocular  demonstration,  when  present, 
as  you  ascend  the  cord.  The  entire  length  of  either  column 
may  be  affected,  or  only  portions  of  it.  In  the  ascending 
form  of  secondary  degeneration  of  these  columns,  the  lesion 
is  always  observed  above  the  seat  of  the  exciting  cause.  This 
lesion  has  never  been  traced,  so  far  as  my  researches  go,  above 
the  "calamus  scriptorius." 

SCLEROSIS   OF  THE   COLUMNS   OF   BURDACH    (LOCOMOTOR   ATAXIA). 

The  columns  of  Burdach  are  the  seat  of  sclerosis  more 
commonly  than  those  of  Goll,  since  this  type  of  change  pro- 
gresses, as  a  rule,  from  the  posterior  root  zones  inward,  and 
thus  only  affects  the  columns  of  Goll  after  those  of  Burdach 


PROGBESSIVE  LOCOMOTOR  ATAXIA,  603 

have  become  seriously  impaired.  In  all  those  cases  where  the 
symptoms  of  pain  and  alteration  in  the  sensibility  of  parts 
precede  those  of  ataxia,  we  find  the  columns  of  Burdach  first 
affected  with  a  systematic  lesion,  and,  afterward,  those  of 
Goll.  The  investigations  of  Pierret  and  Charcot  seem  to  de- 
monstrate that  the  condition  of  sclerosis  of  the  columns  of  Bur- 
dach usually  begins  in  the  lumbar  enlargement,  and  tends  to 
creep  gradually  upward  toward  the  medulla  oblongata,  so  that 
the  entire  length  of  the  cord  may  become  hardened  and  atro- 
phied ;  while  the  same  condition  of  the  columns  of  Goll  is 
usually  found  to  coexist,  but  may  be  looked  upon  as  a  sec- 
ondary result  of  the  former. 

Now,  we  have  mentioned  certain  peculiar  symptoms  which 
point,  when  present,  to  some  disease  of  the  posterior  columns 
of  the  spinal  cord,  among  which  come  jpain^  hyper cesthesia^ 
numbness^  ancestJiesia^  and  symptoms  of  incodrdination 
(ataxia)  when  the  disease  is  far  advanced.  We  discover  no 
motor  symptoms,  as  the  muscular  power  appears  to  be  normal 
in  all  respects,  except  in  coordinate  movement ;  and  ''  trophic 
changes"  '  in  tissues  are  produced  less  frequently  than  if  the 
anterior  portion  of  the  cord  were  involved.  It  will  help  us  to 
recognize  this  disease,  if  we  will  study  a  little  more  in  detail 
each  of  these  various  manifestations  of  posterior  spinal  lesions. 

In  the  first  place,  the  pains  of  this  type  of  sclerosis  are 
peculiar.  They  do  not  follow  the  course  of  special  nerve 
trunks,  as  do  neuralgic  pains,  but  are  more  localized.  They 
are  vagrant  in  character,  since  they  affect  innumerable  spots 
in  the  region  which  is  presided  over  by  the  nerves  connected 
with  the  diseased  portion  of  the  cord  ;  and  so  marked  is  this 
peculiarity  that  a  patient  who  has  long  suffered  with  these 
pains  can  not  well  select  any  spot  which  has  entirely  escaped 
them.  Again,  the  pains  vary  in  their  intensity,  since  they  are 
more  or  less  paroxysmal,  and  often  show  exacerbations  due  to 
atmospheric  changes.  These  exacerbations  may  occur  every 
few  minutes  for  some  hours,  and  may  then  disappear  for 

^  Trophic  changes  in  connection  with  posterior  sclerosis  point  often  to  a  complicating 
peripheral  neuritis. 


eOi  THE  SPINAL   CORD. 

days  or  weeks  ;  the  area  covered  by  them  may  vary  from  that 
of  a  small  point  to  that  of  your  hand  ;  and  they  may  be  re- 
ferred to  the  sldn  alone,  the  muscles,  the  joints,  the  bones, 
or,  in  rare  cases,  to  the  viscera.  These  pains  are  usually  of  a 
sudden  character,  and  extremely  severe.  They  assume  the 
character  of  stabbing,  tearing,  or  shooting  sensations,  which 
often  cause  the  patient  to  shriek  in  agony ;  while  the  skin 
over  the  circumscribed  spot  is  rendered  hypersesthesic  to 
slight  pressure,  although  firm  pressure  often  affords  relief. 
The  terms  *' fulgurating"  and  "  terebrating  "  are  often  applied 
to  these  pains,  from  their  sudden  onset  and  their  similarity  to 
the  effects  of  a  passage  of  a  strong  electric  current.  In  fact, 
the  distinctive  characteristics  of  the  pain  of  sclerosis  of  the 
posterior  columns  of  the  spinal  cord  are  so  well  defined  that  I 
seldom  hesitate  to  predict  the  development  of  later  ataxic 
symptoms  from  this  guide  alone.  It  is  usually  confined  to  the 
lower  extremities  (toes,  foot,  shin,  calf,  and  thigh),  but  it 
sometimes  affects  the  trunk  and  the  upper  extremity,  and,  in 
very  rare  cases,  the  head.  It  is  to  be  differentiated  from  the 
pain  of  rheumatism  or  of  a  simple  neuralgia,  and,  as  it  is  the 
initial  symptom  of  a  serious  and  incurable  disease,  it  should 
be  recognized  early. 

Touching  upon  this  point.  Professor  E.  C.  Seguin,  in  a  late 
lecture,  puts  the  diagnosis  of  this  affection,  with  his  accus- 
tomed clearness,  as  follows : 

**  The  only  two  conditions  in  which  pains  somewhat  resem- 
bling fulgurating  pains  occur,  in  my  experience,  are  paralytic 
dementia  and  gout.  In  the  former  disease,  slight  fulgurating 
pains — 'smaller'  pains,  if  I  may  be  allowed  the  expression — 
are  described  by  the  patients ;  but,  in  many  of  these  cases, 
autopsy  shows  that,  besides  the  cerebral  lesions  proper  to  the 
disease,  the  posterior  columns  of  the  cord  exhibit  pathological 
alterations ;  so  that  these  cases  are,  after  all,  quasi-i^hetiG, 
The  sharp  pains  of  gout  are  short,  stabbing  pains  in  the  skin 
of  various  parts  of  the  body,  compared  by  the  patients  to 
the  prick  of  a  needle,  cold  or  hot.  There  is  no  tendency  to 
repetition  of  the  pain  in  one  spot  for  hours  or  days  ;  the  sen- 


TEE  PAIRS  OF  LOCOMOTOR  ATAXIA.  605 

sations  appear  in  various  parts  of  the  body,  and  are  bear- 
able. 

^'  The  differential  diagnosis  of  fulgurating  pains  from  the 
pains  of  neuralgia,  strictly  speaking,  is  very  easy.  In  neural- 
gia the  pain  is  in  the  course  and  distribution  of  one  or  two 
(single)  nerve  trunks  and  their  branches ;  it  may  be  parox- 
ysmal, but  does  not  assume  the  excessive  irregularity  of  ta- 
betic pains,  viz.,  agony  for  a  few  hours,  and  freedom  from 
pains  for  hours,  days,  or  weeks.  The  hypersesthesia,  in  ful- 
gurating pains,  is  at  the  seat  of  pain.  In  neuralgia,  we  find 
regular  '  tender  points '  along  the  nerve  trunk,  or  where  its 
branches  become  superficial.  The  lightest  touch  causes  pain 
in  the  painful  districts  in  tabes,  while  the  tenderness  of 
nerves  in  neuralgia  is  usually  demonstrable  only  by  firm, 
localized  pressure.  Further,  true  neuralgia  is  seldom  bilat- 
eral, while  it  is  the  rule  for  fulgurating  pains  to  appear  on 
both  sides  of  the  median  line — in  both  lower  extremities,  for 
example.  A  last  important  distinction  is  that  neuralgia  is 
relievable  or  curable,  whereas  fulgurating  pains  are  practi- 
cally incurable,  and  fully  relieved  only  by  morphia  injections. 

'^The  confusion  so  often  made  between  'rheumatism'  and 
the  first  stage  of  sclerosis  is  even  less  pardonable.  Of  course, 
no  practitioner  would  mistake  fulgurating  pains  for  articular 
rheumatism;  the  error  is  with  respect  to  'rheumatism,'  so 
called,  affecting  muscular  masses  and  aponeuroses.  In  these 
affections  the  pains  are  usually  dull,  nearly  constant,  and  dis- 
tinctly aggravated  by  movements.  Pressure  must  be  firmly 
made  upon  the  parts  to  produce  pain,  whereas  in  fulgurating 
pains  the  condition  is  one  of  cutaneous  hyperalgesia  under  a 
slight  touch.  Again,  this  '  rheumatic '  condition  is  distinctly 
amenable  to  treatment  (counter-irritants,  etc.),  whereas  the 
pains  of  posterior  spinal  sclerosis  are,  in  one  sense,  incurable." 

Now,  this  symptom  may  exist  for  years  without  the  de- 
velopment of  marked  anaesthesia  or  of  ataxia,  and  often  both 
the  patient  and  the  physician  are  inclined  to  speak  of  these 
pains  as  dependent  upon  some  rheumatic  diathesis,  rather 
than  as  a  precursor  of  an  incurable  affection.     The  peculiar 

41 


606 

hypersesthesia  which  exists  in  the  patches  of  skin  affected 
with  the  pain,  both  during  the  paroxysm  and  sometimes  for 
hours  afterward,  affords  a  point  of  great  diagnostic  value. 

As  regards  the  second  diagnostic  symjytom—ancBsthesia — 
it  is  claimed  that  an  alteration  in  the  sensibility  of  the  af- 
fected parts  can  be  detected  in  the  earliest  stages  of  the  dis- 
ease, as  well  as  later  on  ;  but,  in  the  former  case,  the  loss  of 
sensation  is  localized  in  distinct  spots  or  patches  of  integu- 
ment (usually  upon  the  lower  extremities,  but,  possibly,  upon 
the  trunk  and  arms,  if  the  disease  be  extensive),  while,  in  the 
later  stages,  the  soles  of  the  feet  become  deprived  of  sensi- 
bility, and  the  anaesthetic  condition  tends  to  extend  upward 
along  the  legs  and  thighs  until  the  whole  of  the  affected  re- 
gions may  be  dead  to  all  sensations.  Now,  it  is  this  very  con- 
dition of  the  integument  that  probably  causes  the  symptom 
which  is  regarded  by  many  physicians  as  pathognomonic  of 
locomotor  ataxia — staggering  or  falling,  when  the  eyes  are 
closed  and  the  patient  attempts  to  stand  erect — and  no  test  is 
more  worthless  of  this  special  affection.  I  have  seen  a  patient 
made  to  fall,  when  his  eyes  were  closed,  by  simply  freezing 
the  soles  of  the  feet  so  as  to  render  them  incapable  of  sensa- 
tion, while  it  is  well  recognized  that  the  same  symptom  is  met 
with  in  the  anaesthesia  which  follows  or  accompanies  hysteria, 
myelitis  of  the  posterior  horns,  etc.  That  patients  afflicted 
with  locomotor  ataxia  do  stagger  and  often  fall,  when  obliged 
to  stand  erect  with  closed  eyes,  no  one  can  deny,  but  that  it 
has  no  special  diagnostic  value  can  now  be  as  positively  stated. 

In  the  final  stages  of  sclerosis  of  the  posterior  columns, 
symptoms  of  ataxia  develop.  The  walk  of  the  patient  now 
becomes  of  a  peculiar  character.  The  legs  are  jerked  about 
in  an  aimless  manner,  and  the  feet  are  brought  down  in  a 
stamping  way  which  is  totally  different  from  the  gait  of  pa- 
i-alysis.'    The  separate  muscles,  when  tested,  show  an  unim- 

'  This  symptom  may  develop  at  a  variable  period  from  the  commencement  of  the 
neuralgic  pains  (the  duration  of  the  pains  varying  from  three  months  to  ten  or  more 
years).  The  heel  strikes  the  ground  forcibly  in  walking.  If  the  upper  extremities  are 
involved,  the  fingers  and  arms  perform  unnecessary  movements  to  i*each  a  given  point, 
and  oscillate  when  a  given  action  is  attempted. 


VARIETIES  OF  ATAXIC  MANIFESTATION'S.  607 

paired  power,  but  the  large  groups  of  muscles  can  not  be 
employed  in  rhythmical  succession.  The  patient  begins  to 
notice,  in  the  early  symptoms  of  this  condition,  a  sense  of 
distrust  in  himself  in  crossing  a  street  or  in  performing  any 
act  which  calls  for  sudden  and  positive  muscular  coordina- 
tion. Later  on,  'walking  becomes  almost  impossible  if  the 
ataxic  symptoms  develop  rapidly,  and  the  patient  is  liable  to 
fall,  in  his  efforts  to  avoid  any  special  danger,  as  in  traveling 
the  streets. 

One  of  the  earliest  evidences  of  incoordination  of  movement 
usually  perceived  by  tabetic  patients  is  a  difficulty  in  direct- 
ing their  feet  toward  any  object  of  small  size,  such  as  a  car- 
riage-step, stirrup,  etc.  A  difficulty  is  also  experienced  by 
many  in  ascending  long  flights  of  stairs,  as  the  equilibrium  is 
preserved  with  some  difficulty,  on  account  of  an  uncertainty 
in  placing  the  feet  upon  the  stairs.  Later  on  in  the  disease, 
the  feet  are  swung  in  a  circle,  in  contrast  to  the  straight  pro- 
gression of  the  normal  step,  since  the  equilibrium  is  thus 
more  easily  preserved.  This  has  been  compared  to  the  swing- 
ing motion  of  the  tight-rope  performer.  The  sole  of  the  foot 
is  generally  brought  down  after  the  heel  strikes  the  ground, 
thus  often  giving  a  flapping  sound  to  the  step.  The  jerking 
gait  of  well-marked  ataxia  could  never  be  mistaken  for  that 
of  paralysis. 

When  the  upper  extremities  are  affected,  the  motions  of 
the  hand  show  even  more  decided  evidences  of  incoordination. 
Such  patients,  when  asked  to  place  the  tip  of  their  finger 
upon  any  designated  spot  on  the  face  (provided  the  eyes  are 
first  closed,  in  order  to  prevent  the  use  of  vision  as  an  aid  to 
movement),  utterly  fail  to  perform  the  act,  often  touching  a 
spot  one  or  two  inches  from  that  upon  which  they  intended 
to  place  their  finger. '  With  the  eyes  open,  a  glass  of  water  is 
carried  to  the  mouth  with  a  trembling  of  the  hand  and  partial 
spilling  of  its  contents  ;  and  the  finger  is  placed  upon  any 
point  designated  upon  the  face  by  being  suddenly  darted 
forward,  rather  than  by  a  deliberate  movement.  The  hand- 
writing is  markedly  altered,    especially  in  respect  to    the 


608  TEE  SPINAL   CORD. 

rounded  letters,  such  as  d,  b,  o,  c,  z ;  and  this  is  even  more 
marked  when  writing  is  attempted  with  the  eyes  closed,  as  it 
is  then  almost  unintelligible. 

The  complex  movements  of  the  fingers,  required  for  the 
act  of  buttoning  or  unbuttoning  the  clothing,  and  in  picking 
up  a  pin  from  the  floor,  are  performed  with  so  much  difiiculty 
that  they  afford  two  admirable  tests  for  this  disease,  provided 
the  upper  extremity  be  involved. 

Tabetic  patients  usually  walk  with  their  eyes  fixed  upon 
the  feet,  as  vision  aids  them  materially  in  guiding  their 
movements  of  progression ;  hence,  we  invariably  find  that 
closing  the  eyes  causes  a  marked  alteration  in  the  ataxic 
manifestations,  oftentimes  causing  them  to  fall  when  required 
to  stand  motionless. 

It  must  be  remembered,  however,  as  was  brought  out  in 
the  lectures  upon  the  brain,  that  certain  forms  of  intra-cra- 
nial  diseases  tend  to  produce  the  same  symptoms,  so  that 
ataxic  movements  are  only  confirmatory  of  a  spinal  disease 
which  has  previously  manifested  itself  by  well-marked  sen- 
sory symptoms. 

There  are  two  other  symptoms  referable  to  the  sensory 
nerves  which  are  of  value  in  deciding  as  to  the  probable  ex- 
istejice  of  posterior  spinal  sclerosis,  viz.,  a  retardation  of  sen- 
sation and  diminished  reflex  movement. 

If  we  prick  the  skin  of  a  patient  suffering  from  this  type 
of  disease,  and  count  the  time  which  intervenes  between  the 
time  of  the  puncture  and  the  time  when  the  patient  perceives 
it  (provided  the  eyes  be  closed,  so  as  to  prevent  any  visual 
recognition  of  the  pricking  of  the  part),  we  will  often  find 
that  an  interval,  varying  from  ten  to  one  hundred  or  more 
seconds,  may  be  detected.  This  has  been  explained,  by  sup- 
posing that  the  sclerosis  has  created  such  pressure  upon  the 
sensory  nerve  filaments  as  to  partially  or  nearly  completely 
destroy  the  axis  cylinders.  This  symptom  is  invariably  fol- 
lowed sooner  or  later  by  complete  anaesthesia,  and  by  a 
sense  of  numbness  which  extends   upward  from  the  feet, 


REFLEX   TESTS  FOR  LOCOMOTOR  ATAXIA.  609 

since  it  is  usually  perceived  in  the  lower  extremity  rather 
than  in  the  upper. 

In  addition  to  the  sensory  manifestations  already  dis- 
cussed, this  disease  tends  to  extend  upward  along  the  cord 
until  the  optic  apparatus  becomes,  in  some  way,  markedly 
affected.  The  perception  of  color  is  often  rendered  obscure, 
or  entirely  lost  for  the  red  and  green  tints  ;  while  the  patient 
may  possess  a  normally  acute  perception  of  the  yellow  or 
blue  tints,  or  even  have  an  unnatural  acuteness  in  detecting 
delicate  shades  of  these  colors. 

In  some  instances,  ptosis,  diplopia,  and  a  marked  altera- 
tion in  the  reflex  movement  of  the  iris  to  varying  degrees  of 
light,  are  developed  ;  and  these  may  prove  of  great  advantage 
to  you  in  tending  to  confirm  the  possible  existence  of  this 
type  of  spinal  sclerosis. 

During  the  first  stage  of  the  disease,  when  the  fulgurating 
pains  are  present,  all  the  reflex  movements  which  seem  to  be 
controlled  either  entirely  or  in  part  by  the  spinal  cord  are  di- 
minished. As  examples  of  this  fact,  we  frequently  see  that 
the  pupils  are  either  smaller  than  normal,  or  irregular  as  re- 
gards their  size,  or  that  they  do  not  properly  respond  to  fine 
variations  in  the  intensity  of  light,  ^  and  that  the  muscles  do 
not  respond  to  sensory  stimulation  of  the  skin.  If  the  knee 
be  semi-flexed  during  the  stage  of  fulgurating  pains,  or  even 
when  the  ataxic  symptoms  have  been  developed,  and  the  liga- 
mentum  patellae  be  struck  sharply  with  the  finger-end,  you 
will  notice  that  the  muscles  of  the  quadriceps  extensor  of  the 
thigh  fail  to  produce  any  responsive  movement  of  the  limb, 
since  the  reflex  action  of  the  spinal  cord  is  impaired.  This 
test  is  one  which  is  now  regarded  by  specialists  in  nervous 
diseases  as  one  of  great  value,  in  deciding  as  to  the  presence 
of  posterior  spinal  sclerosis,  and  it  is  known  as  the  ''patella 
reflex"  test." 

^  See  a  previous  page  of  this  volume. 

2  In  reference  to  the  diminution  of  the  different  reflexes,  much  has  ah-eady  been  men- 
tioned in  preceding  pages.  I  quote,  however,  a  summary  of  Professor  Seguin  upon  this 
point,  as  a  general  resume. 

"  We  test  the  so-called  patellar  reflex,  or  knee  reflex,  or  patellar  tendon  reflex,  in  the 


THE  SPINAL   CORD. 

Now,  it  must  be  evident  to  you  all,  that  the  symptoms 
which  have  been  hastily  enumerated  as  indicating  a  lesion  in 

followini;  ways :  the  patient,  being  seated,  is  told  to  cross  one  leg  over  the  other  in  a 
natural  manner,  and  to  let  the  muscles  relax ;  or,  seated,  we  place  our  left  hand  under  the 
popliteal  space,  tell  the  patient  not  to  help  us,  to  let  the  leg  hang  loose,  or,  in  popular 
parlance,  '  dead,'  and  lift  the  whole  limb  so  that  the  foot  swings  a  couple  of  inches 
above  the  floor  ;  then  we  tap  the  skin  over  the  whole  of  the  region  from  the  insertion  of 
the  quadriceps  femoris  to  the  tuberosity  of  the  tibia,  with  one  or  two  finger  tips  applied 
as  in  percussion.  The  place  whence  a  reflex  quadriceps  contraction  is  most  apt  to  occur 
is  about  midway  between  the  lower  end  of  the  patella  and  the  tibial  protuberance.  The 
taps  should  be  gentle  at  first,  and,  if  these  fail,  harder  ones  are  to  be  tried.  A  third 
mode  of  procedure,  which  is  very  good  indeed,  is  to  seat  the  patient  on  a  table  so  that  his 
legs  dangle  some  two  or  three  inches  beyond  its  edge ;  then  we  tap  the  patellar  region  as 
abbve  described,  without  supporting  the  thigh  with  our  left  hand.  The  test  may  be  well 
done  through  the  patient's  clothing,  yet  it  is  desirable,  especially  in  doubtful  cases,  to  tap 
the  bare  skin.  Another  important  precaution  is  to  secure  the  absolute  relaxation  of  the 
patient's  muscles,  and  to  divert  his  attention  from  what  you  are  doing.  Even  with  all 
precautions,  it  is  sometimes  next  to  impossible  to  secure  this  indispensable  muscular  re- 
laxation. In  the  healthy  subject  this  test  develops  a  contraction  of  the  quadriceps  ex- 
tensor femoris,  and  causes  an  extension  of  the  leg  or  a  sudden  jerk.  In  a  very  early 
stage  of  posterior  spinal  sclerosis  no  contraction  takes  place. 

"  I  would  also  call  attention  to  the  occasional  occurrence  of  reflex  movements  of  the 
thigh,  produced  by  contraction  of  the  iliac  group  of  muscles  during  the  knee  test.  I  have 
an  example  of  this  distant  reflex  action  in  a  t>-pical  case  of  sclerosis  of  the  posterior  col- 
umns, in  which  the  quadriceps  does  not  contract  at  all. 

"While  claiming  very  great  diagnostic  value  for  this  negative  symptom,  I  would  not  be 
understood  as  attaching  pathognomonic  significance  to  it,  as  we  all  know  that  there  are  a 
few  seemingly  healthy  individuals  in  whom  the  patellar  tendon  reflex  is  lacking,  and  also 
that  there  are  other  diseases  which  diminish  or  abolish  it.  Indeed,  I  may  say  that  I  rec- 
ognize no  pathognomonic  symptom,  and,  even  in  attempts  to  push  diagnosis  to  an  extreme 
delicacy,  would  urge  that  reliance  be  placed  on  the  grouping  of  symptoms,  rather  than  on 
any  one  of  the  signs,  however  constant  and  important  it  may  appear. 

"  Physiologically  analogous  to  this  condition  of  loss  of  tendinous  reflexes  is  the  flabby 
state  of  the  muscles  in  the  affected  parts.  This  is  not  due  to  any  positive  atrophy,  as 
electrical  tests  show  us  marked  departure  from  the  normal  reactions,  but  to  impairment 
of  what  physiologists  call  muscular  tonus — a  state  of  partial  contraction  or  tension  of 
muscles,  which  is  kept  up  by  the  inevitable  and  continued  excitation  of  the  cutaneous  nerves 
by  air,  clothing,  surrounding  objects,  etc.,  acting  in  a  reflex  way  through  the  spinal  cord. 
It  has  been  recently  claimed  that  this  loss  of  muscular  tonus  was  the  most  important  factor 
in  the  production  of  the  ataxic  movements  which  characterize  the  second  stage  of  the  disease. 

"The  vesical  and  rectal  reflexes  are  diminished  in  posterior  spinal  sclerosis.  Slow, 
irregular  micturition  is  complained  of  by  most  patients,  in  the  first  stage  and  in  the  sec- 
ond. We  usually  micturate  without  using  much  volition,  but  the  tabetic  patient  is  obliged 
to  strain  and  to  try  hard  to  pass  water.  Defecation  is,  like  micturition,  a  semi  voluntary 
act,  and  in  the  late  first  stage  of  the  disease  in  question  constipation  becomes  more  and 
more  marked,  and  that  through  loss  of  the  automatic  or  reflex  action  of  the  rectum  and 
adjacent  muscles. 

"  The  sexual  act  is,  in  my  experience,  frequently  impaired  and  sometimes  almost  lost 
before  the  second  stage  sets  in.  The  acts  of  erection  and  emission  are  usually  brought 
about  in  a  reflex  manner  by  irritation  of  the  skin  and  mucous  membrane  of  the  genitals. 
As  a  result  of  diminished  spinal  reflex  action  we  have  imperfect  erections,  and  either 


SYSTEMATIC  LESIONS  OF  KINESODIG  SYSTEM.         611 

the  posterior  columns  of  the  spinal  cord  have  sustained  the 
physiological  experiments  and  deductions  as  regards  the  prob- 
able function  of  these  parts.  We  have  found  that  sensation 
is  affected  in  various  ways  and  degrees  ;  that  coordination  of 
muscular  movement  is  interfered  with  in  the  advanced  stages 
of  the  destructive  process  ;  and,  finally,  that  the  reflex  func- 
tion of  the  spinal  cord  is  impaired,  when  the  sensory  nerves 
become  incapable  of  properly  transmitting  their  impulses  to 
the  motor  cells  of  the  cord. 

Several  theories  have  been  advanced  to  explain  the  devel- 
opment of  ataxic  symptoms,  all  of  which  will  help  to  fix  some 
anatomical  point,  previously  mentioned,  forcibly  in  your  mem- 
ories.    These  theories  may  be  thus  enumerated  : 

1.  That  the  destruction  of  the  comr^iissural  fibers  which 
connect  the  different  segments  of  the  cord  causes  ataxia. 

2.  That  the  tonic  action,,  which  is  claimed  to  be  normally  ex- 
erted by  the  spinal  cord  upon  the  muscular  tissues  of  the  body, 
is  impaired  ;  hence,  a  certain  unnatural  relaxation  of  some  parts 
exists,  which  induces  irregularity  of  muscular  movements. 

3.  That  the  condition  of  anaesthesia,  which  is  probably  pres- 
ent in  the  muscular  tissues  as  well  as  in  the  skin,  destroys  the 
so-called  ''-muscular  sense "/  hence,  the  patients  can  not  prop- 
erly guide  the  contractions  of  muscles. 

"SYSTEMATIC   LESIONS"   OF  THE   "KINESODIG   SYSTEM." 

As  has  been  stated  in  the  anatomical  description  of  the 
spinal  cord,  the  kinesodic  or  motor  regions  of  the  cord  include 

premature  emission,  or,  what  is  more  common,  I  believe,  very  slow  production  of  the 
orgasm,  and  impossibility  of  repetition  within  a  reasonable  time. 

"  Some  writers  admit  abnormally  great  sexual  power  in  the  early  stage  of  tabes,  but  I 
am  not  sure  to  have  met  with  more  than  one  or  two  cases  in  which  this  seemed  to  be  the 
case.  In  one  of  the  patients,  a  female,  I  became  convinced  that  her  extraordinary  ca- 
pacity for  sexual  intercourse  was  not  in  a  strict  sense  pathological  or  pre-tabetic,  but  had 
been  marked  in  one  shape  or  another  from  childhood. 

"  It  seems  reasonable  at  the  present  time  to  advance  this  general  proposition :  that,  in 
posterior  spinal  sclerosis,  the  various  reflex  actions  performed  by  means  of  those  portions 
of  the  coi'd  which  are  the  seat  of  sclerosis  are  diminished  or  lost ;  or,  to  put  it  in  another 
way  more  useful  for  practice,  it  may  be  said  that  the  limitations  of  loss  of  reflex  action  in 
different  parts  of  the  body  accurately  indicate  the  limits  of  sclerosis  in  the  posterior  sen- 
sory apparatus  in  the  spinal  axis." 


612  THE  SPINAL   CORD. 

tlie  columns  of  Turck '  (called  also  the  "  direct  pyramidal 
fasciculi  " ),  the  anterior  root  zones,  the  anterior  portion  of  the 
lateral  columns,  and  the  posterior  portion  of  the  lateral  col- 
umns (called  also  the  "crossed  pyramidal  fasciculi").  As 
indicated  in  the  table  of  diseases  of  the  spinal  cord,"  several 
distinct  and  separate  affections  of  these  component  parts  may 
exist,  each  of  which  presents  some  symptoms  which  are  spe- 
cially diagnostic. 

When  we  review  the  points  mentioned  as  to  the  func- 
tions of  the  kinesodic  system,  we  should  expect  to  lind  that 
any  lesion  confined  to  the  regions  designated  above  w^ould  be 
manifested  by  disturbances  in  the  motor  functions  of  the  body 
and  by  certain  "  trophic  changes  "/  while  we  should  also  ex- 
pect to  find  an  absence  of  any  disturbance  in  the  sensory  nerves 
or  in  the  coordination  of  movement.  This  is  fully  confirmed 
by  clinical  experience.  In  all  lesions  of  the  kinesodic  system, 
we  are  apt  to  meet  either  muscular  spasm,  muscular  atrophy, 
or  motor  paresis,  or  paralysis  ;  but  we  are  never  confronted 
with  fulgurating  pains,  numbness,  or  anaesthesia,  provided 
the  posterior  columns  (the  sesthesodic  system)  be  not  simulta- 
neously involved.  In  order  to  appreciate  the  points  of  diag- 
nosis of  the  different  forms  of  systematic  lesions  which  may 
affect  the  anterior  half  of  the  cord,  it  will  be  necessary  to  dis- 
cuss, in  a  general  way,  the  special  symptoms  of  each. 

SCLEROSIS   OF  THE   COLUMNS  OF  TURCK. 

The  columns  of  Tiirck  (*  the  direct  pyramidal  fasciculi  '*) 
are  affected  with  sclerosis,  either  separately  and  alone,  or  in 
connection  with  similar  changes  in  the  postero-lateral  columns 
("the  crossed  pyramidal  fasciculi").  What  its  producing 
causes  are  is,  as  yet,  not  thoroughly  understood.  We  simply 
know,  from  pathological  investigation,  that  sclerosis  of  the 

'  See  a  previous  page  of  this  volume. 

'  Tiirck  may  be  justly  considered  as  the  pioneer  in  the  investigation  of  systematie 
spinal  leaions,  since,  as  early  as  1851,  he  recognized  sclerosis  of  the  motor  columns  of  the 
cord  and  the  crossed  effect  of  brain  lesions  upon  the  motor  columns.  Much  valuable  re- 
search has  since  been  performed  by  Vulpian,  Bouchard,  Ficchsig,  Seguin,  Charcot,  and 
others. 


SCLEROSIS  OF  THE  COLUMNS  OF  TURCK. 


613 


two  portions  of  the  kinesodic  system  mentioned  is  liable  to 
occur  simultaneously,  although  they  may  be  individually 
affected.  We  also  know  that  disease  of  the  motor  tract  of 
the  crus,  above  the  decussation  of  the  motor  nerves  in  the  me- 
dulla, as  well  as  lesions  in  the  nucleus  caudatus,  the  internal 
capsule,  the  lobulus  para-centralis,  and  the  motor  regions  of 
the  cortex,  often  causes  what  is  termed  "  secondary  degenera- 
tion ' '  throughout  the  motor  tract  of 
the  spinal  cord  for  its  entire  length  ; 
hence,  this  condition  of  the  motor 
columns  may  be  the  late  result  of 
some  preceding  brain  lesion,  and  is 
most  marked  in  one  lateral  half  of 
the  cord  (most  commonly  on  the  half 
opposite  to  the  seat  of  the  exciting 
lesion  in  the  brain).  The  accompa- 
nying diagram,  which  illustrates 
the  course  of  the  fibers  in  the  me- 
dulla oblongata,  will  explain  why 
the  symptoms  produced  by  de- 
scending degeneration  of  the  motor 
columns  of  the  cord  are  not  always 
present  upon  the  opposite  side  of 
the  body  to  that  of  the  brain  lesion 
which  produced  it,  since  it  shows 
that  some  of  the  fibers  of  the  cord 
do  not  decussate. 

This  diagram  shows  that  the 
fibers  of  the  medulla  decussate  be- 
fore entering  the  spinal  cord,  for 
the  most  part,'  but  that  a  certain 
proportion  of  the  fibers  pass  in  a 
direct  line  from  the  encephalon  to 
the  cord.  The  figures  (shown  at 
the  bottom  of  the  diagram)  indicate  the  relative  proportion 


Fig.  181. — A  diagram  to  show  the  de- 
cussation of  motor  nerve  Jihers  in 
the  medulla  oblongata.  (After 
Flechsig  and  Seguin.) 

P.  v.,  pons  Varolii ;  M.  0.,  medulla 
oblongata ;  0,  olivary  body ; 
A.  P.,  anterior  pyramid  ;  D,  de- 
cussation; S.  C,  spinal  cord. 
The  direct  and  crossed  bun- 
dles vary  very  much  in  size,  as 
shown  in  the  following  ratios  oC 
crossed  and  direct:  (100  :  00), 
(92  :  8),  (84  :  16),  (70  :  30), 
(52  :  48),  (35  :  65),  (10  :  90). 


^  Much  of  our  present  knowledge  upon  this  point  is  due  to  the  researches  of  Flechsig  in 
1867,  and  to  those  of  Bouchard  in  1866,  made  in  connection  with  Vulpian  and  Charcot. 


614  TEE  SPINAL   CORD. 

between  the  direct  and  the  decussating  fibers,  which  have 
been  found  in  different  instances.  Now,  as  this  ''secondary- 
degeneration"  (caused  by  lesions  of  the  encephalon)  follows 
the  individual  nerve  fibers,  the  effects  would  be  manifested, 
for  the  most  part,  upon  the  opposite  side  of  the  body,  since 
most  of  the  fibers  decussate  ;  but  some  nerve  fibers,  which  do 
not  decussate,  would  be  impaired  on  the  same  side  of  the  spi- 
nal cord  as  the  existing  brain  lesion.  Thus  we  are  enabled  to 
explain  spinal  symptoms  on  both  sides  of  the  body,  when 
preceded  by  a  cerebral  lesion ;  although  the  spinal  manifes- 
tations are  usually  detected  on  the  side  opposite  to  the  excit- 
ing cause.  The  varying  proportion  of  these  direct  fibers  to 
those  which  decussate  will  explain  why  this  secondary  degen- 
eration may  be  followed  by  symptoms  confined  entirely  to 
one  side  of  the  body,  or,  again,  affecting  both  sides. 

You  are  probably  wondering  how  it  is  possible  to  tell 
when  this  slowly  progressing  degeneration  of  the  columns  of 
Tiirck,  or  of  the  postero-lateral  columns,'  is  present.  When 
an  attack  of  hemiplegia  has  occurred,  you  have  probably 
been  able  to  decide  early  whether  it  is  of  cerebral  or  spinal 
origin  ;  since,  if  cerebral,  it  will  probably  affect  the  side  of 
the  body  opposite  to  the  seat  of  the  lesion  within  the  brain, 
and  other  points  in  the  history  will  probably  confirm  this  as 
the  exciting  cause.  Some  time  after  the  attack  of  hemiplegia, 
however,  you  will  notice  that  the  paralyzed  muscles  are  be- 
coming more  or  less  rigid,  and  that  a  state  of  contracture  is 
developing.  Now,  it  is  this  point  in  the  case  that  should  in- 
dicate to  your  minds  the  fact  that  a  progressive  descending 
degeneration  of  the  spinal  cord  is  taking  place,  and  you  can 
safely  expect  to  find  sclerosis  of  the  anterior  and  postero-lat- 
eral columns  at  the  autopsy. 

In  some  cases  the  contracture  of  paralyzed  muscles,  after 
an  attack  of  hemiplegia,  is  accompanied  by  an  atrophy  of  the 
paralyzed  and  rigid  muscles ;  so  that  their  volume  becomes 
much  more  extensively  impaired  than  would  ensue  from  sim- 


*  Our  present  knowledge  leads  us  to  infer  that  the  anterior  and  lateral  columns  pos- 
B  a  sirailaritv  of  function. 


J 


SCLEROSIS  OF  THE  LATERAL   COLUMNS.  615 

pie  disuse.  In  this  event,  you  may  be  justified  in  suspecting 
that  the  anterior  horns  of  the  gray  matter  of  the  spinal  cord 
are  becoming  diseased,  a  condition  to  which  the  tenn  "  polio- 
myelitis," or  "  myelitis  of  the  anterior  horns,"  may  be  found 
applied  in  treatises  upon  nervous  diseases.  This  will  be  con- 
sidered in  detail  in  a  subsequent  lecture. 

SCLEROSIS   OF   THE    LATERAL   COLUMNS    {''  TETAN^OID   PARAPLEGIA  '* — 
*^  SPASMODIC   TABES"). 

The  lateral  columns  (including  the  whole  of  the  mass  of 
white  substance  found  at  the  sides  of  the  spinal  cord)  may  be 
diseased,  either  as  a  primary  lesion,  following  cold,  damp- 
ness, over-exertion,  and  syphilis,  or  as  a  part  of  a  secondary 
morbid  process  (chiefly  in  connection  with  polio-myelitis). 
In  1875  the  name  of  ^'spastic  spinal  paralysis"  was  applied 
to  this  condition  by  Erb,'  and  in  1876  Charcot'  described  it 
under  the  head  of  "spasmodic  tabes."  You  will,  therefore, 
find  it  described  under  both  of  these  names,  although  I  prefer 
the  name,  applied  to  it  by  my  friend  Professor  Seguin,  "  teta- 
noid paralysis  or  paraplegia,"  since  to  the  common  mind  it 
best  conveys  the  idea  of  its  symptomatology. 

As  this  lesion  is  often  combined  with  myelitis  of  the  ante- 
rior horns  of  gray  matter,  as  mentioned  above,  and  since  such 
degeneration  of  the  anterior  horns  is  apt  to  affect  the  "trophic 
function "  of  the  cord,  Charcot  has  applied  to  this  complex 
systematic  affection  of  the  cord  the  term  "  amyotrophic  lateral 
sclerosis."  A  peculiarity  of  sclerosis  of  the  lateral  columns 
of  the  cord,  whether  complicated  with  disease  of  the  anterior 
horns  or  not,  is  that  both  sides  of  the  spinal  cord  are  nearly 
always  involved  at  the  same  time  ;  hence,  the  occurrence  of 
paraplegia  is  more  strongly  diagnostic  of  this  affection,  pro- 
vided other  symptoms  of  value  exist,  than  if  hemiplegia  be 
present.  I  shall  use  the  term  "tetanoid  paraplegia,"  there- 
fore, in  preference  to  the  other  names  suggested  by  the  au- 
thors quoted,  in  describing  the  symptoms  which  are  diag- 
nostic of  this  affection. 

*  Op.  CU.  2  Qp  cit. 


616  THE  SPINAL   CORD. 

When  the  sclerosis  of  the  lateral  columns  affects  the  cerm- 
cal  enlargement  of  the  spinal  cord  (where  the  nerves  to  the 
upper  extremities  are  given  off),  the  symptoms  appear  first  in 
the  hands.  The  affected  parts  have  a  peculiar  sense  of  formi- 
cation, like  the  creeping  of  ants  over  the  part.  They  undergo 
rapid  atrophy  (if  the  anterior  horns  are  affected '),  causing 
the  hands  to  become  bony  from  disappearance  of  the  inter- 
ossei  muscles,  and  the  parts  become  simultaneously  para- 
lyzed. Soon  a  contracture  of  the  paralyzed  muscles  develops, 
producing  the  so-called  '*  claw-hand  deformity."  The  lower 
limbs  become  at  first  paretic,  but  gradually  develop  a  para- 
lyzed and  contractured  condition  ;  although  the  contractured 
state  of  the  muscles  is  very  much  more  apparent  when  the 
patient  stands  and  attempts  to  walk  than  when  lying  in  bed, 
since  the  rigidity  almost  disappears  when  in  the  recumbent 
position.  If  the  lesion  extend  upward  to  the  region  of  the 
motor  bulbar  nerves,  the  symptoms  of  glosso-labio-laryngeal 
paralysis "  may  be  developed,  in  addition  to  the  other  symp- 
toms described.  The  muscles  of  the  legs  do  not  generally 
waste,  and  the  bladder  and  rectum  are  not,  as  a  rule,  para- 
lyzed. No  evidences  of  anaesthesia  can  be  usually  discovered 
in  the  regions  affected. 

In  tetanoid  paraplegia,  there  is  a  marked  increase  in  the 
reflex  excitability  of  the  affected  parts.  It  is  to  this  increase 
in  all  the  reflex  movements  that  the  peculiar  gait  of  this  class 
of  patients  may  be  attributed.  Thus,  the  increased  action  of 
the  adductor  muscles  tends  to  make  the  legs  almost  cross  each 
other  in  walking ; '  the  excessive  action  of  the  muscles  of  the 
calf  raises  the  heel,  and  the  legs  move  with  a  stiffness  which 
makes  a  contrast  with  the  normal  act  of  walking.  In  the  last 
stages  of  this  affection,  when  the  patient  becomes  bedridden, 

'  A  complex  condition,  termed  by  Charcot  "  amyotrophic  lateral  sclerosis."  The  pa- 
tient (when  the  legs  become  affected)  at  first  walks  with  a  cane,  then  with  crutches,  and 
later  on  requires  an  attendant. 

^  The  symptoms  of  this  affection  (Duchenne's  disease)  have  been  given  in  detail  in 
connection  with  the  hypo-glossal  nerve.  The  reader  is  referred  to  page  525  of  this 
volume. 

^  When  both  the  lower  limbs  are  affected  by  lesions  of  the  lateral  columns  of  the 
cord,  the  legs  frequently  become  interlocked  at  every  attempt  to  walk. 


TETANOID  PARAPLEGIA.  617 

the  increased  reflex  excitability  causes  the  legs  to  become 
semi-flexed  and  adducted,  and  the  muscles  are  sensibly  hard- 
ened. It  is  a  clinical  point  of  some  value  that  the  muscles 
affected  with  tetanoid  paraplegia  retain  their  noraial  size,  nu- 
trition, and  electrical  reactions  (provided  that  the  anterior 
horns  are  not  diseased).  This  condition  is  quite  commonly 
met  with  in  children  ; '  and  the  little  sufferers  can  not  often 
stand  or  walk,  from  the  spasmodic  action  of  the  muscles  of  the 
legs.  In  adults,  as  a  further  evidence  of  the  increased  reflex 
excitability  of  parts,  the  act  of  passing  the  urine  or  faeces  be- 
comes one  which  requires  the  patient  to  hurry  with  all  possible 
speed,  in  order  to  avoid  a  sudden  and  involuntary  evacuation. 
Now,  the  absence  of  anaesthesia,  of  numbness,  and  of  ful- 
gurating pains,  will  easily  assist  you  to  diagnose  between  a 
case  of  disease  of  the  posterior  columns  and  that  of  the  lat- 
eral columns  of  the  cord,  although  the  peculiarity  of  gait 
may  for  a  while  confuse  you.  The  increase  in  the  ''patellar 
reflex  " '  and  the  actual  loss  of  power  of  individual  muscles 
will  also  assist  you  in  the  diagnosis  ;  while  in  tetanoid  para- 
plegia the  muscles  are  stiffened,  especially  when  standing  or 
walking,  sensations  are  not  delayed,  and  coordination  of 
movement  is  normally  performed. 

MYELITIS    OF    THE    AN^TERIOR    HORNS    ("ATROPHIC    SPINAL 
PARALYSIS  "). 

As  shown  in  the  table  ^  of  diseases  which  may  affect  the 
kinesodic  system  of  the  spinal  cord,  the  anterior  horns  of  gray 
matter  may  be  the  seat  of  degeneration.  As  in  all  other  le- 
sions of  the  motor  tract  of  the  cord,  the  symptoms  of  this 
affection  are  confined  to  motor  phenomena,  and  characterized 
by  the  absence  of  sensory  effects  (anaesthesia,  numbness, 
etc.) ;  but,  in  addition  to  the  motor  phenomena,  certain  tro- 

^  These  children  are  often  microcephalic  or  idiotic ;  hence  the  symptoms  may  be  due 
to  an  incomplete  development  of  the  motor  tract  of  the  spinal  cord.  It  is  stated  by  Se- 
guin  that  circumcision  can  not  be  considered  as  a  curative  measure  in  all  cases,  since 
Jewish  children,  circumcised  at  birth,  have  been  frequently  seen  by  him  with  typical  evi- 
dences of  this  disease. 

2  See  page  609  of  this  volume.  ^  See  page  601  of  this  volume. 


618  THE  SPINAL   CORD. 

pMc  changes  become  prominently  developed,  which  are  of 
special  value  to  the  diagnostician. 

In  this  lesion  we  find,  after  death  has  occurred,  that  the 
motor  cells  of  the  cord  have  undergone  atrophy  (due,  prob- 
ably, to  an  acute  inflammatory  degeneration  associated  with 
pigmentation  of  the  parts),  and  that  the  anterior  roots  of  the 
spinal  nerves  have  likewise  undergone  a  fatty  metamorphosis. 
The  condition  may  be  of  three  distinct  types,  which  are  called 
the  acute,  sub-acute,  and  chronic  varieties,  and  each  presents 
certain  characteristic  symptoms.  The  term  '''' polio-myelitis^' 
is  frequently  used  as  a  synonym  for  this  change  in  the  ante-^/ 
rior  horns.  X 

The  acute  form  is  manifested  by  the  presence  of  a  fever, 
either  of  the  continued  or  remittent  type,  which  is  usually  ac- 
companied by  pains,  and  a  sense  of  numbness  in  the  limbs. 
As  the  fever  subsides,  usually  in  the  course  of  several  days, 
an  extensile  paralysis  is  suddenly  developed.  This  paralysis 
may  affect  both  arms  and  both  legs,  the  legs  alone,  or,  pos- 
sibly, only  one  of  the  four  extremities  ;  it  may  occasionally  be 
a  hemiplegia,  if  one  side  of  the  cord  is  alone  involved.  In  a 
longer  or  shorter  space  of  time,  this  paralysis  gradually  dimin- 
ishes ;  the  bladder  and  rectum  remain  unimpaired  throughout 
the  attack  of  paralysis ;  no  anaesthesia  or  numbness  can  be 
detected  in  the  paralyzed  parts ;  and  there  is  no  tendency  to 
the  development  of  bed-sores.  If  you  test  the  paralyzed 
limbs  for  reflex  movements,  you  will  usually  find  them  totally 
abolished.*  If  you  apply  the  faradic  current,  the  muscles 
will  fail  to  respond  ;  but,  when  the  constant  current  is  used^p" 
you  will  notice  a  slow  contraction,  and  certain  variations  in 
the  usual  formulae  of  galvanic  reaction  will  stamp  the  condi- 
tion as  one  of  degeneration.'    What  these  formulae  are  can  bcP 

*' ' 

'  This  is  not  always  the  case,  as  the  reflex  movements  are  oftentimes  only  decrease^' 
in  frequency  and  force. 

«  "  Remarkably  distinct  evidences  of  the  dci^enerative  reaction  to  electricity  are  ob- 
tained from  the  second  to  the  tenth  week.  The  nerve  trunks  supplying  the  paralyzed 
muscular  groups  lose  their  excitability  to  faradism  and  galvanism,  and  these  wasting 
muscles  react  only  to  galvanism,  and  their  reaction  formula  is  altered  from  the  normal ; 
in  general  terms,  we  may  say  that  An  c  c  =  Ka  c  c,  or  even  An  c  c  >  Ka  c  c ;  and  all  con- 
tractions are  slow  and  wave-like."    (E.  C.  Seguin,  "Med.  Record,"  1878.) 


MYELITIS   OF  THE  ANTERIOR  HORNS, 


619 


easily  found  in  any  of  the  special  treatises  on  the  treatment 
and  diagnosis  of  nervous  affections.  Now,  in  this  type  of 
myelitis,  you  will  not  have  to  wait  long  to  decide  as  to  its 
character.  In  a  few  days  or  weeks  the  muscles  of  the  para- 
lyzed limbs  will  show  a  rapid  wasting,  since  the  muscles  are 
undergoing  atrophy ;  and  this  wasting  is  markedly  progres- 
sive, since  the  change  in  the  muscles  continues  to  extend  until 
a  most  characteristic  and  permanent  deformity  results,  pro- 
vided that  recovery  does  not  occur. 

This  condition  of  the  cord  is  frequently  associated  with 
sclerosis  of  the  lateral  columns  ;  hence,  it  is  not  infrequent  to 
observe  a  state  of  contraction  in  the  paralyzed  muscles,  which 
lasts  in  a  varying  degree,  until  the  atrophy  of  the  contractured 
muscles  destroys  their  power  of  producing  deformity.  These 
contractions  are  not  inevitably  permanent,  if  present  in  the 


Fig.  182. — Amyotrophic  lateral  sclerosis^  with  contracture.    (Charcot.) 


early  stages  of  the  disease,  as  they  may  totally  disappear  in 
exceptional  cases ;  but  they  usually  return  with  increased 
deformity  as  the  disease  progresses. 

In  cases  of  so-called  ''infantile  spinal  paralysis,"  and  in 
similar  cases  affecting  the  adult,  a  non-febrile  variety  of  this 
affection  may  be  met  with,  where  the  disease  begins  with  no 
initial  symptoms,  but  where  the  paralysis  and  all  subsequent 
symptoms  mentioned  above  are  developed  suddenly. 


620  "  THE  SPmAL   COBD. 

The  chronic  form  of  myelitis  of  the  anterior  horns  is  sel-  1 

dom  to  be  diagnosed  from  progressive  muscular  atrophy.     It  | 

is  claimed  that  the  severe  neuralgic  pains  which  accompany  i 

the  wasting  process  of  the  former  are  diagnostic  between  the  , 

two  affections,  and  that  the  degeneration  of  the  affected  parts  ] 

does  not  assume  t\iQ  fibrillary  ot fascicular  character  of  true  j 

progressive  atrophy,  dependent  upon  changes  confined  to  the  ''■ 

ganglion  cells  of  the  spinal  cord,  but  the  distinction  is,  in  my  ; 

experience,  a  difficult  one.  ; 

The  condition  of  polio-myelitis  tends,  as  a  rule,  to  progress  i 

upward  along  the  spinal  cord,  and  thus  often  reaches  the  me-  ; 

dulla  oblongata.     The  symptoms  which  are  then  produced  in-  ; 

elude  those  of  paralysis  and  atrophy  of  the  tongue,  difficult  ] 

deglutition,  impairment  of  speech,  and  a  nasal  quality  of  the  \ 

voice,  due  to  the  paralysis  of  the  soft  palate.     The  expression  \ 

of  the  face  is  greatly  altered  by  paralysis  of  the  orbicularis  \ 

oris  muscle,  which  creates  an  apparent  increase  in  the  width  ; 

of  the  mouth  ;  and,  after  laughing  or  weeping,  the  mouth  re-  j 

mains  open  for  an  unusual  period,  and  thus  favors  the  escape  i 

of  saliva.  , ) 

'a 

PKOGRESSIVE     MUSCULAR    ATROPHY     (DEGEN^ERATIGN"     OF    THE    GAN-  \ 

GLTON   CELLS   OF  THE   AN^TERIOR  HORN^s).  '■    ^^ 

Degeneration  of  the  ganglion  cells  of  the  anterior  horns  of  j 

the  cord  is  pathologically  distinguished  from  the  condition  just  j 

described,  since  the  results  of  the  former  were  of  an  inflam-  \ 

matory  character,  while  the  latter  is  a  purely  degenerative  i 

process  of  primary  origin.    The  former  was  rapid  in  its  effects  ;  < 

this  disease  is  slow,  since  the  ganglion  cells  undergo  molecular  i 

disintegration.     We  may  expect  to  find,  at  the  autopsy  of  ' 

such  a  case,  the  cells  changed  into  a  granular  condition,  and  \ 

more  or  less  destroyed  ;  while,  in  extreme  cases,  the  anterior  j 

horns  of  gray  matter  of   the  affected  part  may  be  utterly  I 

destitute  of  these  cells.  \ 

It  is  this  pathological  change  that  creates  the  train  of  j 

symptoms  called  '*  progressive  muscular  atrophy."    The  mus-  \ 

cles,  supplied  by  nerves  connected  with  the  seat  of  degener-  \ 


ii^Li 


PROGRESSIVE  MUSCULAR  ATROPHY. 


621 


ation,  begin  to  show  a  slowly  developing  atrophy  of  certain 
fibers  or  bundles,  while  other  parts  of  the  muscle  may  ap- 
pear perfectly  normal ;  thus  it  may  take  months  for  an  entire 
muscle  to  become  completely  wasted, 
the  muscle  showing  during  its  con- 
traction the  gradual  atrophy  of  cer- 
tain parts.  This  disease  seems  to  exist 
most  commonly  in  the  muscles  of  the 
hand,  thighs,  and  chest,  and  a  symme- 
try '  in  its  development  is  a  character- 
istic feature.  It  is  seldom  associated 
with  any  sensory  symptoms.  In  the 
rarest  cases  will  yon  be  able  to  detect 
the  existence  of  pain  ; "  and  symptoms 
of  anaesthesia  are  wholly  absent.  An- 
other point  which  will  assist  you  in 
diagnosis  is  the  absence  of  paralysis ; 
although  the  affected  muscles  may  show 
a  loss  of  power  in  proportion  to  the  ac- 
tual destruction  of  muscular  tissue.  If 
you  apply  the  faradic  current  to  the 
affected  muscles,  you  will  find  that  they 
respond  to  its  influence  in  exact  pro- 
portion to  the  extent  of  the  degenera- 
tion, so  that  the  unaffected  fasciculi 
will  be  thrown  into  contraction.  This 
is  in  marked  contrast  to  the  effect  of 
the  faradic  current  upon  the  muscles  in 
the  case  of  myelitis  of  the  anterior 
horns,  where  the  muscles  failed  to  re- 
spond in  their  entirety,  even  before  they  showed  any  evidence 
of  atrophy. 

The  muscles  which  are  undergoing  the  early  changes  of 


Fig.  183. — Progressive  rmts- 
cular  atrophy  of  upper 
extremity.    (Hammond.) 


'  The  atrophy  affects  parts  which  are  not  only  symmetrical^  but  homologous.  It  is 
common  to  see  both  shoulders  simultaneously  atrophied,  or  the  arms  and  thighs,  or  the 
forearms  and  the  legs. 

2  Hammond  states  that  pain  is  perceived  after  exertion,  but  he  attributes  it  to  muscular 
fatigue  rather  than  to  central  causes. 
42 


THE  SPINAL   CORD. 


this  wasting  are  the  seat  of  what  are  CBlledflbrillary  contraa*  '^ 
tions.'    These  are  produced  by  the  involuntary  rapid  contrac-     ] 


Fig.  184. — Progressive  nmscular  atrophy.    Age  of  patient^  forty-Jive  years.    (From  Fried- 
reich.) 

tions  of  fasciculi  of  fibers  in  a  muscle.  Sometimes  a  patient 
is  covered  with  them.  Some  years  ago,  these  fibrillary  con- 
tractions were  held  to  be  pathognomonic,  but  I  can  assure 
you  that  this  is  not  so,  as  they  may  be  observed  in  lead  palsy, 

'  These  peculiar  twitchings  give  the  appearance  of  something  alive  being  underneath 
the  skin.  Hammond  states  that  "  they  can  always  be  excited  by  a  smart  tap  of  the  fin- 
ger upon  the  atrophied  muscle." 


PROGRESSIVE  MUSCULAR  ATROPHY.  623 

in  conditions  of  neurasthenia,  and  in  simple  paralysis.  In- 
deed, many  years  ago  Professor  Schiff,  now  of  Geneva,  showed 
that  muscles  separated  from  their  motor  nerves  were  prone  to 
show  fibrillary  contractions. 

The  hall  of  the  thumb  is  often  the  starting-point  of  this 
disease.  For  some  reason,  the  muscles  of  the  foot  are  not  af- 
fected in  the  same  proportion,  in  those  cases  where  the  lower 
extremity  is  involved,  as  the  hand  is  in  cases  affecting  the 
upper  extremity.  In  some  instances,  every  muscle  in  a  region 
but  one  may  be  atrophied,  and  that  one  seem  to  remain  per- 
fectly normal.  If  you  use  a  surface  thermometer,  you  will 
generally  detect  a  fall  of  temperature  over  the  affected  mus- 
cles.' When  the  respiratory  muscles  become  involved,  death 
may  be  produced  from  imperfect  performance  of  that  func- 
tion. The  disease  seems  to  affect  males  rather  than  females, 
and  to  be  most  frequent  during  middle  life.  It  is  sometimes 
associated  with  a  congenital  predisposition.'* 

The  muscles  of  the  thigh  are  frequently  affected  with 
atrophy,  following  degeneration  of  the  ganglion  cells  of  the 
anterior  horns  of  the  spinal  gray  matter.  This  causes  not 
only  a  very  marked  deformity  (since  the  calf  may  even  ex- 
ceed the  thigh  in  its  circumference),  but  a  peculiarity  of  gait 
is  thus  produced  which  differs  from  those  described  in  con- 
nection with  locomotor  ataxia,  tetanoid  paraplegia,  and 
paresis. 

If  the  extensor  muscles,  which  are  situated  upon  its  an- 
terior portion,  are  atrophied,  the  foot  can  not  be  carried  for- 
ward in  the  normal  manner,  if  at  all ;  while  the  leg  and  foot 
can  not  be  raised,  if  the  flexor  muscles  of  the  knee  joint  be 
impaired  by  an  atrophy  confined  to  the  posterior  aspect  of 
the  thigh,  thus  compelling  the  psoas  and  iliacus  muscles  to 
lift  the  weight  of  the  entire  upper  extremity  by  using  the 
pelvis  as  a  fixed  point. 

*  Hammond  reports  this  fall  in  temperature  as  often  reaching  five  degrees  below  the 
normal  standard. 

^  See  the  careful  investigations  made  by  Hammond,  and  reported  by  him  in  his  excel- 
lent work,  "  A  Treatise  on  the  Diseases  of  the  Nervous  System."  New  York :  D.  Apple- 
ton  &  Co.,  1886. 


624  THE  SPINAL   CORD. 

Distortions  of  tlie  affected  members  often  accompany  the 
condition  of  progressive  muscular  atrophy.  These  are  to  be 
accounted  for  by  the  fact  that  a  simultaneous  impairment  of 
all  the  muscles  seldom  occurs,  and  those  antagonistic  to  the 
ones  affected  tend  to  produce  an  abnormality  of  attitude  in 
the  part  upon  which  they  both  acted  in  health. 

CENTRAL  MYELITIS. 

Among  the  diseases  of  the  kinesodic  system  may  be  men-  | 

tioned  the  condition  known  as  "central  myelitis."     In  this  ' 

affection,  the  gray  matter  of  the  cord  is  the  seat  of  a  chronic  j 

type  of  inflammation  in  its  central  portion ;  hence,  it  may  ; 
involve  either  the  kinesodic  or  the  sesthesodic  system.     The 

inflammatory  process  may  extend  to  the  anterior  horns,  or  ' 

may  create  compression  of  the  cord,  in  almost  any  portion,  by  \ 

the  exudation  which  results.     The  symptoms  of  this  disease  I 

must,  therefore,  of  necessity,  vary  with  the  seat  of  the  patho-  ' 

logical  changes,  and,  in  some  cases,  be  very  obscure  and  appa-  ■ 

rently  confusing  to  the  diagnostician.    We  may  have  the  man-  \ 

ifestations  confined,  for  a  time,  to  the  sensory  nerves,  possibly  , 

accompanied  by  pain,  numbness,  anaesthesia,  formication,  etc.  i 

Gradually  certain  manifestations  will  appear  in  the  motor  ; 

nerves,  and  paralysis  of  certain  muscles  and  possible  atrophy  ; 

may  be  developed.     The  reflex  action  may  be  increased  in  \ 

some  parts  and  diminished  in  others,  according  to  the  portion  ^ 

of  the  gray  matter  involved ;  bed-sores  and  paralysis  of  the  j 

bladder  and  rectum  may  be  present  in  some  cases,  and  absent  ! 

in  others ;  the  legs  may  be  anaesthetic,  and  at  the  same  time  i 

paralyzed  ;  so  may  the  arms,  without  the  legs,  or  both  may  be  | 

thus  affected ;  certain  parts  may  have  the  tetanoid  condition  ' 
described  in  a  previous  portion  of  this  lecture  ;  and,  in  fact, 
every  known  combination  of  sensory  and  motor  symptoms 
may  be  present,  complicated  or  uncomplicated  by  the  evi- 
dences of  muscular  rigidity.  You  can  thus  understand  that 
the  disease  is  seldom  recognized  in  its  early  stage,  and,  as  it 
often  takes  years  to  reach  a  full  development,  an  abundant 
opportunity  will  generally  be  afforded  you  for  a  careful  and 


NON-SYSTEMATIC,  OR  ''FOCAL''  LESIONS.  625 

close  analysis  of  the  symptoms  which  are  successively  brought 
to  your  notice.' 

"NON-SYSTEMATIC"    OR    "FOOAL    LESIONS"    OF    THE    SPINAL 

CORD. 

We  have  now  considered,  in  this  course  of  lectures  upon 
the  spinal  cord,  those  lesions  which  are  called  ''systematic," 
since  they  tend  to  extend  upward  or  downward  in  the  same 
column  of  the  cord  without  spreading  laterally ;  and  it  now 
remains  for  us  to  review  such  points  as  pertain  to  those  focal 
or  non- systematic  lesions  which  have  been  enumerated  in  the 
table  of  diseases  of  the  spinal  cord.  It  is  often  possible  and 
of  great  practical  importance  to  the  diagnostician  to  tell  in 
what  region  of  the  cord  the  lesion  is  situated,  and  to  estimate 
the  height  to  which  it  has  progressed.  Of  course,  this  is 
much  easier  in  focal  lesions  than  in  the  systematic,  since  the 
different  columns  of  the  cord  can  then  simultaneously  fur- 
nish symptoms  which  can  be  compared,  and  thus  aid  in  the 
diagnosis.  If  you  will  look  again  at  the  table,''  to  which  I 
some  time  ago  directed  your  attention,  you  will  perceive  that 
the  focal  lesions  include  traumatisms  (of  all  forms) ;  compres- 
sion of  the  cord  (chiefly  by  bone  and  tumors) ;  transverse  scle- 
rosis of  the  cord ;  transverse  softening  of  the  cord ;  haemor- 
rhage into  the  substance  of  the  cord ;  and,  finally,  certain 
tumors  which  involve  the  cord  itself.  There  are  many  other 
causes  which  might  excite  some  local  lesion,  but  these  are  the 
ones  which  will  most  frequently  come  uilder  the  notice  of  the 
practitioner. 

Before  we  begin  the  study  of  the  symptoms  produced 
by  lesions  at  different  heights  in  the  spinal  cord,  it  may  be 
well  to  glance  hastily  at  the  drawing  which  I  have  made  for 
you  upon  the  blackboard,  copied  from  one  made  by  Seguin 
from  the  text  of  Malgaigne,  which  is  so  simple  and  diagram- 

'  The  valuable  contributions  of  Hallopeau,  in  the  "  Archives  G^nerales  de  Medecine," 
1872,  added  much  to  the  knowledge  of  this  obscure  affection.  Schiippel,  Westphal,  and 
Leyden  have  also  been  prominent  as  investigators  of  this  rather  rare  form  of  disease. 

'  See  page  601  of  this  volume. 


626 


THE  SPINAL   CORD. 


matic  as  to  illustrate  certain  points  of  great  clinical  value  and 
importance. 

Now,  if  you  will  look  at  this  diagram,  you  will  perceive 
that  the  line  upon  the  left  represents  the  different  levels  of 


Medulla. 


Axis.  < 

8dC.  V.  •< 

,1    \  Gth  0.  V.  <^ 

7th  C.V.  <( 

2dD.  V.  / 


11th  D  V.  <; 

12th  D.  V.  <^ 

1  L.  V.  <; 

2  L.  V.  <; 


Hypo-glossal  N. 

Pneumogastric  N. 
Phrenic  N. 

.  Brachial  plexus. 
Ulnar  nerve. 


.  Crural  N. 


Sciatic  N. 


FiQ.  186. — A  diagram  shoioing  the  rdaiion  of  the  spinoits  processes  of  the  vertehrcs  to  the 
spinal  nerves  and  spinal  cord.    (Malgaigne  and  Seguin.) 

the  spines  of  the  vertebrae,  and  that  the  special  points  in  the 
cord,  as  well  as  the  points  of  origin  of  certain  of  the  more  im- 
portant nerves,  are  likewise  shown.  You  will  observe  that 
the  hypo-glossal  and  the  pneumogastric  nerves  arise  from  the 
medulla,  which  lies  above  the  level  of  the  axis  ; '  that  the 
phrenic  arises  on  a  level  with  the  spine  of  the  axis  ;  that  the 
brachial  plexus  and  the  ulnar  nerve  are  connected  with  the 

*  This  drawing  illustrates  the  fact  that  the  spines  of  the  respective  vertebrae  do  not 
always  correspond  to  the  level  of  the  nerves  which  escape  from  between  their  pedicles. 


FOCAL  LESIONS  OF  THE  SPINAL   CORD.  627 

cord  in  the  region  of  the  neck  (third  to  sixth  cervical  spines)  ; 
that  the  cilio-spinal  center  is  situated  between  the  fifth  cervi- 
cal and  the  second  dorsal  vertebrae  ;  that  the  lumbar  enlarge- 
ment of  the  cord  gives  off  the  crural  and  sciatic  nerves  at 
different  points,  and  that  the  space  between  the  eleventh  dor- 
sal and  the  second  lumbar  spines  includes  the  point  of  origin 
of  both  ;  finally,  that  the  spinal  cord  ends  at  the  second  lum- 
bar spine,  although  the  nerves  continue  to  escape  from  the 
spinal  canal  much  below  that  point.  Such  a  diagram  will 
prove  of  constant  service  to  you,  in  following  the  discussion 
of  the  symptoms  of  focal  lesions  situated  at  different  heights 
within  the  spinal  cord. 

We  have  already  studied  the  effects  of  systematic  lesions, 
both  of  the  kinesodic  and  sesthesodic  systems,  and  have 
noticed  how  perfectly  the  physiology  of  the  spinal  cord  is 
confirmed  by  lesions  affecting  the  anterior  or  posterior  por- 
tions of  the  cord  separately.  We  are  now  to  investigate 
those  lesions  which,  by  extending  in  a  transverse  direction, 
are  liable  to  be  accompanied  by  symptoms  referable  to  both 
the  sensory  and  motor  portions  of  the  cord.  Of  course,  the 
symptoms  will  be  modified  by  the  extent  of  the  lesion  in  a 
transverse  direction,  so  that  they  may  be  mostly  sensory  or 
motor  ;  but  the  presence  of  both  sensory  and  motor  symp- 
toms is  strongly  diagnostic  of  focal  lesions,  irrespective  of  a 
predominence  of  either,  and  is  never  produced  by  any  sys- 
tematic lesion  of  the  cord,  with  the  one  exception  of  central 
myelitis. 

We  will  start  with  a  general  statement,  as  a  guide  in  our 
study  of  focal  lesions,  which  is  as  follows  :  focal  lesions  usu- 
ally give  rise  to  paralysis  of  motion,  to  an  alteration  in  the 
reflex  excitability  of  the  cord  (usually  an  increase),  and  to 
more  or  less  ancBstJiesia,  numbness,  and  pain ;  the  bladder 
and  rectum  are  often  paralyzed,  and  a  tendency  to  bed-sores 
is  frequently  produced.  The  first  two  of  these  effects,  and 
also  the  last,  are  due  to  alteration  in  the  kinesodic  system  ; 
the  remaining  ones  are  the  result  of  some  disturbance  to  the 
sesthesodic  system. 


628  THE  SPINAL   CORD. 

In  studying  focal  lesions  situated  in  different  regions  of 
the  spinal  cord,  we  must  adopt  some  system,  if  we  expect  to 
grasp  the  fine  distinctions  which  can  be  drawn  between  the 
results  of  lesions  of  the  upper  cervical  region,  the  cervical  en- 
largement, the  mid-dorsal  region,  the  region  just  above  the 
lumbar  enlargement,  and,  finally,  the  lumbar  enlargement 
itself.  Most  of  these  distinctions  depend  upon  certain  ana- 
tomical points.,  which  your  previous  drill  will  enable  you  to 
appreciate  more  easily  than  if  your  anatomical  knowledge 
had  become  deficient  from  a  lack  of  review. 

FOCAL  LESION  IN^  THE  UPPER  CERVICAL  REGION". 

In  this  condition,  hemiplegia  will  be  produced  if  one  lat- 
eral half  of  the  cord  be  alone  affected,  while  paraplegia  will  be 
present  if  the  lesion  extends  transversely  to  both  lateral  halves 
of  the  cord.  The  hemiplegia  or  paraplegia  will  be  complete 
below  the  head,  and  the  entire  body  may  be  rendered  anaes- 
thetic. Since  the  phrenic  nerw  arises  at  this  point,  the  act  of 
respiration  will  be  interfered  with,  creating  dyspnoea  and  hic- 
cough ;  but  the  respiration  will  not  be  arrested,  since  the 
pneumogastric  nerves  continue  to  excite  it,  and  the  auxiliary 
muscles  of  respiration  can  expand  the  chest  without  the  action 
of  the  diaphragm.  Should  the  lesion  be  a  surgical  one  (as  it 
usually  is),  the  respiratory  center  of  the  medulla  may  be  af- 
fected, and  death  take  place  from  asphyxia ;  but  I  do  not 
think  such  a  result  can  be  explained  as  a  simple  effect  of  pa- 
ralysis of  the  phrenic  nerves  alone.  The  presence  of  the  cilio- 
spinal  center  in  the  lower  cervical  region  may  cause  the  pu- 
pils to  show  an  irregularity,  and  the  face  and  neck  may  mani- 
fest a  marked  increase  of  temperature.*  The  pulse  may  be 
rendered  variable,  from  irritation  of  or  pressure  upon  the  ac- 
celeratory  center  of  the  heart. 

Now,  as  I  have  before  said,  this  type  of  lesion  is  almost  al- 
ways a  surgical  one,  comprising  pressure  from  fracture,  dislo- 
cation, caries,  tumors  of  the  vertebrae,  etc.,  and  these  cases 

'  See  page  380  of  this  volume  for  effects  of  blood-vessels  upon  the  iris ;  and  also  page 
381  for  the  evidences  of  diminished  iritic  reflex. 


FOCAL  LESIONS  OF  THE  CERVICAL  REGION.  629 

seldom  live  long  enough  for  us  to  study  the  effects  of  such  a 
lesion  with  much  detail.  In  those  rare  instances  where  the 
lesion  is  non-traumatic  and  slowly  developed,  the  effects  of 
irritation  have  been  shown  in  a  hiccough  (probably  due  to 
irritation  of  the  phrenic  nerve),  acceleration  of  the  pulse 
(from  irritation  of  the  acceleratory  center  of  the  heart),  and 
dyspnoea  (from  some  interference  with  the  phrenic  nerve  or 
the  nucleus  of  the  pneumogastric  nerve  in  the  medulla) ; 
while  the  paralysis  has  first  appeared  as  a  paretic  condition 
of  the  arms,  then  of  the  chest,  and,  finally,  of  the  lower  limbs. 

FOCAL  LESIOXS  OF  THE   CERVICAL  EKLARGEMENT. 

This  type  of  lesion  differs  in  its  effects,  if  developed  sud- 
denly or  gradually,  and  also  when  situated  in  the  upper  or  the 
lower  part  of  the  enlargement.  If  the  lesion  be  so  situated  as 
to  create  only  irritation  of  the  cilio-spinal  center,  or  the  ac- 
celeratory center  for  the  heart  (both  of  which  are  in  that  vicin- 
ity), the  effects  will  differ  from  those  due  to  actual  pressure 
upon  or  destruction  of  those  centers.'  In  the  first  instance, 
the  pupils  will  usually  be  dilated  and  the  face  pale,  while 
the  heart  will  be  accelerated ;  in  the  latter,  the  pupils  will 
generally  be  contracted,  the  face  and  neck  flushed,  and  the 
pulse  retarded.  The  effects  will  also  differ  if  the  lesion  affects 
both  lateral  halves  of  the  cord  or  only  one. 

Wherever  the  lesion  be  situated  within  the  cervical  enlarge- 
ment, the  arms  and  legs  will  gradually  become  paralyzed ;  the 
arms  and  hands  usually  becoming  first  numb  and  paretic,  and 
the  lower  limbs  exhibiting,  for  some  time,  only  a  sense  of 
weakness  and  evidences  of  an  increased  reflex  excitability.  A 
sense  of  constriction  around  the  chest  (the  so-called  ''cinc- 
ture feeling")  is  generally  present,  the  seat  of  which  varies 
with  that  of  the  exciting  lesion. 

When  the  lesion  is  situated  at  the  upper  part  of  the  en- 
largement, the  motor  and  sensory  symptoms  will  be  manifest- 
ed in  the  lower  extremities,  the  trunk,  and  in  nearly  all  the 

'  The  reader  is  referred  to  the  pages  on  the  third  cranial  and  pneumogastric  nerves 
for  details  as  to  the  effects  upon  the  eye  or  heart. 


630  THE  SPINAL   CORD. 

regions  of  the  upper  extremities.  The  constricting  band  around 
the  thorax  is  referred  to  the  level  of  the  clamcles^  and  dyspncBa 
is  often  excessive.  If  you  will  look  at  the  diagrammatic  cut/ 
you  will  perceive  that  the  brachial  plexus  is  marked  as  asso- 
ciated with  the  upper  part  of  the  cervical  enlargement,  and 
the  ulnar  nerve  with  the  lower  part ;  hence  the  paralysis  of 
the  arms  in  this  case  would  naturally  be  manifested  in  almost 
all  of  the  regions  of  the  upper  extremity,  and  also  in  those 
parts  supplied  by  the  brachial  plexus  above  the  clavicle. 

If  the  lesion  be  situated  in  the  lower  part  of  the  cervical 
enlargement,  the  symptoms  exhibited  will  include  a  loss  of 
faradic  reaction  of  those  muscles  which  are  supplied  by  the 
ulnar  nerve  (rather  than  those  of  the  arm  and  the  extensors 
of  the  forearm),  and  atrophy  of  these  muscles  will  often  be 
developed,  chiefly  in  the  flexors  of  the  wrist  and  the  small 
muscles  of  the  hand."  The  same  sense  of  constriction  (cinc- 
ture feeling),  as  experienced  in  most  spinal  lesions  of  a  local 
character,  will  exist,  but  it  will  be  referred  to  the  upper  part 
of  the  chest.  A  paralytic  condition  of  the  muscles  of  the 
trunk  (the  intercostals,  triangularis  stemi,  and  the  accessory 
muscles  of  respiration),  as  well  as  of  the  abdominal  muscles, 
will  be  detected  in  severe  cases,  rendering  both  inspiration 
and  expiration  embarrassed,  and  thus  adding  to  the  danger 
to  life.  The  lower  limbs  may  exhibit  evidences  of  numbness, 
anaesthesia,  paresis,  or  complete  paralysis,  depending  upon 
the  extent  of  the  lesion  and  the  destruction  done  to  the  tis- 
sues of  the  cord.  A  condition  of  paralysis  may  also  exist  in 
the  upper  extremity. 

In  surgical  injuries  to  the  upper  portion  of  the  cord,  a 
peculiarity  is  often  noticed  in  the  temperature  of  the  body, 
which  is  sometimes  greatly  elevated.  This  clinical  feature 
may  be  associated  with  a  marked  retardation  of  the  action  of 
the  heart  (apparently  confirming  the  situation  of  an  accelera- 
tory  center  for  that  organ  in  the  spinal  cord). 

'  See  page  626  of  this  volume. 

'  The  reader  is  referred  to  subsequent  pages  for  the  symptoms  of  ulnar  paralysis. 


FOCAL  LESIONS  IN  THE  DORSAL  REGION.  631 

FOCAL    LESIOi^S    OF  THE    MID-DORSAL    REGIOI^   OF  THE   SPINAL   CORD. 

In  the  early  stages  of  this  condition  the  lower  limbs  be- 
come paretic,  and  a  condition  of  increased  reflex  excitability 
is  manifested  by  a  rigidity  and  stiffness  of  the  impaired  mus- 
cles whenever  the  patient  attempts  to  stand  or  walk.  As  the 
disease  progresses,  the  muscles  become  paralyzed  and  contrac- 
tured  *  (probably  on  account  of  changes  of  a  secondary  char- 
acter in  the  lateral  columns  of  the  cord).  In  some  cases,  the 
reflex  movements  assume  the  type  of  spasms,  so  as  to  exhibit 
both  tonic  and  clonic  contractions.  It  was  this  symptom 
which  suggested  to  Brown-Sequard  the  name  of  "  spinal  epi- 
lepsy," since  it  occurs  when  the  patient  is  exposed  to  the 
slightest  peripheral  irritation,  and  often  when  in  the  recum- 
bent posture."  The  sense  of  constriction  around  the  body  is 
referred  to  the  region  of  the  navel,  or  that  of  the  lower  ribs, 
or  possibly  as  high  as  the  axilla,  since  it  may  be  taken  as  a 
relative  guide  to  the  highest  limit  of  the  lesion.  A  peculiarity 
exists  in  this  condition  as  regards  the  bladder  and  the  rec- 
tum ;  although  they  may  be  paralyzed,  they  are  often  enabled 
by  the  aid  of  reflex  action  to  expel  their  contents,  thus  appar- 
ently having  regained  their  function.  In  the  early  stages,  the 
urine  and  faeces  may  be  too  hastily  expelled  for  the  comfort 
of  the  patient,  often  compelling  the  performance  of  either  act 
before  a  proper  place  can  be  reached ;  but,  in  the  advanced 
stages,  the  urine  is  retained  to  such  an  extent  as  to  cause  an 
'^overflow,"  which  is  often  mistaken  for  an  actual  inconti- 
nence," since  a  constant  dribbling  is  present.  This  symptom 
is  always  an  indication  for  the  regular  use  of  a  catheter.  The 
sexual  function  seems  to  be  often  unimpaired,  as  coition  is 
frequently  possible.  It  is  seldom  that  the  paralyzed  muscles 
exhibit  a  tendency  to  atrophy,  and  the  electrical  reaction  of 

^  A  term  used  in  contradistinction  to  the  word  "  contracted,"  to  designate  a  perma- 
nent shortening  rather  than  a  temporary  response  to  a  motor  impulse. 

2  The  presence  of  urine  in  the  bladder  or  of  faeces  in  the  rectum  may  often  create 
these  spasms. 

3  For  the  diagnosis  between  these  two  conditions,  the  reader  is  referred  to  "  A  Prac- 
tical Treatise  on  Surgical  Diagnosis,"  by  the  author.  WiUiam  Wood  &  Co.,  New  York, 
1880. 


632  THE  SPINAL   CORD. 

the  affected  parts  is  either  normal  or  exaggerated.  The  chief 
seat  of  weakness  is  usually  detected  first  in  the  feet,  and  the 
paralysis  gradually  involves  the  entire  lower  limbs. 

FOCAL  LESIONS  ABOVE  THE  LUMBAR    ENLARGEMENT   OF    THE   SPINAL 

CORD. 

In  this  situation,  a  focal  lesion  of  the  cord  produces  about 
the  same  sensory  and  motor  symptoms  as  those  described  in 
connection  with  a  lesion  of  the  mid-dorsal  region,  with  the 
exception  that  the  reflex  spasms^  present  in  the  paralyzed 
muscles,  are  perhaps  somewhat  less  violent  than  when  the 
lesion  is  higher  up  the  cord.  These  tonic  and  clonic  spasms 
are,  however,  sufficiently  well  marked  to  constitute  a  promi- 
nent symptom,'  and  they  indicate  an  increased  reflex  excita- 
bility of  the  gray  matter  of  the  cord  below  the  seat  of  the 
lesion.  An  ingenious  explanation  of  this  increased  reflex  has 
been  advanced  by  Professor  Seguin  of  this  city,  which  seems 
to  merit  respectful  consideration.  I  quote  from  a  late  paper* 
of  his  upon  affections  of  the  spinal  cord,  as  follows : 

''The  classic  theory  of  the  physiology  of  contracture  in 
hemiplegia  is  that  it  is  due  to  the  secondary  degeneration — 
^.  e.,  actively  caused  by  the  lesion  of*  the  posterolateral  col- 
umn. Seven  years  ago  (see  "  Archives  of  Scientific  and  Prac- 
tical Medicine,"  vol.  i,  p.  106, 1873)  I  rejected  this  hypothesis, 
and  suggested  a  different  one,  which  I  have  since  elaborated 
and  taught  in  my  clinical  lectures  at  the  College  of  Physicians 
and  Surgeons,  New  York.  This  hypothesis,  which  I  intend 
shortly  to  publish  in  detail,  is  briefly  that  the  spasm  is  due, 
not  to  direct  irritation  from  the  sclerosed  (?)  tissue  in  the 
postero-lateral  column,  but  to  the  cutting  off  of  the  cerebral 
influence  by  the  primary  lesion,  and  the  consequent  prepon- 
derance of  the  proper  or  automatic  spinal  action — an  action 
which  is  mainly  reflex.  This  theory  explains  the  phenomena 
observed  in  cases  of  primary  spinal  diseases  with  descending 
degeneration,  and  can  be  reconciled  with  results  of  experi- 

*  These  reflex  spasms  have  been  called  by  Brown-S6quard  "  spinal  epilepsy." 
'  "  Annals  of  Anatomical  and  Surgical  Society,"  Brooklyn,  December,  1880. 


FOCAL  LESIONS  OF  TEE  LUMBAR  REGION.  633 

ments  on  animals  (increased  reflex  power  of  spinal  cord  after 
a  section  high  up,  Brown- Sequard  ;  inhibitory  power  of  the 
encephalon  on  the  spinal  cord,  Setchenow)." 

The  urinary  and  rectal  organs  are  affected  in  about  the 
same  way  as  in  lesions  of  the  dorsal  region.  Coition  is  often 
possible,  and  erections  are  normally  frequent.  The  rectum  is 
paralyzed,  as  a  rule,  and  constipation  is  usually  present  on 
that  account.  Micturition  becomes  slow  and  interrupted,  as 
the  bladder  grows  paretic,  and  retention  and  overflow  are 
produced  later  on  in  the  disease. 

The  paralysis  of  the  extremities  is  first  noticed  in  the  feet, 
which  have  long  before  exhibited  a  sense  of  weakness  and  easy 
fatigue.  Numbness  and  anaesthesia  usually  accompany  the 
motor  paralysis,  and  extend  as  high  as  the  groin  or  the  waist. 
The  sense  of  a  constricting  band  around  the  body  is  present 
here,  as  in  lesions  of  other  localities,  and  is  referred  to  the  waist, 
below  the  level  of  the  umbilicus,  or  at  the  level  of  the  hips. 

FOCAL  LESION^S  OF  THE   LUMBAR  EN^LARGEMENT. 

If  you  will  look  at  the  diagram  of  the  spinal  cord  upon 
the  blackboard, '  you  will  perceive  that  the  lower  portion  of 
the  lumbar  enlargement  is  represented  as  giving  origin  to  the 
sciatic  nerve ;  hence,  it  is  reasonable  to  expect  that  a  lesion 
situated  in  the  lower  part  of  this  enlargement  would  be  mani- 
fested by  symptoms  of  an  incomplete  paraplegia,  in  which 
the  muscles  supplied  by  the  sciatic  nerves  would  be  the  most 
affected.''  Now,  this  fact  seems  to  be  confirmed  by  clinical 
experience,  since  the  feet,  legs,  posterior  aspect  of  the  thighs, 
and  the  region  of  the  nates  are  chiefly  paralyzed  when  the  le- 
sion is  so  situated.  The  bladder  is  unaffected,  but  the  sphinc- 
ter ani  muscle  is  often  rendered  paretic,  or  it  may  be  entirely 
paralyzed.  The  portions  of  the  limbs  which  are  to  become  the 
seat  of  paralysis  usually  exhibit  a  sense  of  numbness  before 
the  effects  of  the  lesion  are  fully  developed,  and,  in  case  the 

^  The  reader  is  referred  to  the  figure  on  page  626  of  this  volume. 
^  The  reader  is  referred  to  the  pages  which  treat  of  the  clinical  points  pertaining  to 
the  sciatic  nerve,  for  the  symptoms  of  this  type  of  paralysis. 


634 

posterior  columns  of  the  cord  be  involved,  complete  anaesthe- 
sia may  also  exist  in  the  parts  supplied  with  motor  power  by 
the  sciatic  nerve.  The  condition  of  the  paralyzed  muscles, 
as  to  their  electrical  reactions,  and  the  presence  or  absence  of 
the  evidences  of  increased  reflex  excitability  will  depend 
greatly  upon  how  much  damage  has  been  done  to  the  gray 
matter  of  the  lumbar  enlargement.  If  the  gray  matter  be  so 
destroyed  as  to  impair  its  function,  the  reflex  movements  will 
be  absent ;  and,  if  the  trophic  function  of  the  cord  be  affected 
by  changes  in  the  ganglion  cells  of  the  gray  matter,  the  para- 
lyzed muscles  will  undergo  atrophy.  The  sense  of  constric- 
tion, or  "band  feeling,"  will  usually  be  referred,  in  this  le- 
sion, either  to  the  ankle,  leg,  or  thigh. 

FOCAL    LESIONS    CONFIKED    TO    THE    LATEKAL    HALF  OF  THE  SPINAL 

COED. 

In  discussing  the  focal  lesions  of  the  cord,  we  have  de- 
scribed the  clinical  points  which  are  afforded  by  destruction, 
to  a  greater  or  less  extent,  of  the  substance  of  the  cord  in  both 
of  its  lateral  halves  ;  hence,  the  motor  and  sensory  symptoms 
have  been  usually  referred  to  both  sides  of  the  body.  It  was 
necessary  to  thus  describe  them,  since  focal  lesions,  unless 
traumatic,  are  seldom  confined  to  one  lateral  half  of  the 
cord  ;  but,  in  some  cases  which  may  be  presented  to  your 
notice,  where  a  tumor,  a  fractured  vertebra,  a  haemorrhage, 
a  severe  contusion,  or  some  other  localized  lesion  exists,  the 
injury  done  to  the  spinal  cord  may  be  confined  exclusively 
to  one  lateral  half,  resulting  in  one  of  two  named  conditions, 
viz.,  "spinal  hemiplegia"  and  "hemi-paraplegia."  Before 
proceeding  to  the  special  consideration  of  either  of  these 
conditions,  it  may  prove  of  advantage  to  review  some  few 
points  in  the  physiology  of  the  cord,  and  to  again  direct  your 
attention  to  the  two  plates  upon  the  blackboard,  which  are 
already  familiar  to  you. 

This  plate '  shows  you  that  any  lesion  of  a  lateral  half  of 
the  spinal  cord  must  produce  anaesthesia  in  the  opposite  side 
of  the  hody^  since  all  the  sensory  nerves  decussate  and  enter 

'  See  Fig.  179  of  this  volume. 


FOCAL  LESION   OF  A  LATERAL  HALF  OF  THE  CORD.   635 


M  S 

i  I 


M.' 


/•'' 


Fig 


> 


li 


SM 
II 


-t 


!/ 


the  gray  matter  of  the  cord,  which  serves  as  a  conducting 
medium  for  sensory  impressions,  while  the  motor  symptoms 
produced  by  the  same  lesion  must  be  confined  to  the  same 
side  of  the  body  as  the  lesion,  since  no  decussation  probably 
occurs  in  the  spinal  cord  (these  fibers  decussating  only  in  the 
medulla  oblongata). 

This  second  diagram'  will  further 
assist  you  to  appreciate  the  fact  that 
lateral  lesions,  as  well  as  those  which 
affect  the  entire  cord,  are  modified,  as 
regards  their  symptomatology,  by  the 
height  of  the  lesion  in  the  cord  ;  since 
the  motor  nerves,  and  the  special  cen- 
ters which  are  situated  in  the  cord  itself, 
will  only  be  affected  when  they  lie  below 
the  seat  of  the  lesion  or  are  directly  in- 
volved in  the  destructive  process.  It 
will,  therefore,  be  unnecessary  to  enter 
again  into  detail  as  to  the  full  bearings 
of  the  plate,  since  they  are  probably 
fresh  in  your  memory. 

When  the  focal  lesion  is  placed  high 
up  in  the  substance  of  the  spinal  cord,  the 
motor  paralysis  affects  one  side  only  of 
the  body  (provided  the  lesion  is  confined  to  a  lateral  half),  and 
the  term  "spinal  hemiplegia "  is  applied  to  this  form  of  paral- 
ysis in  contradistinction  to  a  hemiplegia  of  cerebral  origin.  If 
the  spinal  lesion  be  situated  in  the  dorsal  region  and  be  con- 
fined to  the  lateral  half  of  the  cord,  a  motor  paralysis  of  one 
half  of  the  same  side  of  the  body  below  the  seat  of  the  lesion 
is  developed,  a  condition  to  which  the  term  ''hemi-paraple- 
gia"is  commonly  applied.  Inclosing  the  clinical  aspects  of 
lesions  of  the  spinal  cord,  it  will  be  necessary,  therefore,  for 
us  to  consider  the  essential  features  of  these  two  remaining 
conditions. 


186.—^ 


diagram    to 


show  the  course  of  the 
motor  and  sensory  patlis 
in  the  spinal  cord. 
(Brown-Sequard.) 

D,  decussation  of  pyramids ; 
M,  motor  paths ;  S,  sen- 
sory paths. 


'  The  reader  is  referred  to  Fig.  179  of  this  volume  for  details  as  to  the  utility  of  this 
figure  in  the  study  of  spinal  affections. 


636 


THE  SPINAL   CORD. 


SPINAL  HEMIPLEGIA. 

In  order  to  produce  a  typical  case  of  this  condition,  it  is 
necessary  to  have  a  lateral  focal  lesion  of  the  cord  in  its  upper- 
most part  (in  or  above  the  cervical  enlargement  of  the  cord).  If 
we  suppose,  then,  that  such  a  lesion  be  present,  let  us  see  what 
we  might  reasonably  expect,  on  purely  physiological  grounds, 
would  be  the  result.    We  can  then  examine  the  clinical  rec- 

Medulla. 

V'y.il      I Ilypo-glossal  N. 


Axis,  < 

dC.  V.  <; 

I    \  6th  C.  V.  <' 

"I    )  7th  C.V.  <( 

ID.  V.  <^ 


11th  D.  V.  <[ 
12th  D.  V.  <^ 

1  L.  V.  <^ 

2  L.  V.  <; 


Pneumogastric  N. 
Phrenic  N. 

Brachial  plexus. 
Ulnar  nerve. 


Crural  N. 


Sciatic  N. 


Fra.  187. — A  diagram  to  show  the  relation  of  the  spinous  processes  of  th£  vertebra  to  spi- 
tial  nerves.     (Malgaigne  '  and  Seguin.) 

ords  of  such  cases,  and  either  confirm  our  deductions  or  gain 
some  additional  information.  Such  a  lesion  would,  in  the  first 
place,  shut  off  all  motor  impulses  sent  out  from  the  brain  to 
parts  below  the  lesion,  on  the  same  side  as  the  lesion,  since 

^  "  Trait6  d'Anatomie  Chirurgicale." 


SPINAL  HEMIPLEGIA.  637 

the  decussation  of  the  motor  fibers  has  already  taken  place  in 
the  medulla  ;  hence  motor  paralysis  should,  theoretically,  oc- 
cur in  the  arm  and  leg  of  the  side  of  the  body  corresponding 
to  the  seat  of  the  exciting  lesion,  and  the  trunk  should  also  be 
paralyzed  upon  that  side.  This  we  find,  clinically,  to  be  true,' 
with  the  exception  that  the  intercostal  nerves  often  retain 
their  motor  power  when  the  nerves  of  the  arm  and  leg  are  no 
longer  capable  of  carrying  motor  impulses.  In  the  second 
place,  we  should  expect  to  find  that  the  sensation  of  the  side 
of  the  body  opposite  to  the  seat  of  the  lesion  would  be  de- 
stroyed or  greatly  impaired,  since  the  sensory  nerves  decus- 
sate throughout  the  entire  length  of  the  cord.  This  we  also  find 
confirmed  by  clinical  facts  ;  and  so  perfect  is  this  ansesthesia 
that  the  line  can  often  be  traced  to  the  mesial  line  of  the  body 
exactly,  and  upward  to  the  limit  of  the  exciting  lesion.  In 
the  third  place,  the  situation  of  the  cilio-spinal  center  in  the 
cervical  region  of  the  cord  would  naturally  suggest  some  effects 
upon  the  pupil,''  and  the  circulation  and  temperature  of  the 
face,  neck,  and  ear  of  the  same  side.  This  is  also  confirmed,  as 
the  pupil  does  not  respond  to  light,  but  it  still  acts  in  the  ac- 
commodation of  vision  for  near  objects,  and  the  skin  of  the 
regions  named  becomes  red  and  raised  in  temperature.  Fi- 
nally, the  presence  of  i^aso-motor  centers  in  the  cord  might 
occasion  a  rise  in  temperature  in  the  paralyzed  muscles  ;  and, 
strangely  confirmatory  of  this  fact,  we  often  find  the  tempera- 
ture of  the  paralyzed  side  of  the  body  hotter  than  that  of  the 
ansesthetic  side. 

In  some  exceptional  cases,  the  face,  arm,  and  trunk  are 
alone  paralyzed,  the  legs  seeming  to  escape,  and  often  giving 
evidence  of  reflex  spasm  (perhaps  most  commonly  on  the 
anaesthetic  side).  This  must  be  explained  as  the  result  of 
incomplete  destruction  of  the  lateral  half  of  the  cord. 

^ThG  researches  of  Brown-Sequard,  as  early  as  1849,  and  his  published  memoirs 
(1863-'5  and  1868,  1869),  have  probably  done  more  to  clear  up  this  field  and  to  place  it 
upon  a  positive  foundation  than  those  of  any  other  observer. 

*  The  reader  is  referred  to  pages  360  and  381  of  this  volume. 


43 


638  THE  SPINAL   CORD. 

HEMI-PARAPLEGIA.  ' 

This  condition  is  the  result  of  some  focal  lesion  of  the 
spinal  cord  in  the  dorsal  region^  which- involves  only  its  lateral 
half.     The  results  of  such  a  lesion  differ  but  little  from  those    I 
of  one  causing  spinal  hemiplegia,  as  regards  the  motor  and    I 
sensory  symptoms,  excepting  that  the  situation  of  the  excit-    < 
ing  cause  is  below  the  cervical  enlargement,  where  the  nerves    I 
to  the  upper  extremity  are  given  off,  and  where  the  cilio-    j 
spinal  center  is  situated.     For  that  reason  the  muscles  of  the    \ 
upper  extremity  are  not  paralyzed,  nor  are  the  effects  upon    I 
the  pupil  and  the  skin  of  the  face,  ear,  and  neck  (mentioned    , 
as  present  in  spinal  hemiplegia)  produced.     The  muscles  be-    | 
low  the  seat  of  the  lesion  are  paralyzed  on  the  side  of  the  body    j 
corresponding  to  the  exciting  cause,  and  the  skin  is  sometimes    j 
rendered  hypersesthesic  upon  that  side ; '  while  the  integu-    , 
ment  of  the  side  opposite  to  the  lesion  is  deprived  of  sensi- 
bility.    The  bladder  and  rectum  may  be  paralyzed  in  some   ^ 
instances.     The  sense  of  constriction,  or  *'band  feeling,"  will 
vary  with  the  seat  of  disease  in  the  spinal  cord.     The  amount    : 
of  reflex  irritability  and  the  presence  or  absence  of  muscular    \ 
atrojphy  in  the  parts  paralyzed  will  depend  upon  the  depth    ^ 
of  the  lesion  in  the  spinal  cord  and  the  changes  which  have    j 
been  produced  in  the  gray  matter.     The  same  increase  of  tem- 
perature in  the  paralyzed  limb,  which  was  mentioned  as  oc-   j 
curring  in  spinal  hemiplegia,  may  also  be  present  in  this  vari-   \ 
ety  of  paralysis.  j 

Should  the  side  affected  with  anaesthesia  give  any  evidence  \ 
of  motor  paralysis  or  muscular  weakness,  or  symptoms  of  | 
anaesthesia  appear  upon  the  side  where  the  motor  paralysis  j 
is  present,  you  may  regard  either  one  as  conclusive  evidence  ■ 
that  the  exciting  lesion  is  progressing,  and  that  the  opposite  '; 
lateral  half  of  the  cord  is  being  involved  to  a  greater  or  less  \ 
extent.  i 


*  This  is  probably  due  to  some  irritation  of  the  gray  matter  of  the  cord. 


J 


THE  SPIN^AL  I^ERYES. 

THEIR    ORIGIN,   DISTRIBUTION,   FUNCTIONS,  AND 
CLINICAL  IMPORTANCE. 


n 


THE   SPIIJAL  IsTEEYES, 


We  have  now  considered  the  general  points  in  the  con- 
struction of  the  cerebro-spinal  axis,  and  the  clinical  facts 
which  pertain  to  the  brain  and  spinal  cord.  We  have  also 
separately  discussed  those  nerves  which  are  connected  with 
the  brain,  and  have  noted  all  the  peculiarities  in  their  distri- 
bution and  anastomoses,  which  seem  to  shed  a  light  upon 
their  physiological  action  or  the  clinical  features  which  each 
of  them  presents.  It  now  remains  for  us  to  investigate  those 
nerves  of  the  neck,  trunk,  and  the  extremities  which  are  con- 
nected with  the  spinal  cord,  and  are  called  '^  spinal  nerves," 
in  contradistinction  from  the  nerves  of  cranial  origin,  or 
those  of  the  sympathetic. 

The  spinal  nerves  comprise  thirty-one  pairs,  which  escape 
from  each  side  of  the  spinal  cord  by  two  roots,  called  the 
anterior  or  ''motor  root,"  and  the  posterior  or  "sensory 
root."  These  two  roots  join  with  each  other,  in  every  in- 
stance, to  form  one  nerve,  which  is  named  in  accordance  with 
its  situation  and  the  region  of  the  vertebral  column  from 
which  it  escapes ;  since  the  nerves,  so  formed,  pass  through 
foramina  between  the  pedicles  of  the  vertebrae,  throughout 
the  entire  length  of  the  spinal  column.  Thus  we  have  eight 
pairs  of  cermcal  nerms,  escaping  upon  either  side  of  the 
cervical  vertebrae  ;  twelve  pairs  of  dorsal  nerves^  bearing  the 
same  relation  to  the  dorsal  region  of  the  spine  ;  Jive  pairs  of 
lumbar  nerves  on  each  side ;  five  pairs  of  sacral  nerves^ 


642 


THE  SPmAL  NERVES. 


escaping  from  the  foramina  of  that  bone ;  and  one  pair  of 
coccygeal  nerves. 

As  mentioned  in  the  lectures  npon  the  construction  of  the 
spinal  cord,  the  anterior  roots  of  the  spinal  nerves  are  con- 
nected with  the  gray  matter  of  the  anterior  horns  ;  while  the 
posterior  roots  are  connected  with  the  posterior  horns  of  the 


Fio.  \%^.— Cervical   por-  FiG.    l^^d.— Dorsal-  por-         FiG.   1^0.— Inferior  por- 

tion of  the  spinal  cord.  Hon  of  the  spinal  cord.  tion  of  the  spinal   cord, 

(Hirschfeld.)  (Hirschfeld.)  and      cauda       equina. 

(Hirschfeld.) 
1,  antero-inferior  wall  of  the  fourth  ventricle ;  2,  superior  peduncle  of  the  cerebellum  ; 
3,  middle  peduncle  of  the  cerebellum ;  4,  inferior  peduncle  of  the  cerebellum  ;  5,  in- 
ferior portion  of  the  posterior  median  columns  of  the  cord ;  6,  glosso-pharyngeal 
nerve ;  7,  pneumogastric  ;  8,  spinal  accessory  nerve  ;  9,  9,  9,  9,  dcntated  ligament ; 
10, 10,  10,  10,  posterior  roots  of  the  spinal  nerves  ;  11,  11,  11,  11,  posterior  lateral 
groove;  12,  12,  12,  11,  ganglia  of  the  posterior  roots  of  the  nerves  ;  13,  IZ^antei-ior 
roots  of  the  nerves  ;  14,  division  of  the  nerves  into  two  branches  ;  15,  lower  extremity 
of  the  cord  ;  16,  16,  coccygeal  ligament ;  17,  17,  cauda  equina  ;  I — YUl,  cei-vical  nerves  ; 
I,  II,  III,  IV — XII,  dorsal  nerves  ;  I,  II — V,  lumbar  nerves  ;  I — V,  sacral  nei'ves. 

gray  matter.     Like  all  sensory  neves,  the  posterior  roots  have 
a  ganglionic  enlargement"^  developed  upon  them,  while  the 

'  The  presence  of  a  ganglion  upon  a  cerebro-spinal  nerve  is  always  an  evidence  of  its 
sensory  character. 


THE  MOTOR  AND  SENSORY  ROOTS.  643 

anterior  roots,  being  motor  in  function,  do  not.  The  roots  of 
the  first  cervical  nerves  are  small,  short,  directed  horizontally, 
and  the  anterior  is  the  larger  of  the  two  ;  those  of  the  remain- 
ing cervical  nerves  become  larger,  longer,  and  more  oblique 
as  you  descend  the  cord,  and  the  posterior  root  is  consider- 
ably larger  than  the  anterior.  In  the  dorsal  region,  the  first 
dorsal  nerve  resembles  the  lower  cervical  nerves  as  to  the 
actual  and  relative  size  of  its  roots,  but  the  roots  of  the  re- 
maining dorsal  nerves  are  smaller  than  those  of  the  cervical 
region,  and  more  nearly  equal  in  their  relative  size.  The 
roots  of  the  lumbar  and  upper  sacral  nerves  again  increase 
in  size  from  above  downward.  Finally,  the  lower  sacral  and 
the  coccygeal  nerves  show  a  gradual  decrease  in  the  size  of 
their  roots,  the  last  sacral  and  the  coccygeal  nerves  having 
the  smallest  roots  of  any  of  the  spinal  nerves.  As  regards 
the  relative  size  of  the  anterior  and  posterior  roots,  the  lum- 
bar, sacral,  and  coccygeal  nerves  exhibit  but  little  difference. 

The  length  and  inclination  of  the  roots  of  the  spinal  nerves 
increase  from  the  first  to  the  last ;  hence  the  place  of  escape 
of  a  spinal  nerve  does  not  indicate  its  seat  of  origin.  As  the 
spinal  cord  does  not  descend  beyond  the  first  lumbar  verte- 
bra, the  length  of  the  roots  of  the  lumbar,  sacral,  and  coccy- 
geal nerves  increases,  from  nerve  to  nerve,  by  the  thickness 
of  one  vertebra. 

The  trunk  of  each  spinal  nerve,  after  its  escape  from  the 
vertebral  canal,  immediately  divides  into  an  anterior  and  a 
posterior  primary  division. 

In  treating  of  the  spinal  nerves,  I  will  first  direct  your 
attention  to  the  four  upper  cervical  nerves,  since  they  enter 
into  the  formation  of  the  cervical  plexus  ;  then  to  the  remain- 
ing cervical  and  the  first  dorsal  nerves,  since  they  enter  into 
the  formation  of  the  brachial  plexus  ;  and,  later  on,  the 
dorsal,  lumbar,  sacral,  and  coccygeal  nerves  will  be  separately 
considered.  By  this  method  of  subdivision,  which  is  the  one 
usually  followed  by  all  authors  upon  anatomy,  the  nerves  can 
be  more  satisfactorily  traced  from  their  origin  to  their  termi- 
nal distribution  than  if  each  nerve  were  treated  of  separately, 


644  THE  SPINAL  NERVES. 

since  some  enter  into  the  formation  of  plexuses,  and  thus  lose 
their  individuality. 

The  axioms  regarding  the  distribution  of  nerves  to  the 
muscles,  joints,  and  skin,  which  I  quoted  in  the  first  lecture 
of  this  winter's  course,  will  be  so  constantly  of  use  in  the 
study  of  the  spinal  nerves  that  they  will  again  bear  repetition. 
The  substance  of  my  remarks  in  that  lecture  was  about  as 
follows : 

It  is  claimed  by  John  Hilton '  that,  if  we  trace  the  distri- 
bution of  the  nerve  filaments  from  any  special  nerve  trunk  to 
the  muscles,  we  shall  find  that  only  those  muscles  are  supplied 
by  each  of  the  individual  nerves  which  are  required  to  render 
complete  the  performance  of  the  functions  for  which  that 
nerve  was  designed  ;  and  that,  if  muscles  were  classified  on  a 
basis  of  their  nerve  supply,  instead  of  in  groups  of  mere  rela- 
tionship as  to  locality,  a  self-evident  physiological  relation 
would  be  shown  which  would  tend  greatly  to  simplify  a 
knowledge  of  the  muscular  system  in  its  practical  bearings, 
and  to  prove  a  design  on  the  part  of  the  Creator. 

Thus,  he  says,  we  frequently  find  muscles  close  together 
and  still  supplied  by  separate  nerves,  one  of  which  has  possi- 
bly to  go  a  long  way  out  of  a  direct  course  to  reach  it,  which 
is  contrary  to  the  usual  method  of  Nature,  who  always  uses 
the  simplest  means  to  accomplish  her  designs ;  but,  if  we  ex- 
amine the  action  of  these  two  muscles,  we  will  find  that  each 
one  acts  in  unison  with  the  other  muscles  supplied  by  the 
.same  nerve,  and  that,  to  produce  this  perfect  accord,  Nature 
takes  what,  to  a  hasty  glance,  would  seem  to  be  a  needless 
step. 

He  also  lays  down  certain  axioms,  pertaining  to  the  dis- 
tribution of  nerves  and  the  diagnostic  value  of  pain,  which 
have  been  often  repeated  in  these  lectures,  and  can  not  but  be 
most  profitable  to  those  who  use  them  as  a  guide.  They  are 
as  follows : 

''Superficial  pains  on  both  sides  of  the  body,  which  are 
symmetrical^  imply  an  origin  or  cause^  the  seat  of  which  is 

»  "  Best  and  Pain,"  London,  1876  (New  York,  1879). 


THE  AXIOMS   OF  NERVE  BISTEIBUTIOK  645 

central  or  hilateral ;  while  unilateral  pain  implies  a  seat  of 
origin^  which  is  one-sided^  and^  as  a  rule^  exists  on  the  same 
side  of  the  body  as  the  pain^ 

The  bearings  of  tliis  first  axiom  will  be  rendered  very  ap- 
parent when  the  regions  of  the  neck  and  trunk  are  considered, 
since  the  symptom  of  local  pain  is  of  the  greatest  value  in 
connection  with  diseases  affecting  the  bones  of  the  spinal  col- 
umn and  the  spinal  cord  which  they  invest ;  but  that  the 
same  rule  may  be  applied  to  any  of  the  cranial  nerves,  with  a 
degree  of  certainty  which  seldom  admits  of  error,  has  been 
shown  in  cases  quoted  in  connection  with  the  motor  oculi, 
trigeminus,  facial,  and  other  nerves. 

The  second  axiom  is  as  follows : 

"  The  same  trunks  of  nerr)es^  whose  branches  supply  the 
groups  of  muscles  moving  a  joints  furnish  also  a  distribu- 
tion of  nerves  to  the  shin  over  the  insertions  of  the  same  mus- 
cles ;  and  the  interior  of  the  joint  moved  by  these  muscles 
receives  a  nerve  supply  from  the  same  source.'''' 

By  this  axiom,  a  physiological  harmony  is  shown  between 
these  various  cooperating  structures.  Thus,  any  joint,  when 
inflamed,  may,  by  a  reflex  act  through  motor  branches  from 
the  same  trunk  by  which  it  is  itself  supplied,  control  the  mus- 
cles which  move  it,  and  thus  insure  the  rest  and  quiet  neces- 
sary to  its  own  repair. 

Spots  of  local  tenderness  in  the  cutaneous  surface  may, 
for  this  reason,  likewise  be  often  considered  as  a  guide  to  a 
source  of  irritation  of  some  of  the  structures  supplied  by  the 
same  nerve,  viz.,  the  muscles  underneath  it,  or  the  Joints 
which  are  moved  by  them  ;  and,  thus,  even  remote  affections 
can  be  accurately  determined,  which,  were  this  axiom  not 
used  as  a  guide,  might  escape  recognition  till  an  advanced 
stage  of  the  disease  had  been  reached. 

It  is  well,  however,  to  quote  one  other  axiom,  laid  down 
by  the  same  author,  before  leaving  the  subject  of  the  diag- 
nostic value  of  the  cutaneous  nerves  as  indicators  of  existing 
disease  of  other  organs,  viz.  : 

"  Every  fascia  of  the  body  has  a  muscle  or  muscles  at- 


646  THE  SPINAL  NERVES. 

tacJied  to  it ;  and  every  fascia  must  he  considered  as  one  of 
the  points  of  insertion  of  the  muscles  connected  to  it^^^  in  fol- 
lowing the  previous  axiom  as  to  the  cutaneous  distribution 
of  nerves. 

This  guide  is  especially  important  in  case  the  rule  be  ap- 
plied to  the  extremities  (arms  and  legs)  where  these  fasciae, 
extend  over  large  surfaces,  more  or  less  remote  from,  and  ap- 
parently unconnected  with,  the  muscles  attached  to  them  ;  but 
it  is  mentioned  in  this  connection  for  the  especial  object  of 
calling  the  attention  of  the  reader  to  those  general  rules  which 
govern  the  distribution  of  the  nerves  in  their  entirety,  before 
proceeding  to  apply  them  in  all  their  individual  bearings  : 

Without  this  nervous  association  between  the  muscular 
structures  and  those  composing  the  joints,  there  could  be  no 
intimation  given  by  the  internal  parts  of  their  exhaustion  or 
fatigue.  Again,  through  the  medium  of  this  same  association 
between  the  skin  and  the  muscles,  great  security  is  given  to 
the  joints,  by  the  muscles  being  made  aware  of  the  point  of 
contact  of  any  extraneous  force  or  violence.  Their  involun- 
tary contraction  instinctively  makes  the  tissues  surrounding 
the  joints  tense  and  rigid,  and  this  brings  about  an  improved 
defense  for  the  subjacent  joint  structures. 

From  the  conclusion  of  his  great  work,  in  which  Hilton  en- 
deavors to  prove  that  mechanical  rest  may  be  used  as  a  cure 
for  most  of  the  surgical  disorders,  the  following  sentences  are 
quoted,  since  they  can  not  be  too  often  repeated  : 

*'I  have  endeavored  to  impress  upon  you  the  fact  that 
every  pain  has  its  distinct  and  pregnant  signification  if  we 
will  hut  carefully  search  for  it. 

"In  the  pain  which  follows  the  intrusion  of  a  particle  of 
dust  on  to  the  conjunctiva,  and  the  closure  of  the  eyelid  for 
the  security  of  rest,  up  to  the  most  formidable  diseases  which 
we  have  to  treat — pain  the  monitor,  and  rest  the  cure — are 
starting  points  for  contemplation,  which  should  ever  be  pres- 
ent to  the  mind  of  the  surgeon." 

Now,  if  you  will  thoroughly  grasp  these  axioms,  not  only 
as  mere  words,  but  as  grand  principles^  which  can  be  used 


PROPER   USE  OF  TABLES  OF  NERVES.  647 

by  you  in  your  every-day  experience  as  counselors  of  the 
sick,  you  will  be  better  able  to  appreciate  the  tables  of 
nerve  distribution  which  I  am  constantly  presenting  to  you 
upon  the  blackboard,  so  that  you  can  record  them  in  your 
note-books.  These  tables  enable  you,  at  a  glance,  to  see  to 
what  muscles  each  separate  nerve  sends  filaments  of  distribu- 
tion, and  thus  innumerable  problems  are  being  constantly 
suggested  to  you  of  this  character  :  Why  does  this  nerve  sup- 
ply the  muscles  mentioned  and  omit  those  in  the  immediate 
vicinity  ?  What  is  the  common  physiological  function  which 
these  muscles  are  destined  to  perform  ?  How  may  this  nerve 
be  classed  from  its  physiological  action  ? 

It  is  only  by  such  a  system  of  self -inquiry  and  self-examina- 
tion that  you  are  enabled  to  become  the  master  of  the  science. 
The  nerves  are  then  no  longer  mere  cords,  running  without  a 
plan,  and  serving  only  as  a  tax  upon  the  memory,  but  electric 
wires,  placed  with  a  system  which  we,  as  yet,  can  not  begin 
to  understand  in  its  wonderful  adaptability  to  the  demands  of 
the  body,  but  which  a  little  study  will  show  is  remarkable  for 
its  simplicity  of  distribution,  if  we  but  seek  for  the  function 
of  each  nerve.  To  a  student  of  this  character,  the  nerves  be- 
come a  source  of  never-ending  delight,  since  they  serve  as  the 
key  to  many  problems  in  anatomy  which  had  previously  been 
involved  in  obscurity.  We  thus  learn  the  action  of  the  mus- 
cles^ since  the  nerves  which  supply  any  special  group  enable 
you  at  once  to  tell  that  those  have  a  similarity  of  function 
which  are  supplied  from  the  same  source,  while  those  sup- 
plied from  different  sources  are  not  only  dissimilar  in  their 
action,  but  have  some  bond  of  sympathy  with  other  muscles 
(possibly  far  distant)  which  are  similarly  supplied.  I  believe 
that  the  day  is  not  far  off  when  the  neri^ous  supply  will  consti- 
tute the  universally  recognized  basis  upon  which  muscles  will 
be  divided  into  groups  ;  and,  when  that  day  comes,  the  labor 
of  the  student  will  be  greatly  lessened,  and  his  grasp  of  the  sub- 
ject be  of  a  higher  and  more  comprehensive  order.  We  will  now 
pass  to  the  consideration  of  the  upper  four  cervical  nerves,  and 
the  cervical  plexus  which  is  formed  by  their  anterior  branches 


648 


THE   SPINAL  NERVES. 


THE  UPPER  CERVICAL  NERVES. 
A   CHART  OF  THE   NERVES   OF  THE   CERVICAL   REGION.  * 


First    Cervical 


{Svh-occipital). 


'  Posterior  division. 


^  Anterior  division. 


f  Brancli  to  posterior  division  of  second  cervical, 
Branches  to  the  posterior  a'anio-vertebral  set  of 

muscles, 
Branch  to  complexus  muscles, 
Branch  to  integument  of  occiput. 
'  Branch  to  rectus  cap.  ant.  major. 
Branch  to  rectus  cap.  ant.  minor. 
Branch  to  rectus  cap.  lateralis. 

r  Second  cervical, 
Communicating    J   Pneumogastiic, 
branches  to  1   Hypo-glossal, 

[  Superior  cervical  ganglion. 
Branch  to  occipito-atloid  articulation. 


Second  Cervical  - 
Nerve. 


Posterior    division 
(very    large     in 
size). 


f  Splenius, 
iCe 


External  branch  J  ^ervicalis  ascendens, 

y  Complexus. 
''Joins   with    first 


Internal  branch 
( Great  occipital 
nerve). 


Third   Cervical 
Nerve. 


cervical 
nerve, 
Supplies  integument  of  oc- 
ciput as  far  as  vertex. 
Gives  an  auricular  branch 
to  skin  of  ear. 
Filament  to  stemo-mastoid. 
Ascending  branch  (to  first  cervical  nerve), 
.  Anterior  division.  ■{  Descending  branch  (to  third  cervical  nerve). 
Filament  to  communicans  noni  nerve. 
Small  occipital  nerve  (occipitalis  minor), 
f  Splenius, 
Cervicalis  ascendens, 
Transversalis  colli, 
Trachelo-mastoid. 


r  Posterior  division. 


.  Anterior  division. 


External   branch 
(supplying) 


Internal    branch 
(supplying) 


Ascending 

branches. 


Descending 

branches. 


Fourth    Cervi- 
cal Nerve. 


Integument  of  occiput. 

Auricularis  magnus, 
Superficial  cervical^ 
Branch  to  second  cervical 

nerve, 
Branch  to  the  spinal  acces- 
sory, 
f  Filament  to  fourth  nerve, 
I  Filament  to  levator  anguli 
I      scapulae, 
■{  Supra-clavicular, 

Filament  to  communicans 
I      noni  nerve, 
(^  Filament  to  phrenic  nerve. 
Posterior  division  (distributed  to  muscles  of  the  back). 
Filament  to  third  cervical  nerve, 
Filament  to  fifth  cervical  nerve, 
Filament  to  phrenic  nerve, 
Filament  to  scalenus  medius, 
Filaments  to  supra-clavicular  nerve. 


Anterior  division. 


'  Modified  from  a  table  in  the  "  Essentials  of  Anatomy  "  (Dariing  and  Ranney).     New 
York,  Putnam's  Sons,  1880. 


J 


THE  UPPER   CERVICAL  NERVES. 


649 


If  you  will  look  at  the  table,  which  I  have  had  copied  for 
your  inspection, '  you  will  perceive  that  each  of  the  upper  four 
cervical  nerves  gives  off  an  anterior  and  posterior  branch,  im- 
mediately after  their  escape  from  the  vertebral  canal,  and  that 
the  distribution  of  each  of  these  branches  is  shown  in  detail. 
You  will  perceive  that  every  branch  which  supplies  the  in- 


FiG.  191. — Posterior  branch  of  tJie  second  cervical  nerve.     (Arnold.) 

1,  trunk  of  the  facial ;  2,  its  superior  branch,  or  temporo-facial ;  3,  the  inferior  branch, 
or  cervico-facial ;  4,  its  posterior  auricular  branch ;  5,  auriculo-temporal ;  6,  auri- 
cularis  raagnus  from  the  cervical  plexus ;  7,  its  mastoid  branch ;  8,  supra-acromial 
branch;  9,  supra-clavicular  branch;  10,  accessory  occipitalis  minor;  M^  occipitalis 
major;  12,  frontal  division  of  the  ophthalmic  nerve;  13,  infra-orbital  branch  of 
the  superior  maxillary ;  14,  mental  branches  of  the  inferior  dental  nerve ;  A,  pla- 
tysma  myoides ;  B,  sterno-mastoid ;  C,  trapezius. 

tegument  alone  is  underscored,'  while  the  muscular  branches 
are  not.  Thus,  the  great  occipital,  small  occipital,  great  au- 
ricular, superficial  cervical,  and  supra-clavicular  nerves  are 


^  See  table  on  the  preceding  page. 


Italicized  in  the  table. 


650 


THE  SPINAL  NERVES. 


made  particularly  prominent.  It  will  tend,  however,  to  sim- 
plify the  study  of  this  table,  if  you  will  compare  it  with  the 
one  adjoining,  Avhich  shows  the  construction  of  the  cervical 
plexus. 

This  plexus  is  formed  by  the  anterior  hranelies  of  these 
four  nerves,  so  that  you  will  find  the  same  nerves  mentioned 
in  both  tables  ;  since,  in  the  first  table,  a  nerve  may  be  men- 
tioned as  one  of  the  terminal  filaments  of  a  special  trunk, 
while,  in  the  second  table,  it  will  be  enumerated  as  one  of  the 
branches  of  the  plexus.  I  mention  this  point,  lest  some  con- 
fusion may  arise  in  your  minds  as  to  the  apparent  contradic- 
tion of  statement,  as  well  as  for  the  purpose  of  impressing  upon 
you  the  fact  that  a  branch  of  any  nerve  plexus  can  usually  be 
traced  as  arising  from  some  special  nerve  or  nerves,  which  as- 
sist to  form  that  plexus.  Thus  we  have  the  plirenic  nerve 
arising  by  three  heads  (third,  fourth,  and  fifth  cervical),  and, 
in  part,  a  branch  of  three  nerves ;  and  again,  the  communi- 
cans  noni  nerve^  which  goes  to  join  a  branch  of  the  hypo- 
glossal,' arises  by  two  heads  (second  and  third  cervical). 


THE   CERVICAL   PLEXUS   OF   i^^ERVES. 


Anterior     1 
branch  of  Ist 
Cervical 

nerve. 

r^ 

Anterior 

branch  of  2d 

Cervical 

i 

P 

nerve. 

.^. 

Anterior 

branch  of  8d 

Ceevtcal 

nerve. 

Anterior 

branch  of  4th 

Cervical 

s 

nerve. 

Sttperficial 
branches 
(integument- 
ary). 


Ascending      J 
set.  1 


Filament  to  attollens  aurem. 


Descending 

set. 


Aunculans  magnus. 

Superflcialis  colli Branch  to  platysma 


Supra-clavicular  branches. 


Sternal, 

Clavicular, 

Acromial, 


Deep 

bbanohes. 


Interoal  set.   - 


External  set.  J 


{Pneumoprastric, 
Hypo-glossal, 
Sympathetic. 
(  Eect.  cap.  ant.  major, 


(  Eect.  cap.  ant.  major. 
Muscular  <  Rect.  cap.  ant.  minor, 


Rect.  cap.  ant.  minor, 
\  Rect.  cap.  lateralis. 
Comnninicans  noni. 
Phrenic  . 


Muscular. 


Stemo-mastoid, 
Levator  anguli  scapulae, 
Trai>ezius, 
Scalenus  med. 


1,  Communicating  with  spinal  accessory  nerve. 

The  table  which  illustrates  the  method  of  construction  of 
the  cervical  ptexus  and  its  branches  of  distribution  may  be 

'  See  page  521  of  this  volume. 

'  The  loop  between  the  first  and  second  cervical  nerves  usually  gives  off  the  communi- 
cating branches  to  pneumogastric  and  hypo-glossal  nerves  and  to  the  superior  cervical 
ganglion  of  the  sympathetic,  while  the  third  and  fourth  cervical  nerves  give  communicat- 
ing branches  to  the  main  cord  of  the  sympathetic  nerve. 


THE  CERVICAL  PLEXUS   OF  I^EEVES. 


651 


studied  with,  some  advantage.  It  will  be  seen  that  the  plexus 
gives  off  two  distinct  sets  of  branches,  called  the  superficial 
and  the  deep,  since  the  former,  as  the  name  indicates,  are  all 


Fig.  192. — Supe>]ficial  branches  of  the  cervical  plexus.     (Hirschfeld.) 

1,  superficialis  colli ;  2,  2,  its  descending  branches ;  3,  its  ascending  branches  ;  4,  filaments 
of  anastomosis  with  the  facial ;  5,  auricularis  magnus ;  6,  its  parotid  branch ;  7,  its 
external  auricular  branch ;  8,  upper  part  of  the  same  branch,  crossing  the  iSbrous 
tissue  which  surrounds  the  root  of  the  helix,  and  supplying  the  external  surface  of 
the  pinna;  9,  internal  auricular  branch;  1(>,  filament  of  anastomosis  between  this 
branch  and  the  posterior  auricular  of  the  facial ;  11,  occipitalis  minor;  12,  branch  of 
communication  with  the  occipitalis  major ;  13,  accessory  occipitalis  minor ;  14,  branches 
to  the  integument  on  the  back  of  the  neck;  15,  supra-clavicular  branches,  sternal 
portion;  16,  clavicular  portion;  17,  supra-acromial  branches,  anterior  division;  18, 
posterior  division;  19,  branch  to  trapezius  from  cervical  plexus  ;  20,  branch  to  tra- 
pezius from  the  spinal  accessory,  and  anastomosing  with  the  preceding  ;  21,  branch 
to  the  levator  anguli  scapulae ;' 22,  trunk  of  the  facial;  23,  its  posterior  auricular 
branch  ;  24,  its  cervical  and  mental  branches. 


652 


THE  SPINAL  NERVES. 


cutaneous,  while  the  latter  are  distributed  to  muscles  and  ad- 
jacent nerves.  The  superficial  or  integumentary  set  comprises 
four  nerves,  three  of  which  ascend  toward  the  head,  while  the 
remaining  one  descends  toward  the  shoulder  ;  the  deep  set  is 
subdivided  into  branches  which  pass  toward  the  mesial  line  of 
the  trunk,  the  internal  set,  and  those  which  pass  away  from 
the  mesial  line,  the  external  set. 

SUPERFICIAL  BRANCHES   OF  THE   CERVICAL  PLEXUS. 

The  superficial  set  of  branches  is  of  the  greatest  impor- 
tance to  the  physician,  since  the  symptom  of  pain  is  often  a 
most  positive  guide  to  disease,  which  can  be  localized  by  a 
thorough  knowledge  of  the  nerves.     The  sub-occipital  nerve 


Fig.  193.—  The  nerve  supply  of  the  posterior  part  of  the  head.     (Hilton.)  j 

A,  region  supplied  by  the  great  occipital  nerve  ;  B,  region  supplied  by  the  small  occipital       j 
nerve;  C,  region  supplied  by  the  auriculo-temporal  nerve.  I: 


(first  cervical),  the  great  and  small  occipital  nerves  (branches 
of  the  second  cervical),  and  the  auricularis  magnus  (a  branch 
of  the  third  cervical)  are  all  distributed  to  the  integument  of 
the  scalp.,  in  the  posterior  region  of  the  head,  covering  the 
space  which  extends  from  the  neck  to  the  vertex  of  the  cra- 
nium.    The  plate  which  I  now  show  you  was  designed  by 


i; 


SUPERFICIAL  BRANCHES  OF  CERVICAL  PLEXUS.      653 

Hilton,'  to  illustrate  the  results  of  careful  experiment  as  to 
the  limits  of  the  cutaneous  distribution  of  each  of  these 
nerves. 

In  my  lecture  upon  the  distribution  of  the  fifth  cranial 
nerve,  I  called  your  attention  to  the  diagnostic  value  of  the 
cutaneous  distribution  of  the  nerves  of  the  ear.     It  may  be 


Fig.  194. —  The  nerve  supply  of  the  posterior  portion  of  head  and  neck.     (Modified  from 

Flower.) 

1,  region  supplied  by  the  great  occipital  nerve  ;  2,  region  supplied  by  the  auriculo-tempo- 
ral  nerve  ;  3,  region  supplied  by  the  small  occipital  nerve  ;  4,  region  supplied  by  the 
great  auricular  nerve  ;^5,  region  suppUed  by  the  third  cervical  nerve. 

weU  to  again  state  that  the  integument  of  the  pinna  is  sup- 
plied by  the  fifth  cranial,  the  great  auricular,  the  auricular 
branch  of  the  great  occipital,  and  the  small  occipital  nerves, ' 
and  to  impress  upon  you  that  the  limits  of  the  distribution  of 
each  are  now  so  well  defined  as  to  afford  a  clew,  in  many 
instances  where  pain  is  confined  to  this  region,  to  the  seat  of 
the  exciting  cause. 

^  Op.  cit. 

2  The  auricular  branch  which  Hilton  lays  stress  upon,  as  supplying  the  lobule  of  the 
ear  with  sensation,  may  be  given  off  either  by  the  anterior  or  posterior  division  of  the 
second  cervical  nerve.  In  the  table  of  the  distribution  of  the  cervical  nerves  I  have  put 
it  down  as  a  branch  of  the  great  occipital  nerve,  since  that  is  its  most  common  origin  ;  but 
it,  not  infrequently,  is  found  to  arise  from  the  small  occipital  nerve,  in  which  case  it 
would  be  derived  indirectly  from  the  anterior  division  of  the  second  cervical,  rather  thani 
from  the  posterior  division. 
44 


654  THE  SPINAL  NERVES. 

The  descending  branches  of  the  superficial  set  of  the  cervi- 
cal plexus  (supra-clavicular)  arise  from  the  third  and  fourth 
cervical  nerves,  and  are  distributed  to  the  integument  cov- 
ering the  lower  portion  of  tlie  neck  and  the  regions  of  the 
sternum,  clavicle,  and  acromion.  The  fact  that  the  filaments 
of  these  nerves  are  distributed  to  the  fascia  covering  the 
upper  portion  of  the  chesty  below  the  clavicle,  is  made  a 
point  of  diagnostic  importance  by  Hilton,  since  cases  of  dis- 
ease of  the  spinal  column,  in  the  region  of  escape  of  the  third 
or  fourth  cervical  nerves,  oi^  the  existence  of  pressure  along 
the  course  of  these  nerves,  have  been  suggested  to  him  by 
pain  in  this  region,  and  thus  detected  far  away  from  the  seat 
of  pain.  He  says  :  ''As  nothing  but  the  nerves  can  produce 
pain,  this  simple  distribution  ought  to  remind  us  of  the  fact 
that,  if  a  patient  complains  of  pain  in  this  part  of  the  chest, 
the  cause  may  lie  in  one  of  two  directions.  It  may  depend 
upon  disease  of  the  cervical  region  of  the  spine,  or  in  connec- 
tion with  some  disease  affecting  the  origin  of  the  upper  dorsal 
nerves." 

The  cervical  plexus  lies  upon  the  scalenus  medius  and  the 
levator  anguli  scapulae  muscles,  and  is  covered  by  the  stemo- 
mastoid  muscle  ;  hence,  all  of  its  superficial  branches  emerge 
from  beneath  the  posterior  border  of  this  latter  muscle.'  The 
muscles  which  the  plexus  supplies  directly  are  the  three 
which  lie  in  contact  with  it  and  the  trapezius.  JS^ow,  it  will 
be  remembered  that  the  trapezius  and  the  sterno-mastoid 
muscles  have  another  source  of  nervous  supply,  viz.,  the  spi- 
nal accessory  nerve.'  This  fact  suggests  that  these  muscles 
must  each  belong  to  two  groups  :  the  first,  those  which  con- 
trol  phonation  ; "  the  second,  those  which  insure  the  ordinary 
motions  of  the  neck.  In  the  same  way,  the  platysma  muscle, 
by  its  nervous  supply,  is  clearly  stamped  as  not  only  a  mus- 
cle of  the  neck,  but  also  one  of  expression^*  since  the  facial 
nerve  supplies  it,  as  well  as  the  cervical  plexus. 

'  See  figure  on  page  651  of  this  volume. 

*  See  page  508  of  this  volume. 

*  See  page  509,  previous  lecture,  upon  this  nerve. 

*  For  the  action  of  this  muscle  in  the  expression  of  melancholy,  cee  the  facial  nerve. 


COMMUmOANS  NONI  NERVE.  655 

DEEP   BEAKCHES   OF   THE   CERVICAL   PLEXUS. 

A  second  reference  to  the  table,  in  which  the  branches  of 
this  plexus  are  shown,  will  enable  you  to  recall  the  subdivis- 
ion of  the  deep  branches.  The  set  that  passes  toward  the 
mesial  line  of  the  body  comprises  the  muscular  filaments  to 
the  recti  muscles,  the  communicating  branches  to  adjacent 
nerves,  and  two  specially  named  trunks,  the  phrenic  and  com- 
municans  noni  nerves  ;  while  the  set  which  passes  toward  the 
periphery  of  the  neck  comprises  the  muscular  branches  to  the 
sterno-mastoid,  trapezius,  levator  anguli  scapulae,  and  the 
scalenus  medius,  and  communicating  filaments  to  adjacent 
nerves. 

The  filaments  of  communication  between  the  cervical 
plexus  and  the  pneumogastric,  hypo-glossal,  spinal  accessory, 
fifth  crania],  and  sympathetic  nerves,  have  been  already  dis- 
cussed in  connection  with  each  of  these  nerves.  They  all  in- 
dicate some  definite  purpose  on  the  part  of  Nature,  and  can 
best  be  reviewed  by  a  careful  perusal  of  the  notes  taken  by 
you  in  the  early  part  of  this  course  of  lectures. '  Many  of  the 
diagrams  of  the  special  nerves  mentioned  will  make  points 
clear  to  you  which  it  is  useless  to  repeat. 

The  communicans  noni  nerve^  whose  origin  can  be  traced 
to  two  filaments  connected  with  the  second  and  third  cervical 
nerves,  is  of  surgical  interest  from  the  relation  which  it  bears 
to  the  sheath  of  the  carotid  artery  ;  and  the  branches  which 
are  given  off  from  the  loop,  formed  by  its  junction  with  the 
descendens  noni  nerve,  can  be  seen  by  referring  to  the  dia- 
gram of  the  hypo-glossal  nerve."  Occasionally  this  nerve  is 
found  to  enter  the  sheath  of  the  carotid  artery,  and  to  anasto- 
mose with  the  descendens  noni  nerve  in  this  abnormal  situa- 

*  For  the  association  between  the  fifth  cranial  nerve  and  the  second  cervical  in  the  in- 
tegumentary supply  of  the  ear,  see  page  403 ;  between  the  facial  nerve  and  cervical 
nerves,  see  page  432 ;  between  the  pneumogastric  nerve  and  the  arcade  formed  by  the 
first  and  second  cervical  nerves,  see  diagram  of  pneumogastric  on  page  484  ;  between  the 
spinal  accessory  nerve  and  the  upper  cervical  nerves  and  its  physiological  bearing,  see 
pages  508  and  513;  finally,  between  the  hypo-glossal  nerve  and  the  communicans  noni 
nerve,  see  plate  on  page  521  of  this  volume. 

^  See  page  521  of  this  volume. 

/ 


656  THE  SPINAL  NERVES. 

tion.'  From  tlie  loop  whicli  it  helps  to  form,  filaments  are 
given  to  the  sterno -thyroid,  sterno-hyoid,  and  both  bellies  of 
the  omo-hyoid  muscle.  Thus  these  muscles  are  placed  under 
the  control  of  two  nerves  ;  the  one  (communicans  noni  neiTe) 
enabling  them  to  act  in  harmony  with  the  muscles  of  the  neck, 
while  the  other  (descendens  noni  nerve)  enables  them  to  assist 
in  depressing  the  larynx  and  the  hyoid  bone,  after  the  bolus 
of  food  has  passed  the  isthmus  of  the  fauces,  thus  acting  in 
harmony  with  the  tongue,  which  is  also  supplied  by  the  hypo- 
glossal nerve.  We  can  perceive,  therefore,  that  these  mus- 
cles are  concerned  in  two  distinct  functions — the  movements 
of  the  neck  and  the  act  of  deglutition  and  speech ;  hence  they 
must  of  necessity  be  separately  supplied  by  the  nerves  of  the 
neck  and  that  of  the  tongue,  in  order  to  properly  perform  the 
two  acts  independently  of  each  other. 

The  pJirenic  nerve,  called  also  the  '^internal  respiratory 
nerve  of  Bell," "  arises,  by  three  heads,  from  the  third,  fourth, 
and  fifth  cervical  nerves.  Its  course  and  distribution  give  it  a 
surgical  as  well  as  a  physiological  importance.  It  lies  in  front 
of  the  scalenus  anticus  muscle,  and  thus  in  relation  to  the 
second  portion  of  the  subclavian  artery ;  lower  in  the  neck, 
it  passes  between  the  subclavian  vein  and  the  first  portion  of 
the  subclavian  artery ;  when  it  has  entered  the  superior  open- 
ing of  the  chest,  its  course  upon  the  left  side  of  the  body  lies  in 
front  of  the  arch  of  the  aorta  and  the  pulmonary  artery,  but 
upon  the  right  side  the  nerve  passes  external  to  the  superior 
vena  cava  and  the  right  innominate  vein  ;  each  nerve  crosses 
in  front  of  the  root  of  the  corresponding  lung,  gives  off  twigs 
to  the  pericardium  and  pleura,  and  perforates  the  diaphragm, 
to  be  distributed  to  its  under  surface.  Both  nerves  give  fila- 
ments to  the  phrenic  plexus  of  the  sympathetic,  and  the  right 
nerve  furnishes  some  filaments  to  the  diaphragmatic  ganglion. 

The  distribution  of  the  phrenic  nerves  to  the  diaphragm 
is  mentioned  by  Hilton"  as  one  of  the  simple  devices  of 

^  It  is  sometimes  found  beneath  the  jugular  vein,  and,  occasionally,  in  front  of  it. 
^  Tliis  name  was  applied  to  the  phrenic  nerve  by  Bell,  since  it  passes  internally  to  the 
chest  wall,  and  assists  in  the  physiological  act  of  respiration.  ^  Op.  ciL 


THE  PHRENIC  NERVE.  657 

Nature  to  guard  the  nerves  from  injury.  I  quote  from  his 
excellent  treatise  as  follows:  "As  a  rule,  nerves  enter  the 
muscles  where  they  will  be  most  secure  from  pressure,  and  it 
is  curious  to  observe  how  careful  Nature  has  been  in  this  re- 
spect to  guard  one  of  the  most  important  nerves  in  the  body. 
The  phrenic  nerves  (our  life  hangs  on  these  threads),  after 
passing  through  the  chest,  traverse  the  diaphragm  and  dis- 
tribute their  branches  to  the  under  surface  of  the  diaphragm, 
and  are  so  situated  that  they  can  not  be  compressed  during 
respiration.  If  they  were  situated  upon  the  upper  surface 
of  the  diaphragm,  where  there  is  a  constant  and  forced  con- 
tact between  the  base  of  the  lung  and  the  superior  aspect  of 
the  diaphragm,  and  especially  so  during  a  retained  inspira- 
tion, it  is  obvious  that  the  filaments  of  the  phrenic  nerve 
would,  under  such  circumstances,  be  exposed  or  subjected  to 
compression,  and  the  action  of  the  diaphragm  would  be  dan- 
gerously interfered  with.  The  nerves  are,  however,  distrib- 
uted to  the  under  or  concave  surface  of  the  diaphragm  ;  the 
whole  tendency  of  gTavitation  being  to  remove  the  liver,  the 
stomach,  and  the  spleen  away  from  them,  so  as  to  enable  the 
nerves  to  carry  on  their  influence  to  the  diaphragm  unmo- 
lested." 

How  extraordinary  is  it  that  the  phrenic  nerve  (a  nerve 
so  important  to  life)  can  pass  through  the  chest  between  the 
dilated  heart  and  the  inflated  lungs,  and  yet,  as  far  as  we 
know,  never  receive  any  untoward  influence  from  pressure ! 
It  is  true  that  the  lungs  have  a  remarkably  definite  concave 
form  toward  the  heart,  arching  over  the  course  of  the  phrenic 
nerve  ;  but,  when  the  lungs  are  emphysematous,  it  seems 
quite  probable  that  these  nerves  might  suffer  from  pressure, 
and  cause  some  difficulty  in  breathing.  When  extravasation 
of  air  occurs  from  rupture  of  the  trachea  or  a  large  bronchial 
tube,  the  patient  dies  rapidly  from  extreme  shortness  oi 
breath ;  and  this  can  be  explained  by  the  fact  that  the  air 
enters  the  tract  of  the  phrenic  nerve,  thus  causing  extreme 
pressure  and  death  from  paralysis  of  the  diaphragm. 

The  distribution  of  the  phrenic  nerves  to  the  pericardium 


658  THE  SPINAL  NERVES. 

seems  to  warrant  the  supposition  of  Hilton  that  the  pericardi- 
um may  be  considered  as  a  portion  of  the  fascial  tendon  of 
the  diaphragm,  since  it  is  closely  identified  with  it,  and  is  acted 
upon  by  it,  at  all  times.  It  may  also  be  considered  as  prob- 
able that  the  phrenic  nerves  are  endowed  with  some  sensory 
filaments,'  by  communication  with  other  nerves  ;  and  the 
analogy  of  the  pericardium  and  diaphragm  to  a  joint,  so  beau- 
tifully pointed  out  by  Hilton,  where  the  fibrous  layer  of  the 
heart  sac  resembles  the  capsular  ligament,  the  serous  layer 
the  synovial  membrane,  and  the  diaphragm  the  muscle  which 
moves  it,  is  confirmed  by  the  similarity  of  nervous  distribu- 
tion.'' We  know  that  in  pericarditis  the  patients  complain 
of  a  sense  of  constriction  and  tightness  in  the  chest,  and  are 
afflicted  with  a  shortness  of  breath  ;  we  also  see  an  inflamed 
condition  of  this  membrane  creating  a  spasm  of  the  dia- 
phragm, precisely  as  the  nerves  of  an  inflamed  joint  create  a 
contraction  of  the  adjacent  muscles  ;  and  why  are  we  not 
justified  in  attributing  these  symptoms  to  the  analogy  which 
anatomy  so  well  sustains,  and  the  axiom  of  nerve  supply  to 
joints  seems  to  confirm  ? 

CLINICAL  POINTS   PERTAINING  TO  THE  CERVICAL  NERVES. 

The  distribution  of  the  branches  of  the  upper  four  cervical 
nerves,  which  have  been  considered  in  some  detail  in  the  pre- 
ceding lecture,  may  be  said  to  furnish  sensory  filaments  to 
the  skin  covering  the  occipital  region  as  high  as  the  vertex, 
and  the  integument  of  the  neck,  in  its  posterior  and  lateral 
aspects,  as  far  down  as  the  shoulder.  The  muscular  fila- 
ments given  off  by  these  nerves  have  little  clinical  interest, 
since  the  diseases  which  are  most  frequently  met  are  confined 
chiefly  to  the  great  occipital  nerve,  the  cutaneous  branches  of 
the  neck,  and  the  phrenic.     We  will  consider,  therefore,  only 

*  Luschka  and  Henle  regard  the  phrenic  as  a  mixed  nerve.  This  view  seems  to  be 
sustained  by  cases  of  neuralgia  (as  reported  by  Falot,  Peter,  Erb,  and  others)  wliich  have 
been  produced  by  irritation  of  this  nerve.  The  development  of  Luschka's  ganglion  upon 
this  nerve  seems  to  be  a  further  evidence  of  the  existence  of  sensory  as  well  as  motor 
fibers  within  the  phrenic. 

*  See  axioms  of  nerve  distribution,  on  page  645  of  this  volume. 


GERVICO-OCGIPITAL  NEURALGIA.  659 

that  type  of  neuralgia  which  affects  the  regions  of  the  occi- 
put and  neck  called  '^cervico-occipital  neuralgia"  and  the 
nervous  disorders  dependent  upon  the  distribution  of  the 
phrenic  nerve. 

Cervico-occipital  Neuralgia, — This  is  a  rare  form  of  dis- 
ease. It  is  induced  by  exposure,  perhaps,  more  frequently 
than  by  any  other  cause.  It  may  be  also  the  result  of  dis- 
eases of  the  spinal  column,  such  as  periostitis,  spondylitis  of 
the  cervical  region,  tumors,  and  injuries ;  also  of  wounds  of 
the  nerves,  irritation  of  the  cervical  portion  of  the  spinal 
cord,  enlarged  lymphatic  glands,  neuromata,  tumors  of  the 
neck  or  spinal  cord,  foreign  bodies,  etc.  Aneurism  of  the  ver- 
tebral artery  has  been  known  to  produce  it. 

The  pain  of  this  type  of  neuralgia  may  be  continuous  or 
paroxysmal,  and  either  circumscribed  or  widely  diffused  over 
the  entire  occipital  and  cervical  regions.  In  severe  parox- 
ysms of  pain,  the  movements  of  the  head  and  the  acts  of 
speech  and  mastication  may  be  rendered  difficult  or  impossi- 
ble. Movements  of  the  head,  and  the  acts  of  laughing,  sneez- 
ing, and  mastication,  often  tend  to  excite  the  paroxysms  of 
pain.' 

As  in  many  other  forms  of  neuralgia,  certain  points  of  ex- 
treme tenderness,  the  ''puncta  dolorosa  of  Yalleix,"  may  be 
detected,  and  these  may  be  distinctly  located  at  the  following 
spots : 

1.  Where  the  great  occipital  nerve  escapes  at  the  occiput^ 
between  the  mastoid  process  and  the  first  cervical  vertebra. 

2.  Where  the  branches  of  the  cervical  plexus  escape 
around  the  posterior  border  of  the  sterno-mastoid  muscle,  in 
the  middle  point  of  the  neck,  (This  point  of  tenderness  may 
be  absent.) 

3.  Where  the  small  occipital  and  great  auricular  nerves 
escape  to  the  surface,  just  behind  the  mastoid  process. 

4.  Where  the  frontal  branch  of  the  trigeminus,  the  great 
auricular,  and  the  occipital  nerves  meet,  over  the  situation  of 
the  parietal  protuberance. 

*  The  fixed  attitude  in  which  this  class  of  patients  hold  their  heads  is  very  characteristic. 


660  THE  SPINAL  NERVES, 

5.  Where  the  auricular  nerves  meet,  on  the  concha  of  the 
ear.' 

It  is  the  detection  of  these  points  of  tenderness '  that  as- 
sists the  diagnostician  to  discriminate  between  rheumatic 
pains  and  those  of  a  purely  neuralgic  character,  and  it  will 
usually  be  observed  that  the  paroxysms  of  pain  start  from 
these  points  of  tenderness.  This  type  of  neuralgia  is  often 
associated  with  a  similar  affection  of  the  fifth  nerve,  and  occa- 
sionally of  the  brachial  plexus.  It  may  be  followed  by  nu- 
tritive disturbances,  such  as  falling  out  of  the  hair  over  the 
affected  region.  The  duration  of  this  form  of  neuralgic  pain 
varies  from  a  few  days,  to  weeks,  months,  or  even  years,  de- 
pending somewhat  upon  the  exciting  cause. 

DISORDERS  OF  THE   PHRENIC   NERVE. 

The  phrenic  nerve  may  manifest  the  effects  of  irritation  in 
the  form  of  neuralgia,  clonic  spasm  (hiccough),  and  tonic 
spasm  of  the  diaphragm  ;  and  also  that  of  a  more  serious  im- 
pairment of  its  function,  as  diaphragmatic  paralysis. 

Diaphragmatic  neuralgia  seems  to  be  manifested  (in 
those  few  reported  cases  which  are  well  authenticated)  by  a 
pain  which  begins  in  the  base  of  the  thorax,  at  the  point  of 
insertion  of  the  diaphragm,  and  which  radiates  upward  into 
the  territory  of  the  shoulder  and  neck,  which  is  supplied  by 
the  cutaneous  branches  of  the  cervical  plexus.  The  points  of 
tenderness  which  exist  in  this  affection  seem  to  be  most 
marked  (1)  in  the  region  of  origin  of  the  phrenic,  near  to  the 
spinous  processes  of  the  middle  three  cervical  vertebrae ;  (2) 
over  the  nerve,  as  it  enters  the  supra-clavicular  fossa  ;  and  (3) 
at  the  anterior  insertions  of  the  diaphragm,  between  the 
seventh  and  the  tenth  ribs.  It  is  claimed  by  Erb  that  a  point 
of  tenderness  can  often  be  detected  over  the  cartilage  of  the 
third  rib,  but  I  find  it  difiicult  to  explain  this  symptom  on 

'  This  point  of  tenderness  is  often  absent. 

'  It  will  be  noticed  that  these  points  of  circumscribed  tenderness  correspond,  in  every 
instance,  to  the  approach  of  some  nerve  or  its  terminal  filaments  to  the  surface  of  the 
body.  The  points  of  subdivision  of  a  nerve  trunk  into  its  branches  of  distribution  are  often 
the  scat  of  this  excessive  sensitiveness  to  pressure. 


J 


DISORDERS  OF  TEE  FHRENIG  NERVE.  661 

anatomical  grounds,  although  its  presence  in  some  cases 
seems  to  be  proven. 

The  pain  of  phrenic  neuralgia  is  more  or  less  continuous, 
since  the  incessant  movements  of  the  diaphragm  tend  to  ex- 
cite it ;  but  exacerbations,  of  a  character  closely  resembling 
distinct  paroxysms,  are  often  observed,  when  the  pain  be- 
comes lancinating  and  causes  impeded  respiration.  The 
efforts  of  coughing,  sneezing,  or  exertion  of  any  kind  which 
involves  the  muscles  of  the  trunk,  are  rendered  difficult  and 
painful.  Muscular  debility  and  tremblings  in  the  upper  ex- 
tremity are  sometimes  present.  As  this  type  of  neuralgia 
often  accompanies  organic  lesions  of  the  heart,  concomitant 
phenomena,  such  as  cardiac  palpitation,  angina  pectoris,  etc., 
may  coexist. 

Although  phrenic  neuralgia  is  not  infrequently  an  inde- 
pendent and  primary  disease  in  the  anaemic  and  nervous  class 
of  patients  (especially  after  exposure  to  cold,  dampness,  etc.), 
still  it  is  far  more  commonly  met  with  as  a  concomitant  affec- 
tion of  some  other  disease.  It  is  therefore  always  best  to 
look  for  the  existence  of  heart  lesions,  aneurism  of  the  medi- 
astinum, Basedow's  disease,  angina  pectoris,  and  diseases  of 
the  liver  and  of  the  spleen,  since  they  may  explain  the 
phrenic  symptoms  and  modify  the  prognosis. 

The  close  resemblance  which  this  type  of  neuralgia  has  to 
attacks  of  diaphragmatic  pleurisy,  pericarditis,  uncomplicated 
angina  pectoris,  and  gastralgia,  makes  the  situation  of  the 
diagnostic  points  of  tenderness  an  important  factor  in  the 
discrimination. 

Violent  spasmodic  contractions  of  the  diaphragm,  termed 
clonic  spasm  or  "  MccougTi^^^  are  accompanied  by  an  inspi- 
ratory sound,  interrupted  by  a  sudden  spasm  of  the  con- 
strictors of  the  glottis,  and  followed  by  a  short  expiration. 
The  symptoms  produced  by  this  condition  depend  upon  the 
intensity  and  duration  of  the  attack.  In  severe  cases  there 
may  be  pain,  embarrassment  of  speech,  dyspnoea,  and  retrac- 
tion of  the  epigastric  region.  The  causes  of  hiccough  may  be 
classed  under  three  heads :  1,  those  of  direct  irritation  of  the 


662  THE  SPINAL  NERVES. 

phrenic,  as  occurs  in  the  case  of  mediastinal  tumors,  aneurism 
of  the  arch,  pneumonic  or  pleuritic  inflammation,  pressure 
from  pleuritic  effusion,  etc.  ;  2,  those  of  a  reflex  nature,  as 
in  diseases  of  the  urinary  organs,  the  uterus,  and  the  intestinal 
tract  and  the  liver ;  the  irritation  of  biliary  or  renal  calculi ; 
irritation  of  the  pharynx,  oesophagus,  and  stomach ;  and  dis- 
eases of  the  peritonaeum  j  3,  those  of  central  origin,  as  occurs 
in  hysteria,  local,  brain,  or  spinal  diseases,  blood  poisoning 
(as  in  the  fevers,  cholera,  dysentery,  etc.),  after  emotional 
excitement,  and  from  the  general  anaemia  of  nerve  centers 
after  haemorrhage.  You  can  see  from  this  list  of  causes  that 
the  symptom  of  hiccough,  if  occurring  late  in  connection  with 
any  form  of  disease,  may  be  a  most  serious  symptom. 

Tonic  spasm  of  the  diaphragm  is  a  rare  form  of  disease. 
It  has  been  called  "diaphragmatic  tetanus."  The  symptoms 
of  this  obscure  affection  have  been  developed  through  the  ex- 
periments of  Duchenne  upon  animals,  and  the  careful  obser- 
vations of  Valette,  Fischl,  Yigla,  Oppolzer,  Duchenne,  and 
others  upon  man. 

The  patient  is  at  once  markedly  asphyxiated,  the  liver  is 
displaced  downward  by  the  contracted  diaphragm  ;  the  lower 
half  of  the  thorax  is  enlarged  and  rendered  immovable  ;  the 
inspirations  are  extremely  short,  and  the  expirations  are  noisy 
and  prolonged.  The  face  shows  the  evidences  of  anxiety  and 
cyanosis  ;  the  pulse  is  slow  and  diminished  in  volume ;  and 
the  voice  is  monotonous  in  tone,  and  often  interrupted. 
Acute  pains  pervade  the  lower  regions  of  the  thorax,  and 
shoot  over  the  epigastrium.  While  one  case  seems  to  have 
ended  fatally,  all  other  reported  cases  have  recovered. 

Paralysis  of  the  diaphragm  may  occur  as  a  symptom  of  I 
hysteria,  lead  poisoning,  the  advanced  stages  of  progressive 
muscular  atrophy,  and  paralysis  of  the  bulbar  nuclei.  It 
may  be  also  produced  by  the  extension  of  inflammation  in 
cases  of  pleurisy  or  peritonitis,  thus  creating  exudation  or 
suppuration  in  the  substance  of  the  muscle. 

When  this  condition  is  fully  developed,  the  abdominal 
walls  are  retracted  during  each  inspiratory  effort,  while  the 


TEE  FOUR   LOWER   CERVICAL  NERVES.  663 

lower  portion  of  the  thorax  is  distended  ;  in  expiration,  how- 
ever, the  hypochondriac  region,  as  well  as  the  epigastric, 
sinks  in,  while  the  chest  becomes  diminished  in  its  capacity. 
The  respiration  becomes  slow  and  difficult,  and  speaking  or 
muscular  movements  increase  the  embarrassment  of  this  func- 
tion. The  voice  is  usually  enfeebled,  and  may  be  entirely 
lost.  The  liver  tends  to  rise  in  the  chest,  during  inspiration, 
rather  than  to  be  displaced  downward  into  the  abdomen. 

THE  FOUK  LOWER   CERVICAL  NERVES. 

As  was  the  case  with  the  four  upper  nerves,  which  escape 
from  the  cervical  portion  of  the  spinal  cord,  the  four  lower 
divide  into  anterior  and  posterior  divisions,  as  soon  as  they 
escape  from  the  spinal  foramina.  The  anterior  divisions  of 
each  join  to  form  the  brachial  plexus  of  nerves,  which  sends 
filaments  of  distribution  to  the  neck,  shoulder,  upper  ex- 
tremity, and  side  of  the  thorax.  The  posterior  divisions  do 
not  form  a  plexus,'  but  are  separately  distributed  to  the  semi- 
spinalis,  complexus,  splenius,  and  trapezius  muscles,  and  then 
send  twigs  to  the  integument'  over  these  muscles,  viz.,  over 
the  region  of  the  spine  in  the  lower  part  of  the  neck. 

The  following  table '  will  assist  you  in  mastering  the  con- 
struction of  the  brachial  plexus,  and  in  understanding  the 
plates  of  that  complicated  mesh-work  of  nerves.  It  may  be 
well  to  remark  that  the  diagrams  of  this  plexus  are  seldom 
alike  in  the  works  of  any  two  authors ;  since,  if  they  are 
intended  to  be  accurate  representations  of  the  parts,  they  nat- 
urally tend  to  show  the  great  dissimilarities  which  exist  in 
the  union  of  the  different  nerves  which  help  to  form  it,  while, 
if  purely  diagrammatic,  no  two  authors  would  naturally  fol- 
low the  same  schematic  plan.  Notwithstanding  the  dissimi- 
larities which  exist,  there  are,  however,  points  of  resemblance 

*  In  the  case  of  the  three  upper  cervical  nerves,  an  anastomosis  of  the  posterior  di- 
visions occurs,  to  which  Cruveilhier  applies  the  term  "  posterior  cervical  plexus." 

*  See  researches  of  Cruveilhier,  Sappey,  Hirschfeld,  and  others, 

3  Modified  from  tables  in  "  The  Essentials  of  Anatomy "  (Darling  and  Ranney). 
G.  P.  Putnam's  Sons,  New  York,  1880. 


664 


THE  SPINAL  NERVES. 


in  them  all,  which  consist  in  the  delineation  of  an  outer  cord 
formed  by  the  fifth,  sixth,  and  seventh  cervical  nerves ;  an 
inner  cord  formed  by  the  eighth  cervical  and  first  dorsal 
nerves  ;  and  a  middle  cord  formed  by  a  branch  from  both  the 
outer  and  the  inner,  which  subsequently  unite. 


THE  BRACHIAL  PLEXUS. 


Anterior 
division  of 
6th  Cee- 

VICAL 

nerve. 


Anterior 
division  of 
6th  Cer- 
vical 

nerve. 


Anterior 
division  of 
7th  Cer- 
vical      . 
nerve.     J 


Anterior 
division  of 
6tu  Cer- 
vical 
nerve. 


Form 
outer 
cord  of 


y   BRACHIAL 
PLEXUS. 


Branches 

above  the 

clavicle. 


Form    in- 
y     ner  cord 


Anterior 
division  of 

l!:T  Dor- 
sal nerve.  J 


of. 


f  Posterior  thoracic  (eactemal  respiraior?/  nerre 
of  Bell)  distributed  to  the  serratus  inagnus 
muscle. 

(  Shoulder  joint. 

f  Rhomboidei  muscles  (from  6th 
cervical  nerve), 
Subclavius  (from  5th  and  6th 
I      cervical  nerves), 
Muscular  (8)  \  Scaleni  muscles  j  ^^^5^?' l*^' 
Longus  colli       i  apd  &th  cer- 
^  {   vical  nerves), 

I  Levator  anguli  scapulae  (from 
(.      5th  cervical  nerve). 

i_  Communicating  branch  (to  phrenic  nerve). 


f  Internal  anterior  thoracic, 
I  Internal  cutaneous, 
From  inn&r  J  Lesser      internal      cutaneous 

cord 1      (  Wriaberg's  nerve). 

Inner  head  of  median  nerve, 
[  Ulnar  nerve. 

External  anterior  thoracic, 


Branches  , 


Outer  head  of  median  nerve. 


1st  subscapnlar  nerve, 
v-^rv,  ^^of^    I  2d  subscapular  nerve. 
From  poste-  J  g^  su^sea  lular  nerve 
I      ^^'^^  '^^^-  1  Musculo-spiral  nerve, 
l^  \,  Circumflex  nerve. 


This  table  and  the  diagram  (after  Gray)  shown  on  the  next 
page  will  help  to  make  clear  the  method  of  construction  of 
the  brachial  plexus,  and  the  main  branches  which  are  given 
off  from  its  different  portions.  It  will  be  perceived  that  the 
branches  of  distribution  are  subdivided  into  two  sets :  those 
given  off  above  the  line  of  the  clavicle  and  those  given  off 
below  that  line.  The  former  set,  if  traced,  will  be  seen  to 
supply  the  muscles  of  the  scapular  region,  some  of  the  mus- 
cles of  the  neck,  the  serratus  magnus  (a  muscle  of  respiration), 
and  the  subclavius.  The  branch  of  communication  which 
helps  to  complete  the  formation  of  the  phrenic  nerve  is  also 
shown  to  arise  from  the  fifth  cervical  nerve.     The  branches 

'  The  posterior  cord  of  the  brachial  plexus  is  formed  by  a  branch  from  both  the  inner 
and  outer  cord. 


THE  BRACHIAL  PLEXUS  OF  NERVES. 


665 


wMcli  are  given  off  below  the  line  of  the  clavicle  are  distrib- 
uted to  the  muscles  of  the  upper  extremity,  and  will  be  con- 
sidered in  detail  in  subsequent  tables  and  diagrams. 


5^ 
Cervical.  N 


Fasciculus  FROM  4-Cerv./V. 

Communicating  with  Phrenic, 

Rhomboid. 


Supra  Scapular. 
■LINE  OF  Clavicle. 


Dorsal 


Fig.  195. — A  diagram  of  the  brachial  plexus  audits  branches.     (Gray.) 

Varieties,  more  apparent  than  real,  are  frequently  met 
with  in  the  formation  of  this  plexus, '  resulting  from  the  cor- 
responding increase  or  diminution  in  the  size  of  the  above 
anastomotic  branches,  and  of  the  portion  of  the  posterior  cord 
which  is  given  off  by  the  seventh  cervical  nerve.  The  poste- 
rior cord  may  be  occasionally  formed  by  the  seventh  cervical 
nerve  alone  ;  while  it  may  in  some  instances  be  formed  by  two 
bands,  arising  from  the  fifth  and  sixth  nerves,  withoi^t  any 
assistance  from  the  seventh  nerve.     Other  variations  may  re- 

^  The  dissections  and  paper  of  K.  C.  Lucas  upon  this  point  ("  Guy's  Hospital  Reports  " 
18Y5)  and  the  description  of  this  plexus  by  Henle  seem  to  confirm  each  other  as  regards 
the  abnormalities  of  its  formation. 


66Q 


THE  SPINAL  NERVES. 


suit  from  the  branches  of  the  plexus  being  given  off  at  a  higher 
or  lower  point  than  usual,  and  also  by  the  seventh  nerve  join- 
ing the  plexus  at  a  higher  or  lower  level  than  normal. 

The  brachial  plexus,  as  a  whole,  is  broad  between  the  mid- 
dle and  anterior  scaleni  muscles,  at  which  point  it  lies  imme- 
diately above  the  second  portion  of  the  subclavian  artery  ;  it 
is  contracted  in  size  opposite  the  clavicle,  where  the  outer 
and  inner  cords  lie  on  the  outer  side  of  the  third  portion  of 
the  subclavian  artery ;  and,  in  the  axilla,  it  again  expands, 
the  three  cords  bearing  the  relation  to  the  second  portion  of 


Fig.  196. — Anterior  branches  of  the  four  last  cervical  and  the  first  dorsal  nerves.     (Hirsch- 

feld.) 

1,  anterior  branch  of  the  fifth  cervical,  ordinarily  united  with  the  sixth  cervical  before  di- 
viding; 2,  anterior  branch  of  the  sixth  cervical;  3,  anterior  branch  of  the  seventh 
cervical ;  4,  anterior  branch  of  the  eighth  cervical ;  5,  anterior  branch  of  the  first 
dorsal ;  6,  origin  of  the  subclavian  nerve ;  7,  posterior  thoracic  arising  from  the 
fifth,  sixth,  and  seventh  cervical  nerves ;  8,  supra-scapular ;  9,  common  trunk  of 
of  the  branches  supplying  the  levator  anguli  scapulae  and  the  rhomboidei ;  10,  superior 
subscapular;  11,  anterior  thoracic  branches;  12,  inferior  subscapular:  13,  long  sub- 
scapular; 14,  separate  branch  to  the  teres  major;  15,  circumflex  nerve;  16,  lessor 
internal  cutaneous;  17,  internal  cutaneous ;  18,  ulnar;  19,  median;  20,  musculo- 
apiral;  21,  radial. 

the  axillary  artery  which  their  names  designate.  Thus  it  will 
be  perceived  that  this  plexus  has  important  surgical  relations 
with  the  last  two  portions  of  the  subclavian  artery  and  the 
two  upper  portions  of  the  axillary  artery.  The  terminal 
branches  of  the  three  cords  are  also  in  relation  with  the  third 


J 


ABNORMALITIES   OF  THE  BRACHIAL  PLEXUS. 


^(^7 


portion  of  the  axillary  artery,  since  they  almost  entirely  sur- 
round it. 

The  preceding  cut  of  the  brachial  plexus,  taken  from  the 
superb  anatomical  work  of  Sappey,  will  enable  you  to  con- 


FiG.  19*7. —  Collateral  branches  of  the  brachial  plexus.  (Hirschfeld.) 
1,  arcade  formed  by  the  anastomosis  of  the  descending  branch  of  the  hypo-glossal  with 
the  internal  descending  branch  of  the  cervical  plexus ;  2,  pneumogastric  nerve ;  3, 
phrenic  nerv  e ;  4,  anterior  branch  of  the  fifth  cervical  pair ;  5,  anterior  branch  of 
the  sixth  cervical  pair  ;  6,  anterior  branch  of  the  seventh  cervical  pair  ;  7,  8,  anterior 
branch  of  the  eighth  cervical  pair  and  first  dorsal  pair ;  9,  9,  branch  to  the  subcla- 
vius  muscle  ;  10,  long  thoracic  nerve  ;  11,  nerve  to  the  pectoralis  major  giving  off  a 
filament  to  anastomose  with  that  supplying  the  pectoralis  minor;  12,  supra-scapular 
nerve  passing  under  the  coracoid  ligament;  13,  nerve  supplying  the  pectoralis  minor 
muscle ;  14,  branch  supplying  the  pectoralis  minor  muscle  given  off  from  the  one 
which  supplies  the  pectoralis  major  muscle ;  15,  inferior  branch  of  the  subscapularis ; 
16,  nerve  to  the  teres  major  muscle;  lY,  nerve  to  the  latisslmus  dorsi  muscle;  18, 
accessory  branch  of  the  internal  cutaneous;  19,  an  anastomosis  of  this  branch  with 
the  perforating  branch  of  the  second  intercostal  nerve ;  20,  ramification  of  the  acces- 
sory branch  of  the  internal  cutaneous  nerve;  21,  internal  cutaneous  nerve  ;  22,  ulnar 
nerve ;  23,  median  nerve ;  24,  musculo-cutaneous  nerve  ;  25,  musculo-spiral  nerve. 

trast  the  diagrammatic  plate  of  Gray '  with  the  actual  repre- 
sentation of  the  parts  under  consideration. 

'  See  page  666  of  this  volume. 


668 


THE  SPINAL  NERVES. 


COMMUNICATIONS   OF  THE   PLEXUS. 

The  brachial  plexus  coinmuiiicates  with  the  cermcal  plexus 
by  a  branch  which  joins  the  fourth  and  fifth  nerves,  and  by- 
one  head  of  the  phrenic  nerve.  It  also  sends  filaments  to  the 
middle  and  inferior  cermcal  ganglia  of  the  sympathetic, 
and,  in  this  way,  anastomoses  with  the  corresponding  filaments 
of  the  first  dorsal  nerve. 

NERVES   OF   THE   UPPER  EXTREMITY. 


BRANCHES  OF  THE   OUTER   CORD   OF  THE  BRACHIAL  PLEXUS.* 


Branches  of 

the  OUTER 

CORD  of  the 
brachial 
plexus. 


(1)  External 
anterior  tho- 
RACIC  


Pectoralis  major. 


(2)  External 

or    MUSCDLO-CU- 

taneous 


'  Muscular 
branches. 


Anterior 
branch. 


Posterior 
branch. 

Articular 
branch. 


In  fore- 
arm. 


(3)  Median. 


In  the 
hand. 


Coraco-brachialis, 

Biceps, 

Brachialis  anticus. 

Litegument  of  the  front  of  forearm, 

Integument  of  ball  of  thumb, 

Joins  with  the  radial  nerve. 
'  Integument  of  radial  side  of  back  of  fore- 
arm. 

Joins  with  the  radial  nerve. 

Joins  with  the  external  cutaneous  branch 
of  the  musculo-spiral  nerve. 

[  To  elbow  joint. 

f  Pronator  radii  teres, 
Flexor  carpi  radialis, 
Palmaris  longus, 
Flexor  subiimis  digitorum. 
Flexor  longus  pollicis, 
Flexor   profundus   digitorum 

(its  outer  half), 
Pronator  quadratus. 


Muscu- 
lar. 

Anterior 
interosse- 
ous. 


Palmar    i  Integument  of  palm, 
-    ■<  Integument 


cutane 
ous. 


External 
branch. 


Internal 
branch. 


of    ball    of    the 
thumb. 

Abductor  pollicis, 

Opponens  pollicis, 

Flexor  brevis  pollicis  (outer 
head), 

Digital  to  thumb  (palmar  sur- 
face), 

Digital  to  index  finger  (outer 
side). 
'  Digital  to  contiguous  sides  of 
index,  middle,  and  ring  fin- 
gers, 

Filaments  to  the  two  outer 
lumbricales  muscles. 


»  Modified  from  a  table  in  "  The  Essentials  of  Anatomy  "  (Darling  and  Ranney).    G.  P. 
Putnam's  Sons,  New  York,  1880. 


^i 


BRANCHES  OF  THE  BRACHIAL  PLEXUS. 


669 


BRANCHES   OF   THE   INNER   CORD   OF  THE   BRACHIAL   PLEXUS. 


Branches  of 

the    INNER 

CORD  of  the 
brachial 
plexus. 


(1)  Internal  an- 
terior THORAC- 
IC. 


(2)  Internal  cu- 
taneous. 


(3)  Lesser  in- 
ternal cuta- 
neous. (Wris- 
berg.) 


(4)  Ulnar. 


Anterior 
branch. 


ior    \ 
ich.  1 


Posterior 
branch. 


Both  pectoral  muscles  (since  its  filaments  lie  above 
and  underneath  the  pectoralis  minor  muscle). 

Integument  of  the  anterior  surface  of  the 
inner  side  of  the  forearm  as  low  as  the 
wrist. 
Integument  of  the  posterior  surface  of  the 
inner  side  of  the  forearm  to  near  the 
wrist. 
May,  occasionally,  be  wanting  (the  intercosto-humeral 

nerve  taking  its  place). 
Integument  of  the  posterior  surface  of  the  lower  third 
of   the   arm  (joining  with   the   intercosto-humeral 
nerve  and  the  posterior  branch  of  the  internal  cu- 
taneous nerve). 

f  Articular  (to  elbow  joint) — several  small 
filan^nts. 

Flexor  carpi  ulnaris, 
Inner  half  oi  flexor  pro- 
fundus digitorum. 
Integument    of    front    of 
wrist  and  palm  of  hand, 
r  Integument    at    back    of 
I       wrist  and  one  and  one 
i       half    fingers    on   inner 
I       side  of  dorsal  surface 
y      of  hand. 
-\   To  wrist  joint. 
'  Palmaris  brevis, 
Integument  of  inner  one 
and  one  half  fingers  on 
palm. 
Muscles  of  little  finger, 
Interossei  muscles, 
The  two  inner  lumbricales, 
Adductor  pollicis. 
Flexor  brevis  pollicis  {in- 
ner head. 


In  the 
forearm. 


In  hand. 


Muscular. 

Palmar  cuta- 
neous. 

Dorsal  cuta- 
neous. 

I  Articular. 

Superficial 
branches. 


Deep 

branches. 


The  accompanying  tables  will  afford  ns  a  better  conception 
of  tlie  distribution  of  the  branches  of  the  three  main  cords  of 
the  brachial  plexus  than  a  long  verbal  description  ;  while  they 
will  also  enable  us,  in  studying  the  practical  points  suggested 
by  the  distribution  of  each  branch,  to  use  the  eye  as  well  as 
the  intelligence  in  following  the  subsequent  lectures.  It  is 
often  impossible  for  one,  not  previously  familiar  with  the 
detail  of  the  nerve  distribution  of  any  part,  to  appreciate  all 
the  deductions  which  may  be  drawn  by  an  author,  without 
much  labor  in  reviewing  the  preceding  text  of  the  work  which 
he  may  be  endeavoring  to  master  ;  and  I  believe  that,  in  f ol- 

'  Modified  from  a  table  in  "  The  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
New  York  :  G.  P.  Putnam's  Sons,  1880. 
45 


670 


THE  SPINAL  NERVES. 


lowing  these  lectures,  these  tables  will  greatly  assist  in  such 
review,  as  well  as  in  affording  you  a  chart  which  can  be  used 
as  a  guide  to  the  preliminary  study  required  in  your  future 
attempts  to  master  other  treatises. 


BRANCHES   OF  THE   POSTERIOR   CORD   OF  THE   BRACHIAL   PLEXUS.' 


Branches  of 

the  POSTE- 
RIOR CORD 

of  the  bra- 
chial plex- 
us. 


(1)  Subscapular 

NERVES. 


(2)  Circumflex. 


(3)  MuscuLO- 

SPIRAL. 


The  upper ^ 

or  1st. 
The  long, 

or  2d. 
The  lower, 

or  3d. 
Superior 
branch. 

Inferior 
branch. 


Muscvlar 
branches. 


Cutaneoits 
branches. 


Radial 

NERVE. 


Subscapular  muscle. 
Latissimus  dorsi. 

Teres  major. 

Deltoid. 

Integument  over  the  back  of  the  shoulder. 

Teres  minor, 

Deltoid  (posterior  portion), 

Integument  over  the  outer  part  of  the 

shoulder. 
Triceps, 
Anconeus, 
Brachialis  anticus, 
Supinator  longus, 
Extensor  carpi  radialis  longior. 
Integumeni  of  the  inner  and  posterior 

portions,  and  the  outer  and  anterior 

portions  of  arm, 
Integument  of  the  outer  aspect  of  the 

forearm. 

( Integumeni  of  outer  side  of 
External  J      thumb, 
branch.  1  Integument  of    ball  of    the 

\^     thumb. 
Internal    i  Integument  of  3|  fingers  on 
branch.  \      radial  side  of  dorsum  of 

(      hand. 
All  muscles  on  back  (  Anconeus, 

of  forearm  except  -<  Supinator  longus, 

three     .     .     .     .  (  Ext.  carp.  rad.  long. 
Filaments  to  the  wrist  joint. 


There  are  still  some  points  pertaining  to  the  individual 
branches  of  the  brachial  plexus  which  can  not  be  shown  in  a 
tabular  arrangement,  but  which  are,  nevertheless,  important, 
as  they  will  enable  you  to  better  understand  the  surgical  and 
medical  aspects  which  are  constantly  brought  to  the  attention 
of  the  active  practitioner.  In  order  to  avoid,  as  far  as  possi- 
ble, any  important  omissions,  and  to  afford  you  a  more  prac- 
tical insight  into  the  uses  to  which  a  knowledge  of  the  nerves 
can  be  applied,  I  will  ask  you  to  follow  me  in  a  review  of  the 


'  Taken,  by  permission  of  the  publishers,  from  "  The  Essentials  of  Anatomy  "  (Dar- 
ling and  Ranney).     New  York :  G.  P.  Putnam's  Sons,  1880. 


THORACIC  AND  MUSGUL0-CUTANE0U8  NERVES.        671 

nerves  of  the  upper  extremity,  using  the  tabulated  charts' 
as  a  means  of  reference,  should  you  become  confused  as  to 
the  source  of  origin  of  the  nerve  under  discussion,  or  fail  to 
grasp  its  subdivisions  and  their  distribution. 

THE  ANTERIOR  THORACIC  NERVES. 

These  two  nerves  are  termed  the  external  and  the  internal, 
since  one  arises  from  the  outer  cord,  and  the  other  from  the 
inner  cord  of  the  brachial  plexus.  The  external  is  sometimes 
also  called  the  superficial,  since  it  crosses  in  front  of  the  ax- 
illary artery  and  vein  to  reach  the  under  surface  of  the  great 
pectoral  muscle  ; "  while  the  internal  is  also  called  the  deep, 
since  it  passes  between  the  same  artery  and  its  accompanying 
vein,  to  be  distributed  to  the  under  surface  of  both  the  great 
and  small  pectoral  muscles.  The  two  nerves  are  connected 
with  each  other  by  a  loop  situated  on  the  inner  side  of  the 
axillary  artery.  It  is  probable  (following  the  axiom  of  Hilton 
as  to  the  cutaneous  distribution  of  nerves)  that  the  skin  over 
the  pectoral  region  receives  filaments  from  these  nerves  as 
well  as  from  the  intercostal  nerves.  As  the  pectoral  muscles 
are  agents  in  effecting  inspiration,  when  any  impediment  ex- 
ists to  breathing,  as  in  asthma,  etc.,  these  nerves  might  be 
classed  as  respiratory  in  function,  although  that  is  not  their 
most  frequent  use. 

THE  EXTERNAL  CUTANEOUS  OR  MUSCULO-CUTANEOUS   NERVE. 

This  nerve  and  its  branches  will  be  found  given  in  the 
table  of  the  subdivisions  of  the  outer  cord'  of  the  brachial 
plexus.  It  passes  through  the  belly  of  the  coraco-brachialis 
muscle  (hence  the  name  "  musculo-cutaneous  " ),  then  between 
the  biceps  and  the  brachialis  anticus  muscles,  to  a  point 
slightly  above  the  external  condyle  of  the  humerus,  where  it 
perforates  the  deep  fascia  and  divides  into  its  cutaneous 

'  See  pages  668,  669,  and  670  of  this  volume. 

^  The  anterior  fibers  of  the  deltoid  muscle  are  said  to  be  supplied  chiefly  by  the  tho- 
racic nerves,  as  revealed  by  clinical  facts. 
'  See  page  668  of  this  volume. 


672 


THE  SPINAL  NERVES. 


brandies  beneath  the  median  cephalic  vein.  Now,  a  reference 
to  the  table  of  its  distribution  will  show  you  that  three  mus- 
cles, which  move  the  arm,  are  supplied  with  motor  power  by 
means  of  this  nerve  ;  hence  we  should  expect  to  find  that  fila- 
ments would  be  sent  to  both  the  shoulder  and  elbow  joints, 
which  these  muscles  move,  and  I  am  inclined  to  think  that 


Fig.  198. — Brachial  portion  of  the  musculo-cutaneous,  median^  and  ulnar  nerves.    (Sappey.) 

1,  musculo-cutaneous  nerve  ;  2,  branch  to  the  coraco-brachialis  muscle  ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  6,  division  of  this  nerve  where  it  crosses  the  apo- 
neurosis of  the  arm  ;  7,  rausculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  internal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch  ;  10,  anterior  or  ulnar  branch  of  this  nerve ;  11,  brachial  por- 
tion of  the  median  and  ulnar  nerves. 


small  filaments  to  the  former  joint  do  actually  exist,  although 
they  are  not  mentioned  in  the  usual  text-books  upon  anatomy. 


jj 


DISTRIBUTION  OF  MU8CUL0-GUTANE0US  NERVE.      673 

We  would  also  expect  that  any  injury '  to  the  trunk  of  this 
nerve  would  be  followed  by  paralysis  or  atrophy  of  these 
three  muscles,  as  well  as  by  a  condition  of  hypersesthesia  or 
anaesthesia  in  the  portions  of  integument  supplied  by  its  ter- 
minal filaments  (the  radial  side  of  the  forearm  and  the  ball  of 
the  thumb) ;  provided  that  the  nerve  be  irritated  or  only 
partly  destroyed,  as  shown  in  the  first  case,  or  entirely  de- 
stroyed, in  which  case  the  latter  condition  should  ensue. 

It  is  a  well-recognized  surgical  fact  that  an  inflamed  condi- 
tion of  the  elbow  joint  tends  to  create  flexion  of  the  forearm, 
by  a  contracted  state  of  the  brachialis  anticus  and  biceps 
muscles  ;  and  the  distribution  of  the  musculo- cutaneous  nerve " 
to  the  joint,  as  well  as  to  these  two  muscles,  enables  us  now 
to  understand  why  the  irritation  of  the  articular  branches  of 
this  nerve  should  manifest  itself  in  a  contracted  state  of  the 
muscles  supplied  by  it. 

The  relation  of  this  nerve  to  the  median-cephalic  vein  will 
also  explain  why  venesection  at  the  elbow  is  liable  to  be  fol- 
lowed by  the  so-called  "bent  arm."  This  fact,  which  has 
been  explained  by  some  authors  as  the  result  of  an  injury 
done  to  the  fascia,  is  much  more  intelligently,  to  my  mind,  at- 
tributed by  Hilton  to  an  injury  done  to  the  filaments  of  the 
musculo-cutaneous  nerve,  resulting  in  a  sympathetic  contrac- 
tion of  the  flexors  of  the  elbow. 

An  exostosis  growing  from  the  humerus,  or  the  existence 
of  a  tumor  in  the  region  of  the  course  of  this  nerve,  might 
cause  a  similar  rigidity  of  the  elbow  joint,  accompanied, 
moreover,  by  a  pain  which  would  follow  the  course  of  the 
nerve  to  its  terminal  filaments.  It  has  been  suggested,  by 
the  author  above  quoted,"  to  apply  anaesthetics  over  the 
course  of  this  nerve  in  order  to  insure  relaxation  of  the 

^  Hilton  reports  a  case  where  an  officer  in  the  navy  presented  a  very  marked  instance 
of  injury  done  to  this  nerve  alone.  It  caused  paralysis  and  atrophy  of  the  three  muscles 
supplied  by  the  musculo-cutaneous  nerve  ;  but  a  perfect  recovery  took  place  in  about  two 
years,  in  spite  of  the  atrophy  which  at  first  existed. 

2  The  ulnar  nerve  also  furnishes  filaments  to  the  elbow  joint  and  supplies  the  flexor 
muscles  of  the  forearm.  This  may  also  tend  to  explain  the  surgical  fact  that  flexion 
follows  inflammation  of  the  elbow. 

^  Hilton,  op.  cit. 


674  THE  SPINAL  NERVES. 

muscles  supplied  by  it  when  the  elbow  is  thus  flexed.  Many 
cases  may  be  cited  from  different  surgical  and  medical  au- 
thors, to  illustrate  the  diagnostic  value  of  this  and  other 
nerves,  in  determining  accurately  the  seat  and  character  of 
disease  which  is  producing  distress  to  the  patient ;  but,  as 
this  aid  to  diagnosis  has  already  been  discussed  at  some 
length  in  previous  lectures,  I  will  simply  mention  it  as  an 
incentive  to  anatomical  study. 

The  cutaneous  distribution  of  this  nerve  will  be  made  clear 
by  referring  to  the  diagram  which  I  now  show  you.'  The 
clinical  value  of  the  cutaneous  nerves  has  already  been  re- 
ferred to  in  previous  lectures."  It  will  therefore  suffice  to 
again  mention,  in  this  connection,  that  hypersesthesia,  local 
pain,  local  points  of  tenderness,  and  anaesthesia  have  often  a 
most  direct  and  positive  bearing  upon  diagnosis  ;  and  the 
axioms  given  in  the  first  lecture  upon  the  spinal  nerves  will 
prove  most  valuable  as  guides  to  the  proper  appreciation  of 
their  significance. 

It  may  strike  some  of  you  who  have  thought  deeply  con- 
cerning the  peculiarities  of  nerve  distribution,  that  this  nerve 
ought  to  stop  at  the  elbow,  since  it  has  supplied  all  of  its 
muscles  before  it  reaches  that  point,  and  has,  therefore,  appar- 
ently performed  its  function  ;  and  this  feeling  will  possibly 
be  strengthened  by  the  axiom  given  you  in  a  previous  lec- 
ture," viz.,  that  a  nerve  is  always  associated  with  that  portion 
of  the  integument  which  covers  Wiq  points  of  insertion  of  the 
muscles  to  which  it  furnishes  motor  power.  If  you  will  ex- 
amine closely,  however,  into  the  insertion  of  the  biceps  mus- 
cle, you  will  observe  that  it  is  intimately  connected  with  the 
fascia  of  the  forearm — so  intimately  that  this  fascia  is,  in  re- 
ality, an  inherent  part  of  the  insertion  of  that  muscle.  This, 
then,  confirms  not  only  the  truth  of  the  general  axiom  given 
by  Hilton,*  but  also  explains  to  the  inquiring  mind  why  this 
nerve  should  be  continued  downward  to  the  wrist,  since  it  has 
to  do  so  in  order  to  cover  the  skin  over  one  of  the  most  impor- 


*  See  page  682  of  this  volume.  '  See  pages  645  and  646  of  this  volume, 

•  See  page  646  of  this  volume.  *  Op.  cit. 


1 


DISTRIBUTION  OF  MU8CUL0-CUTANE0US  NERVE.      675 

tant  points  of  insertion  of  a  muscle  wMch  it  controls.     Other 
facts  in  the  anatomy  of  the  forearm  seem  to  still  more  beauti- 


FiG.  199. — Cutaneous  nerves  of  the  antei'ior  surface  of  the  forearm  and  hand.    (Hirsch 

feld.) 

9,  epi-trochlear  branch  from  the  musculo-spiral  nerve  anastomosing  by  a  division  with 
the  anterior  branch  of  the  same  nerve  ;  10,  10,  anterior  brancli  of  the  internal  cuta- 
neous of  the  arm  dividing  into  several  branches,  some  of  which  pass  in  front  of 
and  others  behind  the  median  basilic  vein;  11,  11,  musculo-cutaneous  nerve  crossing 
the  aponeurosis  of  the  arm  outside  of  the  tendon  of  the  biceps  muscle;  12,  12,  di- 
visions of  the  external  cutaneous  branch  of  the  radial  distributing  themselves  to  the 
skin  of  the  posterior  portion  of  the  forearm ;  13,  18,  13,  divisions  which  the  anterior 
branch  of  the  internal  cutaneous  furnishes  to  the  forearm ;  14,  anastomosis  of  one 
of  these  divisions  with  a  perforating  branch  of  the  ulnar  nerve;  15,  15,  15,  termi- 
nal divisions  of  the  musculo-cutaneous  nerve;  16,  anastomosis  of  one  of  these 
divisions  with  17,  the  terminal  anterior  branch  of  the  radial  nerve;  18,  palmar 
cutaneous  branch  of  the  median  ;  19,  internal  branch  of  distribution  to  the  thumb; 
20,  external  branch  of  distribution  to  the  same ;  21,  external  branch  of  distri- 
bution to  the  index  finger;  22,  trunk  of  the  branches  of  distribution  to  the  in- 
ternal side  of  the  index  and  external  aspect  of  middle  fingers ;  23,  common  trunk 
of  distribution  to  the  internal  side  of  the  middle  and  external  side  of  the  ring 
fingers ;  24,  trunk  of  distribution  to  the  internal  side  of  the  ring  and  external  side 
of  the  little  finger;  25,  branch  of  distribution  to  the  internal  side  of  the  little 
finger. 


676  THE  SPINAL  NERVES. 

fully  confirm  this  same  general  law.  We  see  the  musculo- 
spiral  nerve  sending  a  filament  to  nearly  the  same  region  as 
the  musculo-cutaneous,  because  it  supplies  the  supinator  lon- 
gus,  which  is  situated  upon  the  outer  side  of  the  forearm ; 
while,  again,  the  internal  cutaneous  nerve  (which  properly 
may  be  considered  as  a  branch  of  the  median,  since  it  arises 
by  a  common  head)  supplies  the  skin  of  the  inner  side  of  the 
anterior  surface  of  the  forearm,  for  the  evident  reason  that 
the  muscles  supplied  by  the  median  are  extensively  attached 
to  this  same  fascia. 

CLINICAL    POINTS    PERTAINING    TO    THE    MUSCULO-CUTANEOUS 

NERVE. 

A  paralysis  limited  to  this  nerve  is  an  unusual  occurrence. 
It  may  be  produced,  however,  by  any  form  of  injury  or  of 
local  pressure  which  alone  involves  this  nerve  trunk,  and  it 
must  be  situated  in  the  region  of  the  coraco-brachialis  muscle 
to  create  impairment  of  all  of  its  filaments  of  distribution. 
Complete  paralysis  of  this  nerve  causes  total  paralysis  of  the 
biceps  and  coraco-brachialis  muscles,  but  only  a  partial  loss 
of  power  in  the  brachialis  anticus,  since  that  muscle  is  also 
furnished  with  a  filament  derived  from  the  musculo-spiral 
nerve.  The  skin  of  the  outer  border  of  the  forearm  is  also 
rendered  ansesthetic  when  this  nerve  is  injured.  As  a  result 
of  paralysis  of  the  muscles  named,  the  power  to  flex  the  fore- 
arm upon  the  arm  is  greatly  impaired,  and  would  be  totally 
lost  if  the  supinator  longus  and  a  part  of  the  brachialis  anti- 
cus muscles  were  not  capable  of  assisting  that  movement. 
These  latter  muscles,  being  supplied  by  the  musculo-spiral 
nerve,  still  retain  their  power  of  contraction  ;  hence  the  diffi- 
culty in  performing  flexion  of  the  forearm  is  greater  when 
the  hand  is  supinated,  as  the  supinator  longus  no  longer  acts 
to  any  great  extent  as  a  flexor. '  The  seat  of  the  anaesthesia 
is  a  valuable  guide  to  the  nerve  affected,  as  the  musculo-cuta- 

^  The  supinator  muscle  is  an  important  aid  in  flexion  of  the  forearm,  when  the  hand 
is  pronatcd :  but  it  is  of  little  value  as  a  flexor  after  the  function  of  supination  has  been 
performed  by  it. 


TEE  MEDIAN  NERVE. 


677 


neous  nerve  may  possibly  be  involved,  without  any  impair- 
ment of  the  other  branches  of  the  outer  cord  of  the  brachial 
plexus. 


Fig.  200. — Cutaneous  nerves  of  the  shovlder  and  posterior  surface  of  the  arm.     (Sappey.) 

1,  1,  terminal  ramifications  of  the  supra-acromial  branch  of  the  cervical  plexus;  2,  cuta- 
neous branch  of  the  circumflex  nerve ;  3,  another  cutaneous  branch  of  the  same 
nerve  traversing  the  posterior  border  of  the  deltoid ;  4,  terminal  divisions  of  the 
perforating  branch  of  the  second  intercostal  nerve ;  5,  perforating  branch  of  the 
third  intercostal  nerve ;  6,  internal  cutaneous  branch  of  the  musculo-spiral  nerve ; 
7,  epitrochlear  branch  of  the  internal  cutaneous  nerve ;  8,  posterior  division  of  the 
ulnar  branch  of  the  internal  cutaneous ;  9,  external  cutaneous  division  of  the  radial 
nerve ;  10,  10,  internal  cutaneous  filament  of  the  radial  nei-ve. 


THE   MEDIAN   I^ERVE. 

While  this  nerve  arises  by  two  heads,  derived,  respectively, 
from  the  outer  and  inner  cords  of  the  brachial  plexus,  it  has 
been  classed  as  a  branch  of  the  former.'    This  nerve  bears  a 

'  The  reader  is  referred  to  the  table  on  page  664  of  this  volume. 


678 


THE  SPINAL  NERVES, 


Fig.  201. — Cutaneou,s  nerves  of  the  posterior  surface  of  ilie  forearm  aiid  hand.    (Sappey.) 

7,  epi-trochlear  branch  of  the  internal  cutaneous  nerve ;  8,  posterior  division  of  the  ulnar 
branch  of  the  internal  cutaneous ;  9,  external  cutaneous  division  of  the  radial  nerve ; 
10,  10,  internal  cutaneous  lilament  of  the  radial  nerve;  11,  posterior  division  of  the 
anterior  terminal  or  cutaneous  branch  of  the  radial  nerve  ;  12,  first  twig  rising  from 
this  branch  (it  forms  the  external  dorsal  nerve  of  distribution  to  the  thumbs) ;  13,  sec- 
ond twig  of  the  same  division  (it  subdivides  at  the  superior  part  of  the  first  intercostal 
space — one  of  these  divisions  forms  the  internal  dorsal  cutaneous  nerve  of  the  thumb, 
the  other  ramifies  in  the  skin  of  the  dorsal  face  of  the  first  phalanx  of  the  index 
finger) ;  14,  third  branch,  which  descends  into  the  second  interosseous  space,  where 
it  bifurcates  (one  of  these  divisions  is  lost  in  the  internal  half  of  the  integument  on 
the  dorsal  surface  of  the  first  phalanx  of  the  index  finger,  and  the  other  in  the  exter- 
nal half  of  the  skin  which  covers  the  dorsal  surface  of  the  middle  finger) ;  15,  dorsal 
branch  of  the  ulnar  nerve;  16,  external  division  of  this  branch  anastomosing  with 
one  or  two  filaments  of  the  anterior  terminal  branch  of  the  radial  passing  directly 
into  the  third  interosseous  space,  where  it  divides  (one  of  these  divisions  ramifies  in  the 
internal  half  of  the  skin  which  invests  the  first  phalanx  of  the  middle  finger,  the  other 
supplies  the  first  phalanx  of  the  ring  finger) ;  17,  second  ramification  of  the  same 
branch,  which  also  bifurcates  under  the  fourth  interosseous  space  (one  of  these 
divisions  ramifies  in  the  skin  on  the  dorsal  surface  of  the  first  phalanx  of  the  ring 
finger,  the  other  forms  the  external  dorsal  nerve  of  distribution  to  the  little  finger) ; 
18,  internal  dorsal  nerve  of  distribution  to  the  little  finger. 


DISTRIBUTION  OF  THE  MEDIAN  NERVE.  679 

surgical  relation  to  the  brachial  artery,  since  it  lies,  at  first, 
upon  the  outer  side  of  that  vessel,  then  crosses  it,  and,  finally, 
reaches  its  inner  side  at  the  bend  of  the  elbow.  It  enters  the 
forearm  between  the  two  heads  of  the  pronator  radii  teres 
muscle,  passes  down  the  middle  line  of  the  anterior  surface  of 
the  forearm  till  it  reaches  the  annular  ligament  of  the  wrist, 
then  passes  underneath  the  arch  formed  by  that  ligament, 
when  it  becomes  flattened  and  expanded  in  front  of  the  flexor 
tendons  in  the  palm  of  the  hand,  and  finally  terminates  in 
branches  to  the  muscles  and  integument  of  the  hand  and 
fingers.  The  table,  which  has  been  referred  to  in  previous 
lectures,*  will  show,  more  plainly  than  a  tedious  verbal  de- 
scription, the  parts  supplied  by  this  nerve  in  the  different  por- 
tions of  its  course.  This  nerve,  in  connection  with  its  fellow, 
the  ulnar  nerve,  furnishes  motor  power  to  all  the  flexor  and 
pronator  muscles  of  the  forearm,  and  all  the  muscles  of  the 
palm  of  the  hand  ;  the  median  supplying  all  the  muscles  on 
the  anterior  surface  of  the  forearm  but  one  and  a  half  (the 
flexor  carpi  ulnaris,  and  one  half  of  the  flexor  profundus  digi- 
torum),  and  four  and  a  half  muscles  on  the  radial  side  of  the 
palm  (as  shown  by  the  table).  Now,  as  the  ulnar  nerve  sup- 
plies all  the  rest  of  the  muscles  of  the  anterior  surface  of  the 
forearm  and  hand,  these  two  nerves  may  be  considered  as  the 
flexor  and  pronator  nerves  of  those  regions. '^ 

The  cutaneous  distribution  of  the  median  nerve  is  of  in- 
terest, since  it  confirms  the  axiom '  of  nerve  distribution  to  the 
integument  over  the  muscles.  We  find  that  the  median  sends 
no  cutaneous  filaments  to  the  dorsal  surface  of  the  thumb,  but 
that  it  does  supply  its  palmar  surface  ;  the  dorsal  surface  is 
covered  with  the  extensor  tendons,  which  owe  their  motor  pow- 
er to  the  posterior  interosseous  branch,  and  the  skin  is  there- 
fore supplied  from  the  same  source.  The  sides  of  the  outer  two 
and  a  half  fingers  (those  adjoining  the  thumb)  are  likewise 

^  See  page  668  of  this  volume. 

'  In  speaking  of  the  combined  action  of  the  median  and  ulnar  nerves,  Hilton  says : 
"  These  nerves,  together,  supply  all  the  flexors  of  the  wrist  joint,  fingers  and  thumb,  all 
the  pronators  of  the  radio-ulnar  joints,  and  all  the  joints  that  these  muscles  move." 

8  See  page  643  of  this  volume. 


680 


THE  SPINAL  NERVES. 


Fig.  202. — Brachial  portion  of  the  musculo-  FiG.  203.  —  Terminal  portion  of  the  median 
cutaneous,  median,  and  ulnar  nerves.  and  ulnar  nerves.     (Sappey.) 

(Sappey.) 

1,  musculo- cutaneous  nerve ;  2,  branch  to  the  coraco-brachialis  muscle ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  6,  division  of  this  nerve  where  it  crosses  the  apo- 
neurosis of  the  arm ;  1,  musculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  internal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch;  10,  anterior  or  ulnar  branch  of  this  nerve ;  11,  brachial 
portion  of  the  median  and  ulnar  nerves ;  12,  antebrachial  portion,  palmar  and  digital 
branches  of  the  same  nerve;  13,  branch  to  the  pronator  radii  teres;  14,  trunk  of 
these  anterior  muscular  branches  dividing  and  passing  to  the  muscles  to  which  they 
are  distributed;  15,  branch  to  the  flexor  profundus  digitorum;  16,  branch  to  the 
flexor  longus  pollicis  ;  1 7,  anterior  interosseous  branch  ;  1 8,  palmar  cutaneous  branch 
dividing  just  below  its  origin;  19,  muscular  branch  of  the  thenar  eminence;  20,  ex- 
ternal branch  of  distribution  to  the  thumb  ;  21,  internal  branch  of  distribution  to  the 
same ;  22,  external  branch  of  distribution  of  the  index  finger ;  23,  common  trunk  of 
the  internal  branches  of  distribution  to  the  index  finger  and  external  to  the  middle 
finger  ;  24,  internal  trunk  of  distribution  to  the  middle  and  external  branch  to  the 
ring  finger ;  25,  branch  which  the  ulnar  nerve  furnishes  to  the  flexor  carpi  ulnaris ; 
26,  branches  which  the  same  nerve  furnishes  to  the  two  internal  fasciculi  of  the 
flexor  profundus  digitorum;  27,  cutaneous  and  anastomotic  filament  of  the  ulnar 
nerve ;  28,  dorsal  branch  of  this  nerve  ;  29,  its  superficial  palmar  branch  ;  30,  com- 
mon trunk  of  the  internal  branch  of  distribution  to  the  ring  and  external  branch  to 


CLINICAL  POINTS  AFFORDED  BY  MEDIAN  NERVE,     681 

the  little  finger ;  31,  internal  branch  of  distribution  to  the  little  finger ;  32,  deep 
palmar  branch ;  33,  small  branch  to  the  hypo-thenar  eminence ;  34,  branches  to  the 
muscles  of  the  fourth  interosseous  space  and  the  fourth  lumbricalis  muscle;  35, 
branches  to  the  muscles  of  the  third  interosseous  space  and  the  third  lumbricalis 
muscle ;  36,  branches  to  the  adductor  pollicis  and  muscles  of  the  first  and  second 
interosseous  spaces. 

supplied  with  integumentary  branches  from  the  median,  the 
balance  being  supplied  by  similar  branches  of  the  ulnar  nerve. 
The  two  outer  lumbricales  muscles  are  enumerated  in  the 
preceding  tables,  as  supplied  by  the  median,  and  the  remain- 
ing lumbricales  and  interossei  muscles  by  the  ulnar  nerve. 
Now,  the  method  of  insertion  of  the  tendons  of  these  muscles 
(into  the  extensor  tendon  of  the  corresponding  finger,  on  its 
dorsal  surface)  causes  these  muscles  to  flex  the  proximal 
phalanx^  and  extend  the  two  remaining  phalanges '  of  each 
finger.  We  find,  therefore,  that  the  nerve  branches,  which 
supply  these  muscles,  send  cutaneous  filaments  to  the  dor- 
sal surface  of  the  two  terminal  phalanges  of  the  finger  upon 
which  the  individual  muscles  act,  thus  apparently  confirming 
the  extensor  action  of  the  muscles,  since  the  distribution  of 
nerves,  derived  apparently  from  a  flexor  source,  comprises  a 
region  covered  by  the  extensor  tendons  of  the  fingers. 

CLINICAL   POINTS   PERTAINING   TO    THE   MEDIAN   NERVE. 

The  median  nerve  is  rarely  affected  with  paralysis,  to  the 
exclusion  of  other  nerves.  If  such  a  condition  exists,  it  may 
probably  be  traced  to  some  local  injury,  such  as  cuts,  frac- 
tures of  the  humerus,  the  use  of  badly  constructed  crutches, 
contusions  over  the  course  of  the  nerve,  gunshot  wounds,  un- 
skillful venesection,  local  pressure  from  tumors,  abscess,  etc. 
It  may  possibly  be  due  to  rheumatism,  neuritis,"  neuromata, 
and  central  causes.  The  muscles  of  the  ball  of  the  thumb, 
which  are  supplied  by  this  nerve,  are  frequently  the  seat 

*  Hunter,  Cleland,  Duchenne,  Erb,  and  others  consider  the  interossei  muscles  alone  as 
extensors  of  the  two  terminal  rows  of  phalanges.  Clinical  facts  observed  in  lead  paraly- 
sis and  in  division  of  the  ulnar  nerve  seem  to  point  to  these  muscles  rather  than  to  the 
lumbricales,  although  Hilton  groups  the  lumbricales  and  interossei  muscles  as  possessing 
a  common  function. 

^  This  condition  may  follow  any  acute  disease.  It  is  one  of  the  sequelae  of  typhoid 
fever. 


682 


THE  SPINAL  NERVES. 


of  a  progressive  muscular  atrophy  and  its  consequent  paral- 
ysis. 

From  what  has  already  been  said  respecting  the  distribu- 


FiG.  204. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  in  the  anteiHor  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

1,  region  supplied  by  the  supra-clavicular  nerve  (branch  of  the  cervical  plexus);  2,  re- 
gion supplied  by  the  circumflex  nerve  ;  3,  region  supplied  by  the  intcrcosto-humeral 
nerve;  4,  region  supplied  by  the  intercostal  nerve  (lateral  branch) ;  5,  region  sup- 
plied by  the  lesser  internal  cutaneous  nerve  (nerve  of  Wrisberg) ;  6,  region  supplied 
by  the  musculo-spiral  nerve  (external  cutaneous  branch) ;  7,  region  supplied  by  the 
internal  cutaneous  nerve ;  8,  region  supplied  by  the  musculo-cutaneous  nerve ;  9, 
region  supplied  by  the  median  nerve  ;  10,  region  supplied  by  the  ulnar  nerve ;  11, 
region  supplied  by  the  intercostal  nerve  (anterior  branch). 

tion  of  this  nerve,  we  are  prepared  to  understand  why  the 
common  flexors  of  the  fingers  and  those  of  the  wrist  should 


PARALYSIS  OF  THE  MEDIAN  NERVE.  683 

show  a  loss  of  power,  in  case  the  median  be  injured,  and  the 
muscles  of  the  thumb  give  evidence  of  the  diseased  condition. 
You  will  find,  in  such  cases,  that  the  second  phalanges  of  all 
the  fingers  and  the  third  phalanges  of  the  index  and  middle ' 
fingers  can  not  be  flexed,  and  that  the  thumb  can  not  be 
flexed  or  brought  into  contact  with  the  little  finger.  On  the 
other  hand,  flexion  of  the  first  phalanx,  with  extension  of  the 
other  two,  can  be  performed  in  all  the  fingers  by  the  aid  of 
the  interossei  which  are  supplied  by  the  ulnar  nerve.  The 
position  of  the  thumb  is  peculiar ;  it  is  extended  and  ad- 
ducted  and  thus  closely  applied  to  the  index  finger,  as  in  the 
hand  of  the  ape.  The  hand,  when  flexion  at  the  wrist  is 
attempted,  is  strongly  adducted  by  the  action  of  the  flexor 
carpi  ulnaris,  as  the  antagonistic  muscle  of  the  radial  side  is 
paralyzed.  The  act  of  pronation  of  the  hand  is  seriously  im- 
paired. The  inner  three  fingers  can  be  brought  into  a  par- 
tially flexed  condition,  since  the  flexor  profundus  digitorum 
muscle  is  partly  supplied  by  the  ulnar  nerve.  These  com- 
bined effects  give  to  the  hand  and  fingers,  and  especially  to 
the  thumb,  a  position  so  peculiar  that  paralysis  of  the  median 
could  hardly  be  mistaken  by  an  anatomist  for  any  other  de- 
formity. When  the  paralyzed  muscles  begin  to  show  the 
results  of  atrophy,  the  deformity  in  the  forearm  and  in  the 
ball  of  the  thumb  will  further  assist  in  the  diagnosis  of  this 
affection. 

The  anastomosis  which  exists  between  the  cutaneous  nerves 
of  the  forearm  will  possibly  tend  to  explain  the  fact  that  com- 
plete destruction  of  the  median,  ulnar,  or  radial  nerves  may 
exist  without  any  marked  loss  of  sensibility  in  the  regions 
supplied  by  the  affected  nerve.  Should  any  such  evidences 
of  disordered  sensibility  be  present,  however,  it  will  be  con- 
fined to  the  region  supplied  by  the  nerve  which  is  the  seat  of 
disease,  or  whose  conducting  power  has  been  impaired  from 
any  cause.  If  the  median,  ulnar,  or  radial  nerves  be  injured 
below  the  wrist,  the  absence  of  anastomosis  tends  to  make  the 

*  The  flexor  sublimis  digitorum  being  completely  paralyzed,  and  the  flexor  profundus 
digitorum  being  partially  deprived  of  its  motor  power. 


084  THE  SPINAL  NERVES. 

symptom  of  ansestliesia  a  constant  and  important  guide  to  tlie 
nerve  affected. 

In  severe  paralysis  of  the  median  nerve,  the  first  three 
fingers '  not  infrequently  show  trophic  disturbances  in  the 
skin  and  nails,  such  as  glossy  fingers,  ulceration,  pemphigus 
vesicles,  abnormal  growth  of  hair,  etc. 

The  relation  of  the  median  nerve  to  the  brachial  artery 
gives  to  it  a  surgical  importance.     It  wiU  be  observed  that   \ 
the  nerve  lies,  at  first,  to  the  outer  side  of  that  vessel ;  later   \ 
on,  it  crosses  it,  and  finally  passes  to  the  inner  side  of  the   j 
artery  in  the  region  of  the  elbow.  i 

THE   INTERNAL  CUTANEOUS   AND   LESSER  INTERNAL  CUTANEOUS         \ 

NERVES.  j 

These  two  nerves  arise  from  the  inner  cord  of  the  brachial  j 
plexus,  in  common  with  the  inner  head  of  the  median  and  the 

ulnar  nerves.  ; 

The  internal  cutaneous  nerve  accompanies  the  brachial 
artery,  lying  upon  its  inner  side  and  in  front  of  the  lesser  in- 
ternal cutaneous  nerve,  till  the  basilic  vein  pierces  the  deep  ; 
fascia,  when  the  nerve  accompanies  the  vein  and  soon  divides 
into  an  anterior  and  posterior  branch,   whose  distribution  \ 
will  be  found  given  in  preceding  tables.    It  assists  the  coraco-  j 
humeral  nerve  in  supplying  the  integument  over  the  biceps  J 
muscle,  and  sends  filaments  to  the  skin  of  the  forearm  as  low  'I 
down  as  the  wrist.'  j 

The  lesser  internal  cutaneous  nerve,  called  also  the  nerve  of  ' 

Wrisberg,"  has  the  same  general  origin  as  the  preceding  nerve,  ; 

except  that  it  arises  slightly  below  it.    Like  the  former  nerve,  j 
it  accompanies  the  brachial  artery,  lying  upon  its  inner  side 

and  behind  the  nerve  just  described,  and,  after  its  escape  ^ 

from  the  fascia,  it  supplies  the  skin  of  the  lower  third  of  the  ^ 

arm,*  becoming  joined  to  the  posterior  branch  of  the  internal  ^| 

*  Those  adjoining  the  thumb.     See  figure  on  page  682  of  this  volume. 

*  See  cut  on  page  682  of  this  volume. 

*  For  the  region  of  cutaneous  distribution  to  this  nerve,  the  reader  is  referred  to  the 
diagrammatic  cuts  on  pages  675  and  682  of  this  volume. 

*  See  Fig.  204  of  this  volume. 


^i 


THE   ULNAR  NERVE. 


685 


Fig.  205. —  Cutaneous  nerves  of  the  shouU      Fig.  206. —  Cutaneous  nerves  of  the  ante- 
der  and  anterior  surface  of  the  arm.  rior  surface  of  the  forearm  and  hand, 

(Hirschfeld.)  (Hirschfeld.) 

1, 1,  divisions  of  the  supra-acromial  branch  of  the  cervical  plexus  ;  2,  2,  2,  terminal  rami- 
fications of  the  cutaneous  division  of  the  circumflex  nerve  ;  3,  division  of  the  inter- 
nal cutaneous  nerve  of  the  arm ;  4,  small  filament  from  the  perforating  branch  of 
the  second  intercostal  nerve ;  5,  external  cutaneous  branch  from  the  musculo-spiral 
nerve  ;  6,  internal  cutaneous  branch  crossing  the  aponeurosis  of  the  arm ;  1,  epi- 
trochlear  branch  of  this  nerve,  anastomosing  by  a  division  with  8,  the  ulnar  nerve, 
and  9,  9,  with  the  anterior  branch  of  the  same  nerve ;  10,  10,  anterior  branch  of  the 
internal  cutaneous  df  the  arm,  dividing  into  several  branches,  some  of  which  pass  in 
front  of  and  others  behind  the  median-basilic  vein  ;  11,  11,  musculo-cutaneous  nerve 
crossing  the  aponeurosis  of  the  arm  outside  of  the  tendon  of  the  biceps  muscle  ;  12, 
12,  divisions  of  the  external  cutaneous  branch  of  the  radial,  distributing  themselves 
to  the  skin  of  the  posterior  portion  of  the  forearm  ;  13,  13,  13,  divisions  which  the 
anterior  branch  of  the  internal  cutaneous  furnishes  to  the  forearm  ;  14,  anastomosis 
of  one  of  these  divisions  with  a  perforating  branch  of  the  ulnar  nerve  ;  15,  15,  15, 
tei^minal  divisions  of  the  musculo-cutaneous  nerve  ;  16,  anastomosis  of  one  of  these 
divisions  with  1 7,  the  terminal  anterior  branch  of  the  radial  nerve  ;  1 8,  palmar  cuta- 
neous branch  of  the  median  ;  19,  internal  branch  of  distribution  to  the  thumb  ;  20, 
external  branch  of  distribution  to  the  same  ;  21,  external  branch  of  distribution  to 
the  index. finger ;  22,  trunk  of  the  branches  of  distribution  to  the  internal  side  of  the 
index  and  external  aspect  of  middle  fingers  ;  23,  common  trunk  of  distribution  to  the 
internal  side  of  the  middle  and  external  side  of  the  ring  fingers  ;  24,  trunk  of  distri- 
bution to  the  internal  side  of  the  ring  and  external  side  of  the  little  finger  ;  25, 
branch  of  distribution  to  the  internal  side  of  the  little  finger. 
46 


686  THE  SPINAL  NERVES. 

cutaneous  nerve  or  to  the  intercosto-humeral  nerve.  The  size 
of  this  nerve  varies,  as  it  is  often^  supplanted  by  the  intercos- 
to-humeral '  nerve,  which  is  then  of  extremely  large  size.  In 
this  case  the  nerve  of  Wrisberg  may  be  entirely  w^anting, 
and  the  intercosto-humeral  nerve  act  independently  of  any 
communication  with  the  brachial  plexus. 

THE   ULNAR   NERVE. 

This  nerve  arises  from  the  inner  cord  of  the  brachial  plex- 
us, in  common  with  the  internal  cutaneous  and  the  nerve  of 
Wrisberg,  as  well  as  with  the  inner  head  of  the  median  nerve. 
It  bears  a  surgical  relation  with  the  third  portion  of  the  ax- 
illary artery  and  the  upper  part  of  the  brachial  artery,  since 
it  lies  internally  to  and  in  close  proximity  with  both  ;  but  it 
gradually  separates  from  the  brachial  artery  as  it  passes  down 
the  arm.  It  perforates  the  deep  fascia  of  the  arm  in  company 
with  the  inferior  profunda  branch  of  the  brachial  artery,  and 
descends  in  a  groove  between  the  olecranon  process  of  the 
ulna  and  the  inner  condyle  of  the  humerus,  until  it  enters  the 
forearm  by  passing  between  the  two  heads  of  the  flexor  carpi 
ulnaris  muscle.  In  the  forearm,  this  nerve  bears  a  relation 
with  the  ulnar  artery,  especially  in  the  middle  and  lower 
thirds  of  that  region  ;  the  artery  lying  upon  the  outer  side  of 
the  nerve.  At  the  wrist,  this  nerve  winds  around  the  outer 
side  of  the  pisiform  bone,  crosses  the  annular  ligament,  and 
divides  into  its  two  terminal  branches.  The  tabulated  ar- 
rangement of  the  branches  of  distribution  of  the  ulnar  nerve ' 
will  show  the  muscles  supplied  by  it,  both  in  the  forearm  and 
hand.  It  is  important  to  remember  that  thi^  nerve  gives  fila- 
ments to  both  the  elbow  and  wrist  joints,  and  that  its  cutane- 
ous branches  are  confined  to  the  fingers  and  palm  of  the 
hand. 

By  a  glance  at  the  diagrammatic  representation  of  the 
regions  of  the  integument  of  the  upper  extremity,  supplied 
by  individual  nerves  (see  Figs.  204  and  212),  you  will  per- 
ceive that  the  ulnar  nerve  supplies  the  dorsal  and  palmar 

*  A  branch  of  the  second  intercostal  nerve.  '  See  page  669  of  this  volume. 


DISTRIBUTION  OF  THE   ULNAR  NERVE. 


687 


Fig.  207. — Brachial  portion  of  the  musculo-  Fig.  208.  —  Terminal  portion  of  the  median 
cutaneous^  median,  and  ulnar  nerves,  and  ulnar  nerves.     (Sappey.) 

(Sappey.) 

1,  musculo-cutaneous  nerve ;  2,  branch  to  the  coraco-brachialis  muscle  ;  3,  branch  to  the 
biceps  muscle ;  4,  branch  to  the  brachialis  anticus ;  5,  anastomotic  filament  which  it 
receives  from  the  median  nerve ;  6,  division  of  this  nerve  where  it  crosses  the  apo. 
neurosis  of  the  arm ;  7,  musculo-spiral  nerve  passing  between  the  brachialis  anticus 
and  supinator  longus  muscles ;  8,  external  cutaneous  branch  of  the  musculo-spiral 
nerve  ;  9,  trunk  of  the  internal  cutaneous  dividing  just  below  its  origin,  thus  giving 
off  an  accessory  branch;  10,  anterior  or  ulnar  branch  of  this  nerve  ;  11,  brachial 
portion  of  the  median  and  ulnar  nerves ;  12,  antebrachial  portion,  palmar  and  digital 
branches  of  the  same  nerve;  13,  branch  to  the  pronator  radii  teres;  14,  trunk  of 
these  anterior  muscular  branches  dividing  and  passing  to  the  muscles  to  which  they 
are  distributed;  15,  branch  to  the  flexor  profundus  digitorum;  16,  branch  to  the 
flexor  longus  pollicis ;  1 7,  anterior  interosseous  branch  ;  1 8,  palmar  cutaneous  branch 
dividing  Just  below  its  origin;  19,  muscular  branch  of  the  thenar  eminence;  20,  ex- 
ternal branch  of  distribution  to  the  thumb ;  21,  internal  branch  of  distribution  to  the 
same;  22,  external  branch  of  distribution  of  the  index  finger;  23,  common  trunk  of 
the  internal  branches  of  distribution  to  the  index  finger  and  external  to  the  middle 
finger ;  24,  internal  trunk  of  distribution  to  the  middle  and  external  branch  to  the 
ring  finger ;  25,  branch  which  the  ulnar  nerve  furnishes  to  the  flexor  carpi  ulnaris ; 
26,  branches  which  the  same  nerve  furnishes  to  the  two  internal  fasciculi  of  the 
flexor  profundus  digitorum ;  27,  cutaneous  and  anastomotic  filament  of  the  ulnar 
nerve;  28,  dorsal  branch  of  this  nerve  ;  29,  its  superficial  palmar  bi\anch';  30,  com- 
mon trunk  of  the  internal  branch  of  distribution  to  the  ring  and  external  branch  to 


^88  THE  SPINAL  NERVES. 

the  little  finger;  SI;  internal  branch  of  distribution  to  the  little  finger;  32,  deep 
palmar  branch ;  33,  small  branch  to  the  hypo-thenar  eminence  ;  34,  branches  to  the 
muscles  of  the  fourth  interosseous  space  and  the  fourth  lumbricalis  muscle ;  35, 
branches  to  the  muscles  of  the  third  interosseous  space  and  the  third  lumbricalis 
muscle ;  36,  branches  to  the  adductor  poUicis  and  muscles  of  the  first  and  second 
interosseous  spaces. 

surfaces  of  the  inner  one  and  a  half  fingers^  thus  leaving 
three  and  a  half  fingers  upon  the  palm  for  the  median  nerve, 
and  three  and  a  half  fingers  on  the  back  of  the  hand  for  the 
radial  nerve  to  supply.  Thus  the  integument  of  the  palm  is 
as  equally  divided  between  these  three  nerves  as  could  well 
be,  as  the  ulnar  has  a  total  of  three  fingers  (one  and  a  half 
on  both  the  palm  and  back  of  hand),  and  the  other  two 
nerves  three  and  a  half  fingers  each. 

CLINICAL   POINTS   OF   INTEREST   PERTAINING   TO   THE   ULNAR   NERVE. 

The  superficial  situation  of  this  nerve  in  the  arm,  near  the 
elbow  and  at  the  wrist,  would  seem  to  suggest  that  paralysis 
of  this  nerve  would  be  a  ^latter  of  common  occurrence,  as  it 
is  apparently  exposed  to  injury.  It  is,  nevertheless,  infre- 
quently affected  with  traumatic  paralysis.  The  causes  which 
reported  cases  show  to  have  produced  this  condition  include 
about  the  same  list  of  accidents  as  mentioned  in  connection 
with  paralysis  of  the  median  nerve ;  but  sleeping  upon  the  arm 
when  placed  beneath  the  head,  the  use  of  poorly  constructed 
crutches,  fractures  and  dislocations  at  the  shoulder,  tumors, 
contusions,  wounds  of  all  kinds,  neuritis,'  and  neuromata  are 
among  the  most  common.  Resting  upon  the  elbow  has  been 
reported  by  Duchenne  as  a  cause  of  this  type  of  paralysis  in 
a  certain  class  of  workmen;  and  the  so-called  ''injury  to  the 
funny  bone,"  which  consists  of  a  contusion  over  the  seat  of 
the  ulnar  nerve  at  the  elbow,  seems  to  justify  the  conclusion 
that  this  might  easily  be  the  seat  of  paralysis  from  long-con- 
tinued or  constant  pressure. 

It  is  a  rule  among  surgeons,  when  operating  about  the 
elbow  joint,*  to  guard  against  injury  to  the  ulnar  nerve,  espe- 

*  Rosenthal  states  that  this  condition  is  most  frequent  after  typhoid  fever  and  acute 
diseases. 

'  This  is  especially  important  in  excision  of  this  joint,  as  the  nerve  is  apt  to  be  injured 
in  raising  the  periosteum  from  the  bone. 


CLINICAL  POINTS  AFFORDED  BY  ULNAR  NERVE.      689 

cially  when  the  steps  of  the  operation  bring  the  knife  in 
proximity  to  the  inner  condyle  of  the  humerus. 

As  has  been  mentioned  in  connection  with  the  median  nerve, 
the  ulnar,  as  well  as  the  median  nerve,  may  be  considered  as 
a  pronator  and  flexor  nerve  of  the  wrist  and  a  flexor  nerve 
of  the  fingers,  since  the  distribution  of  the  two  is  confined 
exclusively  to  the  anterior  surface  of  the  forearm  and  the 
palmar  surface  of  the  hand.  The  table  of  the  branches  of  the 
ulnar  nerve '  will  help  us  to  readily  appreciate  the  peculiari- 
ties of  ulnar  paralysis  from  a  theoretical  standpoint,  and  to 
properly  interpret  the  phenomena  when  met  in  actual  expe- 
rience. 

We  can  see,  by  reference  to  the  table,  that  the  flexor  carpi 
ulnaris  and  the  greater  part  of  the  flexor  profundus  digito- 
rum  muscles  w^ould  be  paralyzed,  and  that  the  muscles  of 
the  hypothenar  eminence,  as  well  as  the  interossei  muscles 
of  the  hand,  the  two  inner  lumbricales,  a  part  of  the  flexor 
brevis  poUicis,  and  the  adductor  pollicis  would  be  similarly 
affected.  Now,  the  clinical  evidences  of  this  form  of  paralysis 
are  in  perfect  accord  with  these  facts.  We  find  that  the  ad- 
duction of  the  hand  is  no  longer  performed  in  a  perfect  man- 
ner, since  the  flexor  carpi  ulnaris  can  no  longer  act  in  unison 
with  the  extensor  carpi  ulnaris ;  that  flexion  of  the  hand  is 
performed  imperfectly  and  by  means  of  the  flexor  of  the  ra- 
dial side  of  the  forearm  only,  since  that  muscle  is  supplied 
by  the  median  nerve  ;  that  the  ability  to  move  the  little  fin- 
ger is  almost  entirely  abolished  ;  that  complete  flexion  of  the 
inner  three  fingers  is  rendered  difficult  and  sometimes  impos- 
sible ;  that  the  fingers  can  not  be  separated  from  each  other, 
or  compressed  into  a  close  lateral  juxtaposition,  owing  to 
paralysis  of  the  interossei  muscles  ;  and  that  both  flexion  of 
the  first  phalanx  and  extension  of  the  two  terminal  pha- 
langes of  all  the  fingers  are  rendered  impossible,  for  the  same 
reason. 

When  the  ulnar  nerve  is  paralyzed  above  tJie  wrist,  so  that 
the  interossei  and  lumbricales  are  alone  paralyzed,  the  hand 

'  See  page  669  of  this  volume. 


690  THE  SPIRAL  NERVES. 

assumes  a  diagnostic  attitude,  the  so-called  '*  claw-hand,"  in 
which  the  extensor  communis  digitorum  muscle  extends  the 
first  phalanges  of  all  of  the  fingers,  while  the  other  two  rows 
of  phalanges  are  flexed  by  the  common  flexor  muscles  of  the 
fingers  (the  interossei  and  lumbricales  being  no  longer  able  to 
flex  the  first  row  of  phalanges  or  to  extend  the  two  other 
rows).  This  same  condition  of  the  hand  may,  however,  be 
produced  by  a  condition  of  progressive  muscular  atrophy  of 
these  muscles. 

It  must  be  remembered  that  this  condition,  if  dependent 
upon  ulnar  paralysis  alone,  is  more  marked  in  the  tico  inner 
fingers  than  in  the  three  outer,  since  the  lumbricales  are  sup- 
plied in  part  by  the  median  nerve ;  and  this  clinical  fact  seems 
to  stamp  the  action  of  the  lumbricales  as  similar  to  that  of  the 
interossei.  Finally,  the  effects  of  ulnar  paralysis  may  be 
manifested  in  the  movements  of  the  thumb,  since  it  supplies 
two  muscles  which  control  it.  This  will  be  most  apparent 
when  you  instruct  the  patient  to  press  the  thumb  forcibly 
against  the  metacarpal  bone  of  the  index  finger,  or  to  adduct 
the  thumb,  since  both  of  these  motions  will  be  rendered  diffi- 
cult or  impossible. 

These  disturbances  of  motility  create  serious  disturbances 
in  those  common  functions  in  which  the  hand  is  of  the  most 
service.  Writing,  drawing,  the  playing  of  musical  instru- 
ments, etc.,  are  rendered  difficult.  The  muscles  which  are 
supplied  by  the  median  and  radial  nerves  are  still  able,  how- 
ever, to  direct  the  hand  and  fingers  in  many  acts  which  con- 
tribute to  the  comfort  of  the  patient.  In  those  cases  where 
the  muscles  of  the  thenar  eminence  (supplied  chiefly  by  the 
median  nerve)  are  simultaneously  affected,  the  use  of  the 
hand  is  almost  entirely  abolished. 

THE  SUBSCAPULAR  NERVES. 

These  three  nerves  are  given  off  by  the  posterior  cord  of 
the  brachial  plexus.  They  are  called  the  upper,  long,  and 
lower  subscapular  nerves  by  some  authors,  while  the  numerical 
prefixes  of  first,  second,  and  third  are  applied  to  them  by 


THE  SUBSCAPULAR  NERVES.  691 

others.  As  will  be  seen  by  the  table  of  the  branches  of  the 
posterior  cord  of  the  brachial  plexus, '  the  first  or  upper  nerve 
supplies  the  subscapular  muscle,  the  second  or  long  nerve 
supplies  the  latissimus  dorsi,  and  the  third  or  lower  nerve 
supplies  the  teres  major,  whose  point  of  insertion  is  similar 
to  that  of  the  preceding  muscle,  since  the  tendons  of  the  two 
often  merge  into  each  other. 

Now,  these  three  muscles  are  agents  in  creating  certain 
movements  at  the  shoulder  joint ;  hence  it  is  to  be  presumed 
that  each  subscapular  nerve  sends  a  filament  to  that  articula- 
tion. I  am  aware  that  the  text-books  usually  give  the  credit 
of  nerve  supply  to  this  joint  to  other  sources,  since  the  fila- 
ments of  the  supra-scapular  and  circumfiex  nerves  can  be 
traced  easily  to  this  articulation  on  account  of  their  large  size, 
but  I  am  not  inclined  to  believe  that  an  axiom '  of  nerve  sup- 
ply, so  fully  sustained  in  other  regions,  will  not  fail  to  be 
supported  by  careful  dissections  of  this  part.  The  muscles 
supplied  by  the  subscapular  nerves  are  as  important  agents 
in  the  movements  of  the  arm  at  the  shoulder  as  those  supplied 
from  the  trunks  of  the  circumflex  and  the  supra-scapular 
nerves  ;  and,  if  it  be  true  that  a  joint,  when  exhausted  or 
inflamed,  can  control  the  muscles  which  move  it  by  means  of 
a  common  nerve  supply,  the  subscapular  nerves  must  cer- 
tainly be  eniimerated  as  one  of  the  sources  of  supply  to  the 
shoulder  joint. 

CLIJ^ICAL   POIN^TS   PERTAINING   TO   THE   SUBSCAPULAR   NERVES. 

These  nerves  are  seldom  the  seat  of  a  localized  neuralgia, 
or  of  paralysis,  except  in  connection  with  some  other  nerves 
of  the  upper  extremity.  The  situation  at  which  they  are 
given  off  from  the  brachial  plexus  (being  branches  of  the 
posterior  cord  and  imbedded  in  the  axillary  space)  is  a  safe- 
guard against  all  common  forms  of  external  violence,  while 
few  tumors  would  create  pressure  upon  these  trunks  without 
affecting  other  nerves  at  the  same  time,  and  possibly  to  an 
equal  or  greater  degree. 

*  See  page  6V0  of  this  volume.  ^  gg^  page  645  of  this  volume. 


692  THE  SPINAL  NERVES. 

Should  the  subscapular  nerves  happen  to  become  impaired, 
the  paralysis  would  be  shown  in  those  movements  of  the  arm 
which  are  performed  chiefly  by  the  three  muscles  supplied  by 
them.  The  latissimus  dorsi  could  no  longer  bring  the  hand 
into  the  position  assumed  when  scratching  the  anal  region  (in 
which  movement  it  is  prominently  concerned),  while  the  move- 
ment of  internal  rotation  at  the  shoulder  joint  would  be  im- 
paired, on  account  of  the  paralysis  of  the  subscapularis  and 
the  teres  major,  as  well  as  that  of  the  muscle  previously 
mentioned. 

Should  these  nerves  be  the  seat  of  degeneration,  as  in  the 
case  of  progressive  muscular  atrophy,  an  alteration  in  the  size 
of  the  latissimus  dorsi  and  teres  major  muscles  would  be 
detected,  and  the  other  symptoms  characteristic  of  this 
condition  might  be  discovered,  to  a  greater  or  less  degree, 
depending  upon  the  extent  of  the  muscular  changes. 

THE  CIRCUMFLEX  NERVE. 

This  nerve  arises  from  the  posterior  cord  of  the  brachial 
plexus,  usually  in  common  with  the  musculo-spiral  nerve, 
but  sometimes  by  an  independent  communication  with  the 
posterior  cord.  It  passes  downward  and  outward  behind  the 
axillary  artery  and  upon  the  subscapularis  muscle,  then 
backward  (in  company  with  the  circumflex  vessels)  through 
a  quadrilateral  space  bounded  by  the  humerus,  the  teres  ma- 
jor and  minor  muscles,  and  the  long  head  of  the  triceps,* 
when  it  divides  into  its  superior  and  inferior  branch.  It 
gives  off  a  distinct  branch  to  the  shoulder  joint,  before  its  two 
terminal  branches  are  formed,  in  the  vicinity  of  the  quadri- 
lateral space,  whose  boundaries  have  been  given. 

The  superior  branch  of  the  circumflex  nerve  is  the  larger 
of  the  two  terminal  filaments.  It  winds  around  the  neck  of 
the  humerus,  and  supplies  the  deltoid  muscle  and  the  integu- 
ment over  the  lower  portion  of  the  shoulder. 

The  inferior  branch  is  small  in  comparison  with  the  su- 
perior, and  is  distributed  to  the  teres  minor  muscle  and  the 

*  This  space  can  be  found  depicted  in  all  the  standard  text-books  upon  anatomy. 


THE  CIRCUMFLEX  NERVE. 


693 


integument  over  the  back  part  of  the  shoulder.  The  twig, 
given  off  to  supply  the  teres  minor  muscle,  is  sometimes  fur- 
nished with  a  ganglionic  enlargement. 


CLIJiTICAL   POINTS   PERTAINING   TO   THE   CIRCUMFLEX   NERVE. 

From  what  has  been  said  regarding  the  distribution  of  this 
nerve,  it  will  be  readily  understood  that  the  deltoid  and  teres 
minor  muscles,  as  well  as  the  integument  of  the  shoulder  and 


Fig.  209. —  Circumflex  and  suprascapular  nerves.     (Sappey.) 

1,  terminal  extremity  of  the  supra-scapular  nerve  ;  2,  branch  which  this  nerve  furnishes  to 
the  supra-spinatus  muscle  ;  3,  ramifications  by  which  it  terminates  in  that  muscle ; 
4,  circumflex  nerve  embracing  the  surgical  neck  of  the  humerus  ;  5,  filament  which 
this  nerve  sends  to  the  teres  minor  muscle ;  6,  cutaneous  nerve  to  the  shoulder ; 
7,  branches  of  the  circumflex  nerve  given  off  to  the  deltoid  muscle. 

upper  arm,  will  be  affected  by  any  impairment  of  the  circum- 
flex nerve.  A  fact  previously  mentioned,  however,  should 
not  be  lost  sight  of,  viz. ,  that  the  deltoid  muscle,  in  its  an- 
terior portion,  is  supplied  by  the  anterior  thoracic  nerves ; 
hence  the  impairment  of  the  circumflex  may  not  utterly  para- 
lyze it. 

The  intimate  relations  which  this  nerve  bears  to  the 
shoulder  joint  and  the  course  which  it  takes  around  the 
neck  of  the  humerus  render  it  particularly  liable  to  injury 
from  contusions,  concussions,  blows,  or  falls  upon  the  shoul- 


694:  THE  SPINAL  NERVES. 

der;  while  dislocations  of  the  humerus  from  the  scapula, 
especially  in  a  backward  direction,  are  frequently  followed 
by  deltoid  paralysis.  If  the  shoulder  joint  become  the  seat 
of  rheumatic,  or  any  other  type  of  chronic  inflammation,  the 
nerve  may  be  involved  in  a  neuritic  process,  and  thus  cause 
a  paralysis  of  the  deltoid  or  teres  minor  ;  while  the  same  re- 
sults may  also  follow  ''catching  cold,"  a  neuritis  being  prob- 
ably established.  Finally,  this  type  of  paralysis  may  follow 
injury  to  the  brachial  plexus,  all  the  forms  of  central  lesions, 
lead  poisoning,  and  progressive  muscular  atrophy. 

As  paralysis  of  the  teres  minor  muscle  can  not  be  easily 
detected,  provided  the  infra-spinatus  muscle  remains  unim- 
paired, the  symptoms  of  circumflex  paralysis  are  mostly  con- 
fined to  the  inability  to  perform  the  various  movements  into 
which  the  deltoid  muscle  prominently  enters.  The  arm  can 
not  be  raised  from  contact  with  the  wall  of  the  thorax,  by  any 
attempt  on  the  part  of  the  patient,  nor  can  it  be  brought  for- 
ward and  raised.  When  an  attempt  is  made  by  the  patient 
to  raise  the  arm,  the  deltoid  fibers  do  not  contract,  but  lie 
flabby  and  loose,  which  distinguishes  it  from  an  anchylosed 
condition  of  the  shoulder,  without  the  necessity  of  communi- 
cated motion  being  resorted  to  in  order  to  make  the  diagno- 
sis. The  deltoid  region  atrophies,  and  the  shoulder  joint 
becomes  relaxed.  A  deep  groove  can  often  be  detected 
through  the  atrophied  muscle  between  the  head  of  the  hu- 
merus and  the  articular  surface  of  the  scapula. 

THE  MUSCULO-SPIRAL  NERVE. 

This  is  the  largest  branch  of  the  brachial  plexus.  It  arises 
from  the  posterior  cord,  usually  in  company  with  the  circum- 
flex nerve,  and  lies  behind  the  third  portion  of  the  axillary 
artery,  at  its  point  of  escape  from  the  brachial  plexus.  It 
subsequently  passes  behind  the  upper  part  of  the  brachial 
artery,  crosses  the  tendons  of  the  teres  major  and  latissimus 
dorsi  muscles,  accompanies  the  superior  profunda  artery  in  a 
spiral  groove  upon  the  humerus,  and,  by  passing  between  the 
supinator  longus  and  the  brachialis  anticus  muscles,  it  reaches 


THE  MUSCUL0-8PIRAL  NERVE. 


695 


K 


Fig.  210. — Musculo-spiral  net've.  Fig.  211. —  Terminal  branches  of  the 

(Sappey.)  musculo-spiral  ne^'ve.     (Sappey.) 

Fig.  210. — 1,  circumflex  nerve ;  2,  filament  to  the  teres  minor  muscle ;  3,  cutaneous  branch 
of  the  circumflex ;  4,  trunk  of  the  musculo-spiral ;  5,  portion  of  this  nerve  which  cor- 
responds to  the  spinal  groove  of  the  humerus ;  6,  this  same  nerve  passing  between 
the  brachialis  anticus  and  supinator  longus  muscles  ;  Y,  branch  which  the  musculo- 
spiral  furnishes  to  the  long  head  of  the  triceps  muscle ;  8,  8,  branch  to  the  internal 
portion  of  this  muscle  ;  9,  branch  to  the  external  portion  of  this  muscle;  10,  termi- 
nal branch  of  this  same  nerve  distributed  to  the  anconeus  muscle;  11,  another 
branch  of  the  same  nerve  supplying  also  the  external  portion  of  the  triceps  muscle ; 
12,  external  cutaneous  branch  of  the  musculo-spiral. 

Fig.  211. — 1,  trunk  of  the  musculo-spiral  nerve  ;  2,  branch  to  the  supinator  longus  muscle ; 
3,  branch  to  the  extensor  carpi  radialis  longior;  4,  branch  to  the  extensor  carpi 
radialis  brcvior ;  5,  bifurcation  of  this  trunk ;  6,  its  posterior  or  muscular  branch ; 
7,  the  same  branch  crossing  the  supinator  brevis,  to  which  it  gives  off  several  small 
branches ;  8,  its  terminal  divisions  ;  9,  anterior  or  cutaneous  branch  of  this  nerve ; 
10,  terminal  divisions  of  this  branch;  11,  musculo-cutaneous  nerve  ;  12,  12,  12,  its 
terminal  divisions  ;  13,  one  of  these  branches  which  descends  as  far  as  the  wrist,  and 
then  anastomoses  with  the  cutaneous  branch  of  the  radial. 


696  THE  SPINAL  NERVES.  > 

the  external  condyle  of  the  humerus,  where  it  divides  into  i 
two  terminal  branches,  viz.,  the  radial  and  the  posterior  in-  '' 
terosseous  nerves.  t 

The  table  of  the  branches  given  off  from  the  posterior  cord 
of  the  brachial  plexus,'  and  the  filaments  of  distribution  of  1 
each,  will  help  you  in  following  the  chief  points  of  interest  j 
associated  with  this  nerve.     It  will  be  perceived  that  the  main  i 
trunk  of  the  nerve  supplies  five  muscles,  while  the  posterior  ! 
interosseous  branch  supplies  all  the  remaining  muscles  upon 
the  posterior  surface  of  the  forearm.     This  nerve  is,  therefore, 
essentially  an  extensor  nerve,  although  the  brachialis  anticus  = 
and  supinator  longus  muscles  assist  in  flexion  of  the  forearm.  J 
When  we  come  to  the  consideration  of  the  effects  of  paraly-  I 
sis  of  this  nerve,  the  special  symptoms  will  help  still  further  } 
to  impress  upon  you  the  distribution  of  its  branches  to  mus- 
cles as  well  as  to  the  integument ;  and  the  points  of  interest,  j 
which  depend  upon  the  peculiar  course  of  the  main  trunk  of  ] 
the  nerve,  will  be  made  prominent,  as  an  explanation  of  the  ; 
frequent  occurrence  of  this  special  type  of  paralysis  in  cer-  \ 
tain  occupations.  " 

The  radial  hrancli  is  exclusively  distributed  to  the  integu-  \ 
ment,  as  is  shown  in  the  table,'  and  the  special  distribution  of  \ 
the  branches  given  off  by  this  nerve  to  the  integument  of  the  ) 
hand  has  been  already  discussed  at  some  length  in  a  previous  , 
lecture.'  ^ 

The  musculo-spiral  nerve  gives  an  articular  filament  to  the 
wrist  joint,  by  means  of  its  posterior  interosseous  branch ;  ; 
and,  probably,  some  filaments  also  to  the  elbow  joint,  if  j 
we  accept  the  general  law  of  nerve  distribution  given  by  " 
Hilton,  so  often  quoted  in  the  preceding  lectures  of  this  i 
course.  i 

We  are  now  prepared  to  examine,  with  advantage,  the  dia-  \ 
grammatic  plates,*  in  which  the  regions  supplied  by  the  dif-  | 
ferent  nerves  of  the  upper  extremity  are  exhibited  more  . 
clearly  than  a  verbal  description  could  alone  afford.     They 

'  See  page  670  of  this  volume.        *  See  page  670  of  this  volume.  | 

'  See  page  688  of  this  volume.        "*  See  cuts  on  pages  682  and  697  of  this  volume.      i 


DISTRIBUTION  OF  MUSCULO-SPIRAL  NERVE. 


697 


will  prove  of  great  assistance  in  studying  the  tables'  in 
wMcli  the  branches  of  the  individual  nerves  are  classified. 


Fig.  212. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  on  the  posterior  sur- 
face of  the  upper  extremiii/  and  trunk. 

18,  rec^ion  supplied  by  the  seco7id  dorsal  nerve  ;  19,  region  supplied  by  the  supra-scapular 
nerve;  20,  region  supplied  by  the  circumflex  nerve  ;  21,  region  supplied  by  the  inter- 
cosio-humeral  nerve ;  22,  region  supplied  by  the  external  cutaneous  nerve ;  28,  region 
supplied  by  the  internal  cutaneous  branch  of  the  musculo-spiral  nerve  ;  24,  region 
supplied  by  the  "werwe  of  Wrisberg  ; ''^  25,  region  supplied  by  the  lateral  branches 
of  the  intercostal  nerves ;  26,  region  supplied  by  the  internal  cutaneous  nerve ;  2Y,  re- 
gion supplied  by  the  muscido-cutancous  nerve ;  28,  region  supplied  by  the  iliac  branch 
of  the  ilio-inguinal  nerve ;  29,  region  supplied  by  the  radial  nerve ;  30,  region  sup- 
plied by  the  ulnar  nerve. 

This  diagram  limits  the  distribution  of  each  nerve  with 
more  positiveness  than  can  be  well  verified,  since  the  cuta- 

^  See  tables  on  pages  669,  670,  and  6Y1  of  this  volume. 


698  THE  SPINAL  NERVE8. 


neons  filaments  of  two  nerves  may  supply  the  borders  of  any 
of  these  regions,  as  the  nerves  tend  to  overlap  each  other.  It 
is  not  well,  therefore,  to  rely  positively  upon  the  border  limits 
of  any  region  in  your  endeavors  to  detect  anaesthesia,  should 
you  suspect  a  paralytic  condition  of  any  special  nerve,  and 
seek  this  means  of  confirming  your  diagnosis. 

The  rule  of  Hilton  would  naturally  cause  us  to  expect  that 
the  muscles  supplied  by  any  special  nerve  would  act  as  a 
guide  in  determining  the  source  of  the  cutaneous  nerve  supply 
over  the  points  of  attachments  of  those  muscles  ;  and  we  are 
not  disappointed  when  we  examine  closely  the  area  of  cuta- 
neous distribution  of  the  musculo-spiral  nerve.  This  nerve 
supplies  the  supinators  of  the  hand,  the  extensor  muscles  of 
the  elbow  joint  and  of  the  wrist  joint,  and  the  extensor  mus- 
cles of  the  fingers  and  the  thumb  ;  hence  we  find  the  skin 
over  these  groups  of  muscles  supplied,  to  a  great  extent,  by 
the  same  nerve  which  a£Pords  motor  power  to  the  muscles  un- 
derneath. This  fact  will  thus  help  you  to  remember  the  area 
of  distribution  of  any  nerve  to  the  skin  by  a  process  of  rea- 
soning based  upon  the  muscles  which  are  supplied  by  the  same 
nerve,  and  the  numerous  examples,  already  quoted  in  confir- 
mation of  this  general  law,  prove  that  the  deduction  drawn 
from  it  is,  in  all  cases,  approximately  accurate. 

CLINICAL   POINTS   PEKTAINING  TO  THE   MUSCULO-SPIKAL  NERVE. 

The  musculo-spiral  nerve  is  more  frequeittly  affected  with 
paralysis  than  any  of  the  nerves  of  the  upper  extremity.  It 
is  particularly  liable  to  both  peripheral  and  central  causes  of 
paralysis ;  thus,  in  cerebral  hemiplegia,  the  muscles  supplied 
by  this  nerve  are,  perhaps,  more  commonly  affected  than  those 
supplied  by  any  other  nerve,  while  paralysis  of  these  muscles 
is  common  as  the  result  of  chilling  of  the  upper  extremity, 
traumatism,  and  lead  poisoning. 

The  anatomical  situation  of  the  musculo-spiral  nerve  and 
the  peculiarity  of  its  course  around  the  humerus  probably  ex- 
plain the  frequent  occurrence  of  paralysis,  since  it  may  be 
easily  compressed  by  sleeping  upon  the  aim.     It  is  common 


i 


CLINICAL  POINTS  AFFORDED  BY  MU8GUL0-SPIRAL  NERVE. 

to  meet  with  tMs  type  of  paralysis  in  patients  who  have  used 
their  arm  as  a  pillow,  or  in  drunkards  who  have  slept  in  some 
constrained  position  upon  benches,  steps,  etc.  Persons  who 
have  fallen  exhausted  and  have  rested  upon  the  arm,  and  sol- 
diers who  have  slept  upon  the  damp  ground,  often  arise  with 
this  form  of  paralysis.  It  is  stated  by  Brenner '  that  the  coach- 
men of  Russia,  who  are  in  the  habit  of  sleeping  upon  the  box 
with  the  reins  wound  around  the  upper  arm,  are  victims  to 
this  condition ;  and  Bachon '  reports  the  same  result  as  com- 
mon among  the  water-carriers  of  Rennes,  since  they  pass  their 
arm  through  the  handle  of  the  heavy  water-pails  to  more  se- 
curely compress  them  against  the  chest.  The  habit  of  the 
Russians  of  tightly  bandaging  the  arms  of  infants  to  the  body, 
and  allowing  them  to  sleep  upon  one  side  for  long  intervals, 
seems  to  promote  the  frequent  occurrence  of  this  trouble. 

Among  the  other  forms  of  injury  which  conduce  toward 
this  form  of  paralysis  may  be  mentioned  the  use  of  poorly 
padded  crutches,  the  kicks  of  animals,  cuts,  stab  wounds, 
fractures  of  the  humerus,  dislocation  of  the  humerus  at  the 
shoulder  joint,  and  the  development  of  an  excessive  amount 
of  callus  after  a  fracture. 

Rheumatic  affections  and  a  neuritis  of  the  musculo-spiral 
nerve  are  reported  as  causes  by  Bernhardt  and  others ;  and 
cases  of  hysterical  origin  have  been  rarely  but  positively  au- 
thenticated. 

Finally,  lead  poisoning  must  be  mentioned  as  one  of  the 
most  common  causes  of  paralysis  of  the  muscles  supplied  by 
the  musculo-spiral  nerve.  The  existence  of  this  form  of  poi- 
soning will  have  generally  been  indicated,  previous  to  the  ap- 
pearance of  paralysis,  by  colic,  jaundice,  and  arthralgia,  as 
the  muscles  are  seldom  affected  until  the  latter  stages.  The 
extensor  communis  digitorum  muscle  is  usually  affected  first, 
and  the  paralysis  gradually  extends  to  the  other  muscles  sup- 
plied by  the  musculo-spiral  nerve.  The  muscles  of  the  arm 
are  much  less  frequently  affected  than  those  of  the  hand  and 
forearm ;  but,  in  severe  cases,  the  muscles  of  the  upper  arm, 

*  As  quoted  by  Erb.  ^  As  quoted  by  Erb. 


TOO  TEE  SPINAL  NERVES. 

shoulder,  and  even  those  of  the  lower  extremity,  may  become 
involved. 

It  is  difficult  as  yet  to  explain  the  apparent  predisjDosition 
of  lead  poisoning  to  affect  the  muscles  of  the  musculo-spiral 
region  in  preference  to  the  flexor  muscles.  Gombault,  Bern- 
hardt, Westphal,  Barwinkel,  Hitzig,  and  Lancereaux  have 
given  special  attention  to  the  subject,  and  arrived  at  no  com- 
mon ground  upon  which  they  can  all  agree.  The  condi- 
tion has  been  explained  as  the  result  of  a  venous  stasis  (Hit- 
zig), and  as  the  result  of  arterial  ischsemia  (Barwinkel) ;  both 
of  whom  regard  these  conditions  as  favoring  the  deposition 
of  lead  in  the  muscles  of  the  extensor  region  of  the  fore- 
arm. Peripheral  nerve  degeneration  has  been  claimed  as 
the  explanation  of  the  paralytic  symptoms  by  Gombault, 
Westphal,  and  Lancereaux,  and  in  this  view  the  investiga- 
tions of  Neuman,  Erb,  and  Eichhorst  coincide.  Whether  a 
spinal  origin  will  be  yet  determined  which  will  explain  the 
muscular  changes  and  the  loss  of  power,  is  yet  to  be  decided 
by  further  pathological  research. 

The  symptoms  which  characterize  this  type  of  paralysis 
have  such  a  distinctive  form  as  to  be  easily  recognizable  by 
the  physician  at  the  very  first  glance.  A  reference  to  the 
table  which  shows  the  distribution  of  the  musculo-spiral 
nerve  to  muscles'  will  help  to  explain  them.  We  see  that 
this  nerve  sends  filaments  to  the  triceps  and  brachialis  anticus 
muscles  in  the  arm,  and  to  all  the  extensor  muscles  of  the 
forearm.  In  accordance  with  this  distribution,  the  hand  is 
kept  in  a  state  of  flexion  when  this  nerve  is  paralyzed,  and 
can  not  be  raised  or  extended ;  the  thumb  is  flexed  and  ad- 
ducted  ;  and  the  fingers  are  flexed  and  cover  the  thumb. 
When  the  patient  attempts  to  extend  the  fingers,  the  interos- 
sei  and  lumbricales  muscles  alone  can  be  made  to  act,  and 
these  muscles,  as  has  been  mentioned  before,  can  only  extend 
the  two  tenninal  phalanges  while  they  flex  the  basal  phalanx.' 

'  See  page  670  of  this  volume. 

*  The  explanation  of  this  fact  lies  in  the  insertion  of  the  tendons  of  these  muscles 
into  the  tendons  of  the  common  extensor  of  the  fingers. 


J 


MUSGVLO-SPIRAL  PARALYSIS. 


701 


The  thumb  and  the  index  finger  can  not  be  extended  or 
abducted ;  the  patient  can  not  supinate  the  hand  when  the 
forearm  is  extended  (this  position  being  assumed  in  or- 
der to  exclude  the  action  of  the  biceps  muscle),  nor  can 
the  forearm  be  half  bent  and  the  hand  half  supinated  by 
the  supinator  longus  muscle ;  and,  finally,  when  the  patient 
is  instructed  to  flex  the  forearm,  when  placed  in  a  position 
of  half  flexion  and  semi-prostration,  the  supinator  longus 
muscle  lies  flaccid,  and  does  not  become  tense  and  hard  as 
in  health.  The  loss  of  power  in  the  triceps  muscle  ren- 
ders it  impossible  for  the   patient  to  extend  the  forearm 


M.  external  head  of  triceps 


Musculo-spiral  nerre ^^^""""#  = 

M.  brachialis  anticus ^^J!»         -^ 

M.  supinator  longus 

M.  extensor  carpi  rad.  longior. 

M.  extensor  carpi  rad.  brevior.      .^f^iiS-^^ 


Fig.  213. — The  motor  points  on  the  outer  aspect  of  the  arm. 


upon  the  arm  when  the  arm  is  first  raised  above  the  head ; 
nor  can  the  forearm  be  extended  with  the  same  degree  of 
force  as  the  healthy  side  in  any  position  of  the  arm. 
When  the  hand  is  laid  upon  the  table,  the  patient  is  un- 
able to  raise  the  hand  from  contact  with  it,  but  the  lateral 

movements  of  the  fingers  can  be  performed  as  in  health, 

47 


702 


THE  SPINAL  NERVES. 


since  these  movements  are  controlled  by  the  interossei  mus- 
cles.    The  action  of  the  flexor  muscles  of  the  wrist  seems 
feeble,  since  the  antagonistic  action  of  the  extensors  does  not : 
afford  a  fixed  point  of  action ;  but,  if  the  wrist  be  forcibly ; 
extended  and  fixed,  it  will  be  seen  that  the  wrist  flexors  are  | 
not  paralyzed. 

This  form  of  paralysis  interferes  with  almost  all  of  the  nu- 
merous employments  of  daily  life,  since  the  functions  of  the 
hand  are  most  seriously  impaired.  The  patient  can  not  well 
hold  or  grasp  anything,  on  account  of  the  inability  to  perform  | 


7    8 


Fig.  214, — The  motor  points  on  the  inner  side  of  the  arm.  1 

1,  m.  internal  head  of  triceps;  2,  musculo-cutaneous  nerve;  8,  median  nerve;  4,  m.  i 
coraco-brachialis ;  5,  ulnar  nerve ;  6,  branch  of  median  nerve  for  pronator  radii ; 
teres ;  7,  musculo-cutaneous  nerve  ;  8,  m.  biceps  flexor  cubiti.  j 


the  extension  of  the  thumb  or  fingers  ;  and  the  impairments 
of  the  supinators  still  further  adds  to  the  uselessness  of  the| 
hand.  The  regions  of  the  integument  supplied  by  the  mus- 
culo-spiral  nerve  exhibit  more  or  less  ansesthesia,  although  j 
the  extent  of  this  symptom,  like  that  of  the  muscular  pa-^ 
ralysis,  is  modified  by  the  height  of  the  lesion,  which  affects  J 
the  nerve  as  well  as  by  its  character.  In  some  cases,  exten-  ^ 
sive   motor  paralysis  may  be  present  without  any  marked  i 


ji 


MUSCULOSPINAL  PARALYSIS. 


703 


disturbance  of  sensibility;   this   can  only  be  explained  by 
tlie  presence  of  anastomosis  between  the  cutaneous  nerves 


Fig.  215. — T^ie  motor  points  on  the  extensor  (posterior)  aspect  of  the  forearm. 

1,  m.  supinator  longus;  2,  m.  extensor  carpi  rad.  longior ;  3,  ra.  extensor  carpi  rad.  bre- 
vier; 4,  5,  m.  extensor  communis  digitorum;  6,  m.  extensor  ossis.  met.  pol. ;  7,  m. 
extensor  primi.  internod.  pol. ;  8,  m.  first  dorsal  interosseous ;  9,  m.  second  dorsal 
interosseous;  10,  m.  third  dorsal  interosseous;  11,  m.  extensor  carpi  ulnaris;  12,  m. 
extensor  min.  digiti;  13,  m.  extensor  secund.  internod.  pol.;  14,  m.  abduct,  min. 
digiti;  15,  m.  fourth  dorsal  interosseous. 


of  different  origins,  as  was  demonstrated  by  Tripier  and  Ar- 
loing*  upon  dogs. 

In  the  diagnosis  of  this  type  of  paralysis,  it  is  often  diffi- 
cult to  determine  the  exact  nature  and  seat  of  the  exciting 

*  As  quoted  by  Erb. 


704 


TEE  SPINAL  NERVES. 


cause.     The  most  common  causes  are  injury,  pressure,  and 
lead  poisoning ;  but  the  existence  of  exciting  neuritis,  some 


1 

i 


Fig.  216.— 7%e  motor  points  on  the  flexor  (anfei-ior)  aspect  of  the  forearm. 
1,  median  nerve  and  branch  to  m.  pronator  radii  teres ;  2,  m.  palmaris  longus ;  3,  m. 
flexor  carpi  ulnaris  :  4,  m.  flexor  sublim.  digit. ;  5,  ulnar  nerve ;  6,  m.  flex,  subliin. 
dig. ;  7,  volar  branch  of  the  ulnar  nerve  ;  8,  m.  palmaris  brevis ;  9,  m.  abductor  rain, 
digit. ;  10,  m.  flexor  rain,  digit. ;  11,  in.  opponens  min.  digit. ;  12,  13,  m.  lumbricales; 
14,  m.  flexor  carpi  radialis  -,"15,  m.  flexor  profund.  digitorum  ;  16,  m.  flexor  sublim. 
digitorum;  17,  in.  flex,  longus  poUicis ;  18,  median  nerve;  19,  m.  opponens  polhcis; 
20,  m.  abductor  pollicis  ;  21,  m.  flexor  brevis  pollicis;  22,  m.  adductor  pollicis ;  28,  ^ 
m.  first  lumbricalis. 


cerebral  disease,  or  an  hysterical  cause,  must  be  excluded  -_^ 
determined  by  the  concomitant  symptoms.     When  the  paral 


THE  DORSAL  NERVES.  705 

ysis  is  due  to  local  compression,  tlie  triceps  muscle  is  not  usu- 
ally affected,  and  the  same  statement  applies  to  the  rheumatic 
form,  while  in  both  of  these  types  the  disturbance  of  sensi- 
bility is  most  frequently  confined  to  the  hand  alone.  In  lead 
paralysis,  the  supinator  brevis  muscle  remains  unaffected 
until  late  in  the  disease,  and  the  supinator  longus  muscle 
is  rarely  involved,  even  in  severe  forms  of  poisoning.  While 
this  can  not  be  taken  as  an  absolute  sign,  it  is  a  most 
valuable  point  in  diagnosis,  and  should  be  always  remem- 
bered. In  addition  to  the  muscular  paralysis,  lead  poison- 
ing is  often  accompanied  by  muscular  atrophy  and  swell- 
ing of  the  veins  Upon  the  extensor  side  of  the  forearm ; 
while  tendinous  swellings  are  frequently  detected  in  the 
region  of  the  wrist. 

The  duration  of  paralysis  of  the  musculo-spiral  nerve  de- 
pends largely  upon  the  exciting  cause.  Lead  poisoning  pro- 
duces, in  all  cases,  an  exceedingly  slow  and  obstinate  form  of 
trouble,  and  the  paralysis  may  be  incurable  ;  '' crutch  paraly- 
sis" usually  recovers  speedily,  if  the  pressure  be  discontinued ; 
traumatic  paralysis,  if  the  injury  be  severe,  follows  a  protract- 
ed course  ;  while  those  cases  which  depend  upon  cerebral 
origin  are  modified,  as  to  their  course  and  termination,  by  the 
character  of  the  exciting  lesion. 


THE   DORSAL  NERVES. 

The  nerves  of  the  dorsal  region  are  twelve  in  number  upon 
each  side  of  the  trunk.  They  escape  from  the  vertebral  canal 
by  means  of  foramina  between  the  dorsal  vertebrae,  and  are 
connected  to  corresponding  ganglia  of  the  sympathetic  nerve. 
Each  dorsal  nerve  is  joined  to  a  ganglion  of  the  sympathetic, 
immediately  after  its  escape  from  the  foramen  between  the 
vertebrae,  by  two  small  and  short  filaments  ;  hence,  there  are 
frequent  points  of  communication  between  the  cerebro-spinal 
and  sympathetic  systems  of  nerves  throughout  the  length  of 
the  vertebral  column.  As  has  been  stated  in  a  previous  lec- 
ture, the  first  dorsal  nerve  assists  to  form  the  brachial  plexus, 


706 


THE  SPIRAL  NERVES. 


and  can  therefore  be  properly  classed  as  one  of  tlie  nerves  of 
the  tipper  extremity  rather  than  a  nerve  of  the  trunk ;  the 
remaining  nerves  of  this  region  are  distributed  entirely  to 
the  parietes  of  the  thorax,  the  adjacent  pleura,  and  the  in- 
tegument covering  the  front,  sides,  and  back  of  the  chest, 
and  the  upper  part  of  the  abdomen. 

The  table  which  I  now  show  you  is  designed  to  make  the 
general  distribution  of  the  dorsal  nerves  easy  of  comprehen- 
sion, and  to  assist  in  reviewing  the  chief  points  of  interest 
which  are  presented  in  connection  with  the  nerves  of  this 
region. 

NERVES  OF  THE  DORSAL  REGION. 


Posterior 
divisions. 


DORSAL    , 
NERVES.  < 


Anterior 
divisions. 


External   , 
branches.  ' 


Internal 
branches. 


Six 

upper  or 

thoracic 

intercos- 

tals. 


Six 

lower  or 
thoracico- 

ahdomi- 
nal  inter- 

costals. 


In  upper 

six 
nerves. 

In  the 
lower  six 

nerves. 

In  upper 

six 

nerves. 

In  the 

lower  six 

nerves. 
Muscular 
branches. 

Lateral 
cutane- 
ous. 

Anterior 
cutane- 
ous. 
Muscular 
branches. 

Lateral 
ciUaneoits. 

Anterior 
cutaneous. 


Filaments  to  transversalis  colli, 
Filaments  to  longissimus  dorsi, 
Filaments  to  trachelo-mastoid, 
Filaments  to  levatores  costarum, 
Filaments  to  sacro-lumbalis, 
Filaments  to  accessorius. 
Same     muscles     as    in    preceding 

bracket, 
Integument  of  the  back. 
Filaments  to  semispinalis  dorsi, 
Filaments  to  multifidus  spinae, 
Integument  of  back. 
Same    muscles    as    in    preceding 

bracket, 
No  cutaneous  filaments. 
Intercostals, 
Triangularis  sterni. 
Integument  of  chest  and  mammae. 
Upper,  part   of    external    oblique 

muscle, 
Integument  over  upper  part  of  latis- 
simus  dorsi  and  the  scapular  re- 
gion. 

Integument  of  mammae  and  side  of 
the  chest. 

Intercostals, 

Abdominal  muscles. 

J7itegument  of  abdomen,  as  far  as 
the  edge  of  rectus. 

Integument  over  lower  part  of  latis- 
simus  dorsi. 

Upper  part  of  rectus  and  integu- 
ment in  front  part  of  abdomen. 


It  will  be  perceived  that  these  nerves,  like  those  of  the< 
cervical  region,  divide  into  anterior  and  posterior  branches,  ^ 
in  the  immediate  vicinity  of  the  vertebral  column.  The  pos-< 
terior  divisions  supply  the  muscles  of  the  back  and,  the  in-! 


DISTRIBUTION  OF  THE  DORSAL  NERVES. 


707 


tegument  wMcli  covers  that  region,  while  the  anterior  divis- 
ions supply  the  muscles  of    respiration  and  some   of  the 


217. —  Tlie  iniei'costal  nerves.     (Masse.) 

The  pectoralis  major  and  minor  muscles  are  removed.  The  obliquus  externus  and  rectus 
abdominis  are  divided,  and  removed  in  some  places. 

1,  axillary  vein :  the  artery  is  removed ;  2,  portion  of  the  brachial  plexus  and  two  tho- 
racic brahches ;  3,  brachial  twig  of  the  first  intercostal  nerve  ;  4,  brachial  twig  of  the 
second  intercostal  nerve ;  5,  inosculation  between  two  branches ;  6,  division  of  an 
intercostal  branch  into  7,  a  superficial  branch,  and  8,  a  deep  branch ;  9,  gluteal 
branch  of  the  twelfth  intercostal  nerve ;  10,  termination  of  the  ilio-scrotal  branch 
of  the  lumbar  plexus  ;  II,  inguino-cutaneous  branch;  12,  twig  of  the  genito-crural 
branch ;  13,  13,  portions  of  the  deep  nerves  after  they  have  become  superficial. 

abdominal  muscles,  and  the  integument  of  the  chest,  loins, 
and  abdomen.     The  intercostal  nerves  are  formed  entirely 


708  THE  SPINAL  NERVES, 

from  the  anterior  divisions ;  tliose  arising  from  the  upper 
half  of  the  dorsal  region  being  called  the  ''  thoracic  "  intercos- 
tals,  while  the  lower  six  nerves  are  called  the  "thoracico- 
abdominal"  intercostal  nerves. 

The  first  and  last  dorsal  nerves  are  somewhat  peculiar  in 
their  distribution,  and  deserve  a  special  description.  The  first 
dorsal  nerve  has  no  lateral  cutaneous  branch,  since  the  branch 
which  corresponds  to  the  lateral*  cutaneous  branch  of  the 
other  nerves  is  of  large  size,  and  enters  into  the  formation  of 
the  brachial  plexus.  The  continuation  of  this  nerve  along 
the  first  intercostal  space  is  of  small  size,  and  ends  in  the  an- 
terior cutaneous  nerve. 

The  last  dorsal  nerve  is  the  largest  of  the  twelve,  and  is 
usually  connected  with  the  first  lumbar  nerve  by  a  filament 
called  the  '^dorso-lumbar"  nerve,  which  descends  in  the 
substance  of  the  quadratus  lumborum  muscle.  It  com- 
municates also  with  the  hypogastric  branch  of  the  ilio-hy- 
pogastric  nerve  (a  branch  of  the  lumbar  plexus),  between 
the  internal  oblique  and  transversalis  muscles  of  the  ab- 
domen. Its  lateral  cutaneous  branch  is  very  large,  and  is 
distributed  to  the  integument  of  the  front  part  of  the  gluteal 
region. 

The  distribution  of  the  dorsal  nerves  to  the  costal  layer  of 
the  pleura  is  not  specially  designated  in  the  table,'  but  it  is  a 
fact  of  great  physiological  interest.  Hilton  draws  an  analogy 
between  the  pleura  and  a  synovial  membrane  of  a  joint ;  and 
the  intercostal  muscles  are  also  compared  by  him  to  those 
moving  a  joint.  Thus  this  author  adduces  further  proof  of 
his  general  law  of  nerve  distribution,  since  the  skin  of  the 
chest,  the  intercostal  muscles,  and  pleura  are  supplied  from 
the  same  source.  In  pursuing  this  same  line  of  reasoning 
(and  the  analogy  is  not  a  strained  one  from  a  physiological 
standpoint),  the  abdominal  muscles  might  also  be  included 
among  the  list  of  muscles  which  move  the  ribs  ;  and  the  nerVe 
supply  to  them  also  would  thereby  be  explained  by  this  same 
axiom,  viz.,  that  the  nerves  which  supply  a  joint  supply  the 

*  See  page  706  of  this  volume. 


DISTRIBUTION  OF  TEE  DORSAL  NERVES. 


709 


muscles  which  move  it  and  the  skin  over  the  insertions  of 
those  muscles. 

It  should  be  recollected  that  some  of  the  filaments  derived 


Fig.  218. — The  nerves  situated  on  the  posterior  part  of  the  trunk.     (Masse.) 

Portions  of  the  trapezius,  splenius,  complexus,  trachelo-raastoideus,  latissimus  dorsi,  and 
gluteus  maximus  muscles,  etc.,  etc.,  are  removed. 

1,  1,  1;  posterior  twigs  of  the  superficial  branches  of  the  intercostal  nerves;  2,  posterior 
branch  of  the  first  cervical  nerve,  or  sub-occipital ;  3,  posterior  branch  of  the  second 
cervical  nerve;  4,  inosculation  of  this  branch  with  the  great  mastoid  branch;  5,  5, 
posterior  branches  of  two  cervical  nerves  ;  6,  intercostal  branch ;  V,  external  twig  of  a 
dorsal  branch  ;  8,  internal  twig  of  a  dorsal  branch ;  9,  posterior  branch  of  a  lumbar 
nerve ;  10,  posterior  branch  of  a  sacral  nerve. 


710  TEE  SPINAL  NERVES.  j| 

li 
from  tlie  upper  intercostal  nerves  cross  the  axillary  space  \ 

and  supply  the  integument  of  the  arm.     The  "  nerve  of  Wris-  • 

berg,"  which  has  been  described  in  connection  with  the  cuta-  \ 

neous  nerves  of  the  arm,  is  perhaps  the  most  important  of 

these  branches.     It  may  thus  be  understood  why  the  pain  of  j 

pleuritic  inflammation  may  be  carried  to  and  felt  in  the  region  j 

of  the  axilla  and  inner  arm,  and  why  distinct  points  of  tender-  '. 

ness  to  pressure  may  sometimes  be  detected  in  these  regions  ^ 

when  the  disease  is  confined  to  the  trunk.  j 

CLIN^ICAL  POINTS   PERTAINING  TO  THE   DORSAL  NERVES.  v 

From  the  suggestions  thrown  out  as  to  the  physiological  ' 
importance  of  nerve  distribution,  and  from  the  fact  that  the  \ 
pleura  is  supplied  from  the  same  nerve  sources  as  the  respira- 
tory muscles  and  the  integument  of  the  chest,  abdomen,  and  \ 
inner  arm,  some  important  clinical  lessons  may  be  drawn.  I 
Patients  suffering  from  pleurisy  feel  a  pain  in  the  costal  j 
muscles  which  compels  restricted  movement  of  the  ribs,  and  ' 
which  limits  the  respiratory  function  largely  to  the  diaphragm. 
Now,  these  painful  cramps  and  stitches  are  independent  of  \ 
the  pain  arising  alone  from  the  inflamed  pleural  surface,  and  j 
the  diminution  of  the  respiratory  movements  is  due  to  a  par-  \ 
tially  contractured  state  of  the  muscles  of  the  chest,  as  is  de-  j 
monstrated  by  the  fact  that  patients  can  not  draw  a  long  breath  .^ 
if  asked  to  do  so  ;  lience,  we  may  reasonably  conclude  that  •:; 
Nature  has  so  distributed  the  nerves  to  the  pleura  as  to  en-  ., 
able  that  serous  membrane  to  control  the  muscles  which  \ 
create  movement  of  the  adjacent  costal  surfaces,  and  thus  j 
insure  its  quietude  during  the  stages  of  inflammation  or  < 
repair.  It  is  wisely  suggested  by  Hilton,  in  this  connection,  i 
that  we  learn  a  lesson  in  the  treatment  of  such  cases  from  l-^ 
Nature  herself,  viz.,  "  never  to  allow  a  patient,  suffering  from 
pleurisy  or  pneumonia,  to  talk  except  in  monosyllables,  so  as  ., 
to  avoid  a  full  inspiration."  a 

The  diagnostic  value  of  pain  is  well  exemplified  in  the  J| 
region  of  the  thorax.  Persistent  pains  high  up  between  the  j 
shoulders  are  strongly  indicative  of  diseases  of  the  heart, 


CLINICAL  POINTS  AFFORDED  BY  THE  DORSAL  NERVES  711 

aneurism  of  the  arch  of  the  aorta,  stricture  of  the  oesophagus, 
and  anything  which  would  tend  to  create  pressure  within  the 


11 


Fig.  219. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  in  the  antei'ior  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

1,  region  supplied  by  the  supra-clavicular  nerve  (branch  of  the  cervical  plexus) ;  2,  re- 
gion supplied  by  the  circumflex  nerve  ;  3,  region  supplied  by  the  intercosto-humeral 
nerve ;  4,  region  supplied  by  the  intercostal  nerve  (lateral  branch) ;  5,  region  sup- 
plied by  the  lesser  internal  cutaneous  nerve  (nerve  of  Wrisberg) ;  6,  region  supplied 
by  the  musculo-spiral  nerve  (external  cutaneous  branch) ;  7,  region  supplied  by  the 
internal  cutaneous  nerve ;  8,  region  supplied  by  the  musculo-cutaneous  nerve ;  9, 
region  supplied  by  the  median  nerve  ;  10,  region  supplied  by  the  ulnar  nerve ;  11, 
region  supplied  by  the  intercostal  nerve  (anterior  branch). 

posterior  mediastinum.'    If  we  meet  with  persistent  pain  in 
the  space  lying  between  the  middle  of  the  scapula  and  the 

^  John  Hilton,  op.  cit. 


712  TEE  SPINAL  NERVES, 

lumbar  region  of  the  spiTW^  we  may  have  good  grounfl.  to  sus- 
pect the  existence  of  some  disease  of  the  abdominal  digestive 
viscera,  the  pain  being  carried  to  the  surface  probably  by 
means  of  the  splanchnic  nerves.'  It  is  not  uncommon  for 
disease  confined  to  the  transverse  colon  to  manifest  itself  in 
the  form  of  persistent  pain  in  the  lower  intercostal  region. 

The  frequent  occurrence  of  cancer  in  the  mammary  region 
renders  its  detection  one  of  importance  in  its  early  stages, 
while,  in  the  later  stages,  the  pleura  and  the  glands  of  the 
axilla  and  mediastinse  may  be  secondarily  affected  with  can- 
cer tubercles.  Now,  in  these  conditions,  the  presence  of  pain 
in  the  back,  between  the  shoulders,  in  the  side  of  the  chest, 
or  down  the  inner  side  of  the  arm,  may  possibly  afford  invalu- 
able aid  in  diagnosis. 

The  distribution  of  the  sixth  and  seventh  intercostal  nerves 
to  the  skin  over  the  pit  of  the  stomach  may  be  a  useful  fact  to 
remember  in  making  a  diagnosis  of  the  cause  of  pain  in  that 
region,  since,  by  tracing  the  course  of  these  two  nerves  from 
before  backward,  and  observing  the  healthy  or  unhealthy  con- 
dition of  the  structures  near  to  which  the  neiTes  would  pass — 
as  the  pleura,  ribs,  oesophagus,  aorta,  et€. — we  may  at  last 
reach  the  spine  as  the  seat  of  the  disfease  which  is  producing 
pain  in  a  region  far  remote  from  the  cause  to  which  it  is  really 
due.  It  is  by  no  means  uncommon  for  spinal  affections  of  the 
mid-dorsal  region  to  manifest  themselves  by  a  pain  which  is 
distressing,  and  referred  to  the  pit  of  the  stomach  ;  and  such 
an  origin  is  rendered  still  more  probable  if  present  on  both 
sides  of  the  median  line,  since  symmetrical  pains  are  especially 
characteristic  of  central  origin."  Should  such  a  pain  exist,  and 
a  marked  relief  ensue  when  the  patient  is  in  a  recumbent 
posture,  the  probability  of  spinal  origin  is  still  more  distinctly 
suggested. 

'  The  great  splanchnic  nerve  is  connected  above  with  the  fourth,  fifth,  and  sixth  dorsal 
nerves,  and  below  with  the  solar  plexus  and  thence  with  the  stomach,  duodenum,  liver, 
pancreas,  and  intestines.  It  seems  probable,  therefore,  that  the  pain  experienced  in  the 
region  of  the  scapula,  by  patients  afflicted  with  diseases  of  the  digestive  organs,  is  refer- 
able in  some  way  to  the  greater  splanchnic  nerve. 

*  The  reader  is  referred  to  the  general  axioms  of  nerve  distribution,  quoted  on  pages 
645,  646,  and  647  of  this  volume. 


THE  INTERCOSTAL  NERVES.  713 

• 
It  has  been  stated  in  previous  lectures  that  pains  which  are 

confined  to  one  side  of  the  body  are  usually  indicative  of  an 
exciting  cause  which  is  confined  to  the  same  side,  rather  than 
of  diseased  conditions  of  the  central  nerve  ganglia.  It  is 
therefore  customary,  with  those  most  familiar  with  the  steps 
necessary  to  reach*  a  scientific  diagnosis,  to  search  for  sonie 
cause  upon  the  same  side  of  the  body,  in  case  a  pain  exists 
which  is  not  symmetrically  developed  upon  both  sides.  I 
have  known  the  diagnosis  of  aneurism  within  the  thorax  to 
be  discovered  by  a  pain,  which  was  one-sided,  and  which  was 
the  only  symptom  which  the  patient  was  conscious  of,  where 
the  existence  of  the  tumor  would  probably  have  gone  on  un- 
detected but  for  this  valuable  guide.  A  constant  pain  in  the 
back  is  one  of  the  most  positive  signs  of  aneurism  of  the  coeliac 
axis,  and  I  question  if  the  diagnosis  of  aneurism  of  the  abdom- 
inal aorta  in  any  part  of  its  course  should  ever  be  made  unless 
this  symptom  can  be  detected. 

Pain  in  the  region  of  the  pectoral  muscle  may  indicate  some 
cause  referred  either  to  the  tJiird  ov fourth  cervical  ov  the  flrst 
dorsal  nerves ;  hence  we  must  look  in  two  different  localities 
for  the  exciting  lesion.  The  distribution  of  the  cervical  nerves 
to  the  fascia  covering  the  anterior  portion  of  the  chest  is  not 
sufficiently  well  recognized  by  the  profession  at  large,  and 
doubtless  many  cases  have  been  a  source  of  anxiety  to  the 
physician  which  could  have  been  easily  explained,  had  this 
point  been  impressed  upon  them. 

The  distribution  of  the  lower  intercostal  nerves  to  the  in- 
tegument covering  the  upper  part  of  the  muscles  of  the  abdo- 
men may  be  useful  in  diagnosis,  since  pain  in  this  region  of 
the  abdomen  may  be  created  by  pressure  of  fluid  in  the  pleural 
cavities,  and  by  other  lesions  situated  above  the  line  of  the 
diaphragm.  It  is  not  improbable,  therefore,  that  many  cases 
of  this  character  have  misled  the  medical  attendant  who  has 
referred  the  symptom  of  abdominal  pain  to  organs  within  the 
cavity  of  the  abdomen,  when  the  exciting  cause  was  to  be  sought 
for  within  the  chest  or  in  the  course  of  the  lower  intercostal 
nerves  1    Certainly,  successful  treatment  depends  upon  accu- 


714  THE  SPINAL  NERVES. 

racy  in  diagnosis ;  and  the  application  of  the  laws  of  nerve 
distribution  to  fine  discriminations  in  the  appreciation  of 
symptoms  is  a  guide  whose  value  and  utility  are  not  generally 
known. 

When  we  have  our  attention  called  by  a  patient  to  a  pain, 
no  matter  where  its  situation  may  chance  tb  be,  we  are  positive 
that  it  can  be  traced  to  the  nerves  supplying  the  part.  Here, 
then,  we  have  a  direct  guide  to  follow  which  will  usually  lead 
us,  if  we  are  anatomists,  to  the  source  of  the  pain.  As  an  ex- 
ample of  this,  and  they  are  too  numerous  to  mention  in  detail, 
there  is  one  symptom  in  spinal  disease  which  stands  out  prom- 
inently, and  I  might  say  solicits  our  proper  appreciation  of  it, 
and  that  is  a  fixed  and  local  pain  upon  the  surface  of  the  body, 
with  or  without  exacerbations,  and  often  without  any  local  in- 
crease of  temperature  at  the  seat  of  the  disease.  I  feel  quite 
certain  that  through  the  medium  of  this  one  symptom  alone, 
if  properly  employed,  morbid  conditions  of  the  vertebrae  or 
the  spinal  cord,  its  membranes,  and  its  nerves,  may  be  often 
diagnosed  long  before  any  palpable  deformity  of  attitude  or 
gait  exists,  and  a  cure  often  effected  by  simple  rest. 

It  is  in  connection  with  the  nerves  of  the  dorsal  region  that 
pain  is  a  more  valuable  guide  than  in  almost  any  other  portion 
of  the  body.  The  subjacent  viscera,  occupying  the  thoracic 
and  abdominal  cavities,  are  constantly  manifesting  diseased 
conditions  by  pain  of  a  superficial  character  (through  the  in- 
timate communications  which  exist  between  the  splanchnic 
and  dorsal  nerves)  at  spots  often  far  removed  from  the  excit- 
ing cause.  It  is  natural  that  the  medical  attendant,  unless 
his  attention  has  been  directed  to  this  fact,  should  attribute 
the  pain  to  some  fanciful  cause  in  the  locality  of  that  pain,  or 
to  some  general  diagnosis  of  neuralgia,  malaria,  etc.,  when  an 
anatomical  knowledge  might  direct  him  aright  both  in  diag- 
nosis and  treatment.  We  know  that  liver  disease  may  be  oc- 
casionally manifested  by  a  pain  in  the  region  of  the  right 
shoulder ;  that  gastric  and  intestinal  disorders  frequently  pro- 
duce a  constant  pain  in  the  back  between  the  scapulae ;  and 
that  tumors  of  the  viscera  may  produce  like  results  by  press- 


THE  INTERCOSTAL  NERVES, 


Y15 


ure  upon  the  splanclinic  nerves  or  the  solar  plexus  of  which 
they  form  a  part.     Without  such  a  knowledge  and  its  satis- 


FiG.  220. — A  diagram  of  the  regions  of  cutaneous  nerve  distribution  on  the  posterior  sur- 
face of  the  upper  extremity  and  trunk.     (Modified  from  Flower.) 

18,  region  supplied  by  the  second  dorsal  nerve  ;  19,  region  supplied  by  the  suprascapular 
nerve;  20,  region  supplied  by  the  circumflex  nerve  ;  21,  region  supplied  by  the  inter- 
costo-humeral  nerve ;  22,  region  supplied  by  the  external  cutaneous  nerve ;  23,  region 
supplied  by  the  internal  cutaneous  branch  of  the  musculo-spiral  nerve  ;  24,  region 
supplied  by  the  "  nerve  of  Wrisberg  "  ;  25,  region  supplied  by  the  latei'al  branches 
of  the  intercostal  nerves ;  26,  region  supplied  by  the  internal  cutaneous  nerve ;  27,  re- 
gion supplied  by  the  musculo-cutaneou^  nerve ;  28,  region  supplied  by  the  iliac  branch 
of  the  ilio-inguinal  nerve ;  29,  region  supplied  by  the  radial  nerve ;  30,  region  sup- 
plied by  the  ulnar  nerve. 

factory  explanation,  would  we  be  apt  to  refer  such  pain  to 
causes  so  remote  ?    Would  we  look  for  causes  of  abdominal 


716  THE  SPINAL  NERVES. 

pain  in  the  region  of  the  thorax,  without  the  knowledge  that 
the  lower  intercostal  nerves  supplied  the  abdominal  muscles  ? 
The  lessons  taught  by  anatomy  are  of  a  most  practical  char- 
acter, and  worthy  of  the  study  even  of  those  old  in  the  prac- 
tice of  physic.  If  a  patient  complains  of  pain  on  the  surface 
of  the  body,  it  must  be  expressed  by  the  nerve  which  resides 
there ;  there  is  no  other  structure  that  can  express  it,  and 
somewhere  in  its  course  of  distribution,  between  its  periph- 
eral filaments  and  its  central  point  of  origin  from  the  enceph- 
alon  or  the  spinal  cord,  the  precise  cause  of  this  pain  ex- 
pressed upon  the  surface  must  be  situated. 

INTERCOSTAL    KEURALGIA. 

Those  forms  of  neuralgia  which  have  their  seat  in  the 

nerves  which  arise  from  the  dorsal  region  of  the  spinal  cord  j| 

are  grouped  under  the  term  ''dorso-intercostal"  neuralgia,  i 

The  exact  seat  of  the  pain  varies  not  only  with  the  special  i 

nerve  affected,  but  also  with  the  branch  of  the  nerve  which  \ 

seems  to  manifest  the  most  irritation.     Thus,  if  the  upper  \ 
two  nerves  are  involved,  the  pain  may  extend  to  the  arm  as 

well  as  the  trunk;  if  the  posterior  branches  of  the  dorsal  : 

nerves  be  alone  involved,  the  pain  will  be  perceived  in  the  : 
back  and  loins  ;  and,  finally,  if  the  anterior  branches  be  alone 
the  seat  of  pain,  it  will  be  confined  to  the  intercostal  spaces 

and  the  anterior  region  of  the  chest.     It  is  rare  to  find  the  : 

anterior  and  posterior  branches  of  any  dorsal  nerve  simulta-  | 

neously  affected  with  neuralgia.     The  anterior  branches  are'  | 

usually  the  ones  which  suffer,  and  the  pain  assumes  a  type  i 

which  is  properly  called  "intercostal."  ) 

Intercostal  neuralgia  is  more  common  in  women  than  in  j 

men,  and  chiefly  affects  weak,  hysterical,  and  anaemic  sub-  ? 

jects.     It  appears  often  in  those  who  are  convalescing  from  ; 

some  severe  type  of  disease.     The  causes  to  which  this  form  j 

of  neuralgia  can  be  traced  include  exposure  to  cold  or  damp-  | 

ness,  anatomical  changes  in  the  nerves  themselves,  diseases  of  | 

some  of  the  adjoining  organs  (especially  in  connection  with  \ 

phthisis),  embarrassment  to  the  venous  return  of  the  affected  \ 


INTERCOSTAL  NEURALGIA.  717 

region,  dilatation  of  the  venous  plexuses  of  the  interior  of  the 
vertebral  canal,  aortic  aneurisms  (which  lead  to  absorption  of 
the  vertebrae  or  ribs),  all  possible  diseases  of  the  vertebrae 
themselves,  and  also  of  the  ribs,  diseases  of  the  spinal  cord, 
and  malarial  affections. 

This  form  of  neuralgia  is  most  common  upon  the  left  side, 
and  Henle  has  attributed  this  clinical  fact  to  the  arrangement 
of  the  intercostal  veins  of  the  left  side,'  which  relatively  tends 
to  impede  the  return  of  blood  upon  the  left  in  contrast  to  the 
right  side.  From  the  extensive  list  of  causes  which  have  been 
given — and  many  of  the  subdivisions  of  each  have  been 
omitted — it  can  be  readily  understood  that,  to  make  an  accu- 
rate diagnosis  as  to  the  etiology  of  intercostal  neuralgia,  is 
never  possible  without  a  most  thorough  physical  examination 
of  the  subjacent  organs,  the  bones  of  the  thorax,  and  the  con- 
ditions of  the  soft  tissues. 

The  symptoms  of  this  disease  are  generally  confined  to  the 
anterior  and  lateral  walls  of  the  trunk,  more  rarely  to  the 
back  and  the  loins.  The  area  of  the  pain  indicates  the  nerves 
affected,  which  is  often  a  point  of  great  value  in  searching  for 
the  cause.  While  the  pain  is  of  a  burning,  dull,  and  persist- 
ent character  for  the  greater  part,  yet  it  is  often  characterized 
by  paroxysms  of  tearing  and  lancinating  pains  which  follow 
the  course  of  the  nerves  affected  with  a  remarkable  precision. 
The  violence  of  these  paroxysms  may  be  very  great,  so  as  to 
cause  syncope.  All  respiratory  motions,  such  as  sneezing, 
coughing,  blowing  the  nose,  etc.,  increase  the  pain,  and  the 
skin  is  sensitive  to  the  slightest  pressure,  even  the  weight  of 
the  bedclothes  distressing  the  patient,  although  firm  pressure 
may  sometimes  afford  relief.  While  the  paroxysm  is  active, 
the  patients  sit  with  the  body  inclined  toward  the  affected 
side,  and  their  faces  indicate  the  most  extreme  anxiety. 
They  neither  dare  to  speak  loudly  nor  take  a  deep  inspira- 
tion, on  account  of  the  pain  induced  by  such  efforts. 

'  The  intercostal  veins  of  the  left  side  empty  into  the  left  superior  intercostal  vein  or 
the  left  vena  azygos  ;  in  either  case,  the  blood  takes  a  circuitous  route  to  the  superior 
vena  cava 

48 


718  THE  SPINAL  NERVES. 


In  intercostal  neuralgia,  as  in  most  other  forms,  there  are  ; 
certain  points  which  are  particularly  sensitive  to  pressure,  ■ 
and  are  of  great  aid  in  confirming  the  diagnosis.  Thesevj 
points  comprise,  first,  one  near  to  the  vertebral  column  {verte^^A 
hral  point\  where  the  nerve  emerges  from  the  inter-vertebral  - 
foramen  ;  secondly,  one  at  about  the  middle  of  the  entire, 
course  of  the  nerve,  corresponding  to  a  line  dropped  fromji- 
the  center  of  the  axillary  space  {lateral  point\  where  th®j 
lateral  branch  emerges  beneath  the  integument ;  and,  thirdly,  ^ 
one  in  front,  near  to  the  sternal  border  {anterior  or  sternal  ■- 
point\  where  the  anterior  perforating  branch  emerges  be*)! 
neath  the  skin.  \ 

For  some  unknown  reason,  the  intercostal  nerves,  when 
inflamed,  are  particularly  liable   to   be  associated  with  the 
appearance  of  that  form  of  skin  disease  called  "herpes  zos-' 
ter."     This  may  or  may  not  be  accompanied  by  neuralgic^ 
symptoms,  but  it  is  a  valuable  sign  of  a  neuritis  of  the  nerveajl 
supplying  the  region  affected.  ''\ 

The  diagnosis  of  intercostal  neuralgia  can  often  be  made  \ 
only  with  extreme  difficulty.  That  rheumatic  affection  of  | 
the  muscles  of  the  chest  commonly  called  "  pleurodynia"  Ls- 
often  confounded  with  it,  and  the  diagnosis  is  to  be  made  ■ 
chiefly  by  the  absence  of  the  localized  points  of  tenderness  j 
mentioned,  and  the  rapid  disappearance  of  all  symptoms  in;; 
the  course  of  a  few  days,  which  is  seldom  observed  in  true| 
intercostal  neuralgia.  Pleurisy  is  also  to  be  differentiated^ 
from  this  disease  chiefly  by  its  physical  symptoms  ;  and  an-  j 
gina  pectoris  is  to  be  told  by  the  phenomena  presented  by| 
the  heart  and  the  pulse,  as  well  as  by  the  sense  of  impending  | 
death,  threatened  suffocation,  intense  anxiety,  and  the  factj: 
that  the  pain  frequently  shoots  down  the  left  arm.  ' 

NEURALGIA   OF  THE  MAMMARY   GLAND   (mASTODYNIA).  || 

The  skin  over  the  mammary  gland  is  supplied  by  the  an- 
terior and  lateral  branches  of  the  second,  third,  fourth,  fifth, 
and  sixth  intercostal  nerves,  and  by  some  filaments  derived 
from  the  supra-clavicular  nerves,  while  the  glandular  stnict- 


J 


PARALYSIS  OF  THE  DORSAL  NERVES  719 

ure  itself  is  supplied  by  the  lateral  perforating  branches  of 
the  fourth,  fifth,  and  sixth  intercostal  nerves.  This  region  is 
especially  liable  to  an  extreme  form  of  neuralgia,  first  de- 
scribed by  Sir  Astley  Cooper  under  the  name  of  "irritable 
breast."  So  intense  is  tjie  pain  in  some  cases  of  this  affection 
that  it  is  compared  to  the  sensation  of  cutting,  tearing,  or 
stabbing  the  part  with  a  knife.  It  is  usually  paroxysmal  in 
character,  and  generally  of  short  duration,  although  such 
attacks  may  last  for  some  hours. 

This  affection  seems  to  be  associated  with  pregnancy, 
anaemia,  chlorosis,  hysteria,  and  the  development  of  neu- 
romata upon  the  nerves  of  this  region.  It  may  be  persistent 
and  remain  for  years,  and  is  particularly  obstinate  to  treat- 
ment. 

The  detection  of  painful  points  is  to  be  looked  for  in  the 
region  of  the  escape  of  the  nerves  which  supply  the  part  from 
the  inter- vertebral  foramina  ;  and,  in  some  instances,  the  ex- 
istence of  similar  points  may  be  detected  upon  the  breast, 
near  the  nipple,  and  upon  the  sides  of  the  gland.  The  at- 
tacks are  particularly  liable  to  exacerbate  during  the  men- 
strual periods,  and,  during  the  height  of  the  paroxysm,  the 
pain  may  be  transmitted  by  other  nerves  into  the  neck,  down 
the  arm,  and  over  more  extended  areas  upon  the  chest  and 
back. 

PARALYSIS   OF  THE   DORSAL   NERVES. 

The  dorsal  muscles  control,  to  a  great  extent,  the  move- 
ments, fixation,  and  upright  position  of  the  vertebral  column, 
but  these  conditions  require  such  a  complexity  of  muscular 
action  that  it  is  often  difficult,  in  case  of  paralysis,  to  exactly 
decide  as  to  the  muscles  which  are  affected.  Various  degrees 
of  weakness  of  the  dorsal  muscles  are  often  present  in  youth, 
sometimes  on  one  side  and  sometimes  on  the  other,  and  oc- 
casionally affecting  the  whole  back  to  a  greater  or  less  ex- 
tent. 

These  paretic  states  are  dependent  upon  rheumatic  affec- 
tions, diseases  or  injuries  of  the  vertebral  column,  disturb- 
ances of  the  motor  regions  of  the  cerebrum,  lesions  of  the 


720  TEE  SPINAL  NERVES. 

various  ganglia  of  the  encephalon,  and  lesions  of  the  kinesodii 
system  of  the  spinal  cord.     In  paraplegia,  the  motor  paralysis « 
often  extends  upward  to  the  muscles  of  the  trunk ;  while,  i 
in  progressive  muscular  atrophy,  the  muscles  of  the  dorsal! 
region  are  not  infrequently  involved.  ) 

If  the  muscles  of  both  sides  of  the  back  be  paralyzed,  the  | 
spinal  column  gradually  tends  to  assume  the  condition  of  a^ 
posterior  curvature  (paralytic  kyphosis),  and  the  deformity  13  ^ 
usually  most  marked  in  the  dorsal  region,  as  the  lumbar  and  I 
cervical  regions  exhibit  it  to  a  less  degree  on  account  of  their  i 
anatomical  peculiarities.  If  the  extensor  muscles  of  the  back1 
be  markedly  affected,  the  spinal  column  forms  an  equable' 
curve,  as  if  the  body  were  bent  forward  as  in  old  age,  and  thel 
patient  becomes  unable  to  voluntarily  straighten  the  trunk  toj 
its  normal  posture.  When  passive  straightening  is  attempted,  i 
the  spine  is  easily  brought  into  its  proper  curve  ;  and  this  is  ai ; 
point  of  diagnosis  between  paralytic  kyphosis  and  the  de- 
formity dependent  upon  structural  disease  of  the  vertebrae  or  a  * 
state  of  muscular  contracture.  ; 

The  muscles  most  frequently  affected  are  the  sacro-lum-i 
balls  and  the  latissimus  dorsi.  If  they  be  paralyzed  upon  on^ 
side  only,  the  deformity  assumes  the  type  of  scoliosis,  as  a ; 
lateral  curvature  is  produced  by  the  muscles  of  the  unaffected: 
side.  In  this  case,  as  in  the  one  before  cited,  the  patient  is»; 
unable  to  rectify  the  deformity  by  any  voluntary  muscular*' 
effort,  although  the  spinal  curve  can  be  easily  removed  hjl 
mechanical  aid.  I 

When  the  extensor  muscles  of  the  lumbar  region  are| 
markedly  impaired,  the  attitude  assumed  by  the  patient  \&\ 
very  characteristic.      It  consists  of  a  bending  of  the  upper* 
portion  of  the  trunk  in  a  backward  direction,  so  as  to  comrj 
pensate  for  the  bending  forward  of  the  lumbar  vertebrse  ;  t 
bending  of  the  thorax  backward  brings  the  upper  part  of  tb 
body  behind  the  center  of  gravity  of  the  whole  body,  and  the 
balance  is  preserved  exclusively  by  the  action  of  the  muscles 
of  the  abdomen.     When  the  body  is  brought  too  far  forward^ 
it  sinks  and  falls,  as  the  lumbar  muscles  fail  to  support  it 


J 


PARALYSIS  OF  THE  DORSAL  NERVES. 


721 


an  erect  posture.  The  patient  can  not  then  bring  the  trunk 
llnto  its  former  posture  without  the  use  of  the  hands,  which 
•are  employed  in  a  sort  of  a  climbing  process,  the  hands  being 


Fig.  221. —  The  iumbar  plexus.     (Hirschteld.) 

1,  lumbar  and  sacral  portions  of  the  great  sympathetic ;  2,  twelfth  dorsal  pair ;  3,  first 
lumbar  pair;  4,  4',  ilio-hypogastric  branch;  5,  5',  ilio-inguinal  branch;  6,  second 
lumbar  pair ;  7,  origin  of  the  genito-crural  branch  ;  7',  this  same  branch  appearing 
and  descending  in  front  of  the  psoas  muscle ;  8,  origin  of  the  external  cutaneous 
nerve;  8',  this  same  branch  leaving  the  border  of  the  psoas,  and  dividing  at  the 
level  of  the  fold  of  the  groin ;  9,  third  lumbar  pair  ;  10,  fourth  lumbar  pair ;  11,  fifth 
lumbar  pair  ;  12,  lumbo-sacral  trunk  ;  13,  gluteal  branch  of  the  ilio-hypogastric ;  14, 
its  abdominal  branch ;  15,  its  genital  branches ;  16,  external  cutaneous  passing  under 
Poupart's  ligament,  between  the  anterior  superior  and  inferior  spines  of  the  ilium; 
IV,  17,  17,  divisions  of  this  branch;  17',  point  of  origin  of  these  divisions;  18,  18', 
genital  branch  of  the  genito-crural  nerve;  19,  19,  femoral  division  of  this  nerve 
piercing  the  fascia  lata  in  the  neighborhood  of  the  saphenous  opening ;  19',  this 
division  exposed  at  the  fold  of  the  groin,  to  show  its  relations  with  the  femoral  artery 
and  the  saphenous  vein  ;  20,  20',  anterior  crural  nerve  ;  21,  21',  obturator  nerve. 

placed  upon  the  legs  ;  a  series  of  peculiar  movements  of  the 
shoulders  and  trunk  then  follow,  which  are  employed  to  assist 


722  TEE  SPINAL  NERVES. 


% 


the  arms  in  tossing  the  trunk  backward  to  an  extent  sufficient 
to  allow  the  abdominal  muscles  once  more  to  support  it.  This  \ 
difficulty  in  bringing  the  trunk  above  the  level  of  the  loweis '" 
limbs  is  typical  of  this  condition,  but  there  are  still  other  ad|^ 
ditional  points  of  diagnostic  value.  The  lumbar  region  pre- 1 
sents  a  deep  hollow  ;  the  head  is  bent  forward  in  standing  or  ^ 
walking ;  and  the  trunk  may  be  seen  to  have  a  remarkable  ' 
oscillating  movement  when  the  patient  walks.  When  the  i 
patient  sits  down,  the  upper  portion  of  the  body  seems  to' 
sink,  and  the  spine  presents  a  condition  of  kyphosis.  In  fact,  I 
it  seems  hardly  possible  that  the  condition  can  be  mistaken 
by  one  well  versed  in  anatomy. 


THE  LUMBAR  NERVES. 

The  lumbar  nei'ves  comprise  five  pairs  which  escape  from  j 
the  intervertebral  foramina  of  that  region.  Like  all  the  spi-| 
nal  nerves,  they  each  divide,  immediately  after  their  escape,  \ 
into  anterior  and  posterior  divisions,  the  former  of  which  ha|* 
a  larger  proportion  of  motor,  while  the  latter  has  an  excess  oi ' 
sensory  fibers.  These  nerves  are  of  special  interest,  from  the  ; 
fact  that  the  anterior  divisions  of  the  four  upper  nerves  assist  i 
to  form  the  lumbar  plexus.  This  plexus  is  situated  in  the! 
substance  of  the  psoas  muscle,  in  front  of  the  transverse  pro- 1 
cesses  of  the  lumbar  vertebrae.  It  is  narrow  above,  where  it  j 
is  joined  to  the  last  dorsal  nerve,  but  below  it  becomes.^ 
broad,  and  is  connected  with  the  sacral  plexus  by  means  of  j 
the  lumbo-sacral  cord  and  a  filament  from  the  fourth  lumbar  ; 
nerve.  The  table  which  I  now  show  you  will  give  you  an  i 
opportunity  of  contrasting  the  relative  arrangement  of  the^ 
anterior  and  posterior  divisions  of  the  lumbar  nerves,  as  well! 
as  of  studying  the  origin  of  the  seven  main  nerve  trunks^ 
given  off  from  the  lumbar  plexus. 

In  the  following  table  the  formation  of  the  lumbar  pleomi 
is  shown,  as  well  as  the  branches  which  are  given  off  from 
each  nerve  which  assists  to  form  it. 


J 


THE  LUMBAR  NERVES, 


Y23 


TABLE   OF  THE   KEKVES   OF  THE   LUMBAR   REGIOlf. 


Lumbar 

NERVES 


Posterior  divisions. 


1st  Lumbar 
nerve. 


.{ 


Anterior 
divisions 


I 


2d   Lumbar 
nerve. 


3d  Lumbar 
nerve. 


4th  Lumbar 
nerve. 


External 
branches. 


Internal 
branches. 


Filaments  to  erector  spinae  muscle, 
Filaments  to  the  inter-transversales 

muscles, 
Filaments  to  integument  of  back  part 

of  gluteal  region. 
Filaments  to  multifidus  spinas  muscle, 
Filaments  to  integument  near  spinal 

column. 


Lumbar 
Plexus. 


L 


Ilio-hypogastric  nerve,  ^ 
Ilio-inguinal  nerve, 
Communicating  to  2d 

lumbar. 
Genito-crural  nerve, 
External   cutaneous 

nerve,  \ 

Communicating  to  3d 

lumbar. 
Part  of  anterior  crural  1 

nerve, 
Part   of   obturator        |  Given  off  by 


Given  off  by 
the  1st 
lumbar 

NERVE. 

Given  off  by 
the  2d 
lumbar 

NERVE. 


Part  of   accessory  ob- 
turator nerve. 

Communicating  to  4th 
lumbar. 

Part  of  anterior  crural  ^ 
nerve, 

Part   of    obturator 
nerve,  \ 

Part  of  accessory  ob-  I 
turator  nerve,  | 

Lumbo-sacral  cord.        J 


the  3d 
lumbar 

NERVE. 


Given  off  by 
the  4th 
lumbar 

NERVE. 


It  will  be  perceived  that  three  most  important  nerves,  viz., 
the  anterior  crural^  the  obturator^  and  accessory  obturator 
nerves,  are  formed  by  branches  both  of  the  third  and  fourth 
lumbar  nerves,  and  therefore  may  be  said  to  arise  by  two 
heads.  The  accessory  obturator  nerve,  however,  arises  occa- 
sionally by  a  branch  derived  only  from  the  fourth  lumbar 
nerve,  its  other  head  being  a  branch  given  off  from  the  obtu- 
rator nerve. 

The  second  table,  to  which  I  now  call  your  attention,  is 
constructed  to  show  the  distribution  of  each  of  the  seven 
large  branches  of  the  lumbar  plexus.  This  table  may  aid  in 
refreshing  your  memories  while  following  the  subsequent 
lectures,  while  it  also  gives  you,  at  a  glance,  a  better  concep- 
tion of  the  arrangement  of  any  special  nerve  than  a  mere 
verbal  description. 

*  Taken  from  "  The  Essentials  of  Anatomy "  (Darling  and  Ranney).  New  York : 
G.  P.  Putnam's  Sons,  1880. 


724 


THE  SPINAL  NERVES. 


TABLE  OP  THE  DISTEIBUTION  OF  THE  BRANCHES  OF  THE  LUMBAE  PLEXUS.* 


Lumbar 

PLEXUS. 


(1)  Ilio-hypo- 

GASTRIC. 


(2)  Ilio-in- 

GUINAL. 


(3)  Genito- 

CRURAL. 


(4)  External 
cutaneous. 


Iliac  branch.    ■{  Integument  of  gluteal  region. 

h        7       ]  Integument  of  the  hypogastric  region. 

Internal  oblique  muscle, 

Integument  of  upper  and  inner  portion  of  thigh, 

Integument  of  scrotum, 

Integument  of  penis 

Integument  of  labium. 

Genital 


branch 


■I 


Crural  branch 

Anterior  j 

branch.  \ 

Posterior  \ 

branch.  / 


(5)  Anterior 

CRURAL. 


Anterior 

division. 


Posterior 

division. 


(6)  Obtura- 
tor nerve. 


(7)  Accessory 
nerve  .     .    , 


'  Anterior 

branch. 


Posterior 

branch. 


Obturator 


Crcmaster  muscle, 

Scrotum, 

Round  ligament  of  female. 

Integument  of  the  front  and  upper  portion 

of  the  thigh. 
Integument  on  the  anterior  and  outer  as- 
pect of  thigh,  as  low  as  the  knee. 
Integument  of  the  posterior  and  outer  as- 
pect of  the  thigh. 

f  The  sartorius  muscle, 
Middle  cuta-  J  Integument  of  anterior  as- 
neous  nerve.  \      spect  of  thigh,  as  low  as 
the  knee. 

( Integumeiit  of 
External  J      inner     and 
branch.   1      outer   sides 
Internal  cuta-  J  I     of  knee. 

neous  nerve.     |  ^ Integument  oi 

Posterior  J      inner   sides 
branch,    j      of  the  thigh 
(^     and  the  leg. 
Long  or  inter-  ( Integument  of  knee  joint 
nal     saphe-  <      and    front    and    inner 
nous  nerve.    (      sides  of  the  leg  and  foot. 
fAll  the  muscles  on  front 
of  thigh  except  the  ten- 
sor vagince  femoris  and 
the  sartorius. 
Two  in  number.    Distribu- 
ted to  capsule  of  knee 
joint,  and   probably  to 
(^     the  hip  joint. 

To  gracilis. 

To  adductor  longus,' 

To  pectineus, 

To  adductor  brevis. 

With  internal  cutaneous 

nerve. 
With  internal  saphenous  . 

nerve. 


Muscular 

branches. 


Articular 
branches. 


Muscular 

branches. 


Anastomotic 
branches. 


M 


Articular 

branches. 
Muscular 

branches. 
Muscular 

branch. 
Articular 

branches. 
Cutaneous         \  To    the    integument    of 


j  To  knee  joint. 

j  Obturator  externus, 
I  Adductor  magnus. 

<  To  pectineus. 
\  To  hi^  joint. 


m 


branches.  (      thigh  and  leg. 


'  Taken  from  "  The  Essentials  of  Anatomy  "  (Darling  and  Ranney). 
P.  Putnam's  Sons,  1880. 


New  York :  G* 


BRANCHES  OF  THE  LUMBAR  PLEXUS.  725 

THE  ILIO-HYPOGASTRIC   NERVE. 

This  nerve  is  named,  from  its  two  terminal  filaments  of 
distribution,  the  iliac  and  hypogastric  branch.  It  is  given  off 
by  the  first  lumbar  nerve  in  company  with  the  ilio-inguinal. 
It  emerges  from  the  outer  border  of  the  psoas  muscle,  crosses 
the  quadratus  lumborum,  then  perforates  the  transversalis 
muscle  of  the  abdomen,  and  finally  divides  between  it  and 
the  internal  oblique  muscle  into  its  iliac  and  hypogastric 
branches. 

The  iliac  branch  pierces  the  internal  and  external  oblique 
muscles  just  above  the  crest  of  the  ilium,  and  supplies  the 
skin  of  the  gluteal  region,  while  the  Jiypogastric  branch 
pierces  the  internal  oblique  and  the  aponeurosis  of  the  ex- 
ternal oblique  muscle  a  little  above  the  external  abdominal 
ring,  and  supplies  the  skin  of  the  hypogastrium.  In  some 
cases  the  ilio-inguinal  nerve  is  incompletely  developed,  and 
this  nerve  may  then  be  traced  downward  to  the  skin  of  the 
penis,  scrotum,  labium,  and  thigh. 

THE  ILIO-IKGUIN^AL  NERVE. 

This  nerve  arises,  in  common  with  the  preceding  nerve, 
from  the  first  lumbar  nerve,  but  it  is  smaller  in  point  of  size 
than  its  fellow.  Like  the  ilio-hypogastric,  it  pierces  the  outer 
border  of  the  psoas,  and  crosses  the  quadratus  lumborum 
muscle,  lying  below  the  preceding  nerve ;  it  then  pierces  the 
transversalis  muscle,  enters  the  inguinal  canal,  passes  through- 
out the  entire  length  of  that  canal  in  front  of  the  spermatic 
cord,  and  supplies  the  skin  of  the  penis,  scrotum,  labium, 
and  of  the  upper  and  inner  portions  of  the  thigh.  It  is  some- 
times incompletely  developed,  in  which  case  the  ilio-hypogas- 
tric nerve  takes  its  place. 

CLINICAL   POINTS   PERTAINING  TO   THE   ILIO-HTPOGASTRIC   AND  ILIO- 
INGUINAL   NERVES. 

These  two  nerves  are  sometimes  the  seat  of  a  severe  form 
of  neuralgia.     It  may  be  produced  by  disease  of  the  lumbar 


726  TEE  SPINAL  NERVES. 

vertebrae,  structural  changes  in  the  parts  investing  the  lum- 
bar plexus,  pelvic  diseases,  exudations  in  the  substance  of 
the  psoas  muscle,  strains,  contusions,  exposure,  and  an  hys- 
terical condition.  The  pains  are  usually  of  a  paroxysmal 
character,  and  radiate  in  the  course  of  these  nerves  ;  they  are 
of  a  lancinating  type,  and  often  extremely  severe.  Painful 
points  may  be  detected  in  one  of  the  following  regions,  or 
possibly  in  all  of  them  :  1,  a  lumbar  pointy  near  the  spinous 
processes  of  the  lumbar  vertebrae  ;  2,  an  iliac  pointy  near  to 
the  middle  of  the  crest  of  the  ilium,  where  the  ilio-hypogas- 
tric  nerve  pierces  the  transversalis  muscle  ;  3,  an  hypogastric 
pointy  slightly  above  the  external  ring,  where  the  ilio-hypo- 
gastric  nerve  pierces  the  aponeurosis  of  the  external  oblique 
muscle  ;  4,  an  inguinal  point ;  and  5,  points  upon  the  scrotum 
or  labium.  It  is  stated  by  Notta '  that  this  type  of  neuralgia 
may  be  occasionally  accompanied  by  an  increase  in  the  sexual 
appetite,  and  a  spasmodic  contraction  of  the  cremaster  muscle. 

This  form  of  neuralgia  is  to  be  diagnosed  from  rheumatic 
myalgia  of  the  longissimus  dorsi  and  sacro-lumbalis  muscles, 
and  from  those  types  of  chronic  affections  of  the  uterus  which 
induce  pain  in  the  back.  It  might  also  be  possibly  mistaken 
for  an  attack  of  renal  or  biliary  colic.  The  diagnosis  will  be 
made  chiefly  by  the  "puncta  dolorosa  " '  previously  described, 
by  the  course  of  the  pain,  and  by  its  intense  paroxysmal  and 
lancinating  character. 

The  nerves  which  are  distributed  to  the  skin  of  the  ab- 
dominal walls  may  be  considered  as  comprising  two  distinct 
sets,  based  on  the  physiological  action  of  the  abdominal  mus- 
cles which  are  supplied  by  them.  According  to  Hilton,  the 
abdomen  may  be  divided,  on  a  line  corresponding  with  the 
situation  of  the  umbilicus,  into  an  upper  or  respiratory  por- 
tion, and  a  lower  or  abdominal  portion.  The  upper  or  respi- 
ratory portion  is  supplied,  in  great  part,  by  the  lower  inter- 
costal nerves,  which  are  distributed  also  to  the  muscles  of  the 


'  As  quoted  by  Erb. 

*  A  name  applied  by  Valleix  to  the  spots  of  extreme  local  tenderness  found  along  the 
course  of  a  nerve  which  is  the  seat  of  neuralgia. 


THE  EXTERNAL   CUTANEOUS  NERVE.  727 

chest,  and  whicli,  if  taken  with  the  other  intercostal  nerves 
as  a  group,  are  essentially  respiratory  in  their  function.  The 
lower  or  abdominal  portion  of  the  abdomen  is  supplied  chiefly 
by  the  ilio-hypogastric  nerve,  although  the  ilio-inguinal,  the 
genito-crural,  and  the  posterior  branches  of  the  lumbar  nerves 
assist  in  furnishing  motor  power  to  the  muscles  of  that  region. 
The  subjacent  peritonaeum  is  unquestionably  supplied  from 
the  same  sources  of  nerve  power  as  the  muscles  and  skin  of 
the  individual  regions  of  the  abdomen,  and  it  is  considered 
probable  by  the  author  above  quoted  that  the  spinal  nerves 
which  are  distributed  to  the  skin,  muscles,  and  parietal  peri- 
tonaeum may  be  also  associated  with  the  visceral  layer  under- 
neath, by  means  of  communications  with  the  sympathetic 
nerve.  The  abdominal  muscles  unquestionably  assist  the  co- 
lon in  its  endeavors  to  force  the  faeces,  by  its  peristaltic  action 
alone,  throughout  its  length,  since  the  force  of  gravity  has 
to  be  overcome  in  its  ascending  portion,  and  the  curves  of  the 
sigmoid  flexure  in  its  terminal  portion.  It  would  therefore 
be  an  additional  confirmation  of  a  general  law  of  nerve  dis- 
tribution, provided  the  distribution  of  the  abdominal  nerves 
to  the  intestinal  covering  of  peritonaeum  could  be  fully  veri- 
fied ;  since  the  structures  which  assist  in  moving  the  adjacent 
organs — the  abdominal  muscles — would  be  supplied  from  the 
same  source  as  the  parts  moved,  as  well  as  the  skin  over  those 
muscles. 

THE   EXTERI^AL   CUTANEOUS   KERVE. 

This  nerve  arises  from  the  trunk  of  the  second  lumbar 
nerve,  in  common  with  the  genito-crural,  but  it  usually  re- 
ceives a  few  filaments  from  the  third  lumbar.  It  pierces  the 
psoas  muscle,  near  to  its  central  point,  and  crosses  the  iliacus 
muscle  in  order  to  reach  a  notch  below  the  anterior  superior 
spine  of  the  ilium,  where  it  escapes  below  Poupart's  ligament. 

The  anterior  branch  of  this  nerve  pierces  the  fascia  lata  at 
about  four  inches  below  Poupart's  ligament,  and  supplies  the 
integument  of  the  anterior  and  outer  aspects  of  the  thigh, 
while  the  posterior  branch  supplies  the  integument  of  the 
outer  and  posterior  aspects  of  the  same  region.    Both  of  these 


728 


THE  SPINAL  NERVES. 


terminal  branches  are  given  off  after  the  main  nerve  trunk  has 
escaped  from  beneath  Poupart'  s  ligament.  It  will  be  observed 
that  this  nerve  pierces  the  psoas  muscle  in  a  different  direc- 


Fio.  222.— 77ic  cuia^ 


,c.>  ccs  of  the  Ihiffh.     (lli.c?vii.c.J.) 


1,  lumbar  and  sacral  portions  of  the  great  sympathetic;  2,  twelfth  dorsal  pair;  3,  first 
lumbar  pair;  4,  4',  ilio-hypogastric  branch;  5,  5',  ilio-inguinal  branch;  6,  second 
lumbar  pair;  7,  origin  of  the  genito-crural  branch  ;  7',  this  same  branch  appearing 
and  descending  in  front  of  the  psoas  muscle ;  8,  origin  of  the  external  cutaneous 
nerve ;  8',  this  same  branch  leaving  the  border  of  the  psoas,  and  dividing  at  the 
level  of  the  fold  of  the  groin ;  9,  third  lumbar  pair  ;  10,  fourth  lumbar  pair ;  11,  fifth 
lumbar  pair  ;  12,  lumbo-sacral  trunk  ;  13,  gluteal  branch  of  the  ilio  hypogastric ;  14, 
its  abdominal  branch;  15,  its  genital  branches;  16,  external  cutaneous  nei-ve  passing 
under  Poupart's  ligament,  between  the  anterior  superior  and  inferior  spines  of  the 
ilium ;  17,  17, 17,  divisions  of  this  branch ;  17',  point  of  origin  of  these  divisions  ;  18, 
18',  genital  branch  of  the  genito-crural  nerve;  19,  19,  femoral  division  of  this  nerve 
piercing  the  fascia  lata  in  the  neighborhood  of  the  saphenous  opening ;  19',  this 
division  exposed  at  the  fold  of  the  groin,  to  show  its  relations  with  the  femoral  artery 
and  the  saphenous  vein  ;  20,  20',  anterior  crural  nerve  ;  21,  21',  obturator  nerve. 


tion  from  the  two  preceding  nerves,  and  that  it  crosses  over 
the  iliacus  muscle,  while  the  two  preceding  nerves  crossed  the 


THE  aENITO-CRTJEAL  NERVE.  729 

quadratus  lumborum.  This  fact,  which  is  true  also  of  the 
genito-crnral  nerve,  is  to  be  remembered  in  tracing  the  seat  of 
origin  of  a  pain  felt  in  the  regions  supplied  by  either  of  these 
nerves.  We  would  naturally  look,  as  we  pass  toward  the 
trunk,  either  to  find  the  cause  of  such  a  pain  (manifested  by 
the  external  cutaneous  nerve)  in  the  region  of  Poupart's  liga- 
ment, or  to  detect  some  pelvic  cause  involving  the  iliacus 
muscle,  some  abnormal  condition  of  the  psoas  muscle,  or  some 
lesion  of  the  vertebrae  in  the  lumbar  region. 

THE   GENITO-CKUEAL    NERVE. 

This  nerve  arises,  in  common  with  the  external  cutaneous, 
from  the  second  lumbar  nerve,  although  it  occasionally  receives 
some  filaments  from  the  first  lumbar.  It  pierces  the  psoas 
muscle,  and  divides  into  its  two  terminal  branches  upon  its 
anterior  surface. 

The  genital  branch  crosses  the  external  iliac  artery  and 
passes  through  the  inguinal  canal  to  supply  the  cremaster 
muscle  and  the  scrotum  or  labium ;  it  lies  behind  the  sper- 
matic cord  in  the  male  and  the  round  ligament  in  the  female. 

The  crural  branch  pierces  the  fascia  lata  (after  escaping 
beneath  Poupart's  ligament  on  the  inner  side  of  the  psoas 
muscle)  on  the  outer  side  of  the  femoral  vessels,  and  supplies 
the  skin  of  the  upper  and  anterior  part  of  the  thigh,  anasto- 
mosing with  the  middle  cutaneous  branch  of  the  anterior 
crural  nerve. 

CLINICAL    POINTS    PERTAINING  TO    THE    EXTERNAL    CUTANEOUS   AND 
GENITO-CRURAL   NERVES. 

As  both  of  these  nerves  are  distributed  chiefly  to  the  integ- 
ument, a  knowledge  of  their  anatomy  affords  the  intelligent 
practitioner  a  means  of  tracing  the  situation  of  any  local  cause 
of  a  pain,  confined  to  the  regions  which  these  nerves  supply. 
While  their  course  is  such  as  to  render  them  less  liable  to 
local  pressure  or  injury  than  the  obturator  or  anterior  crural 
nerves,  and  while  the  fact  that  they  are  distributed  to  no 
muscles  (excepting  the  cremaster)  deprives  them  of  much  of 


730  THE  SPINAL  NERVES. 


d 


the  physiological  interest  which  other  nerves  possess,  still  it 
is  possible  to  imagine  certain  localized  conditions  of  the  psoas 
and  iliacus  muscles,  local  swellings  in  the  vicinity  of  Pou- 
part's  ligament,  and  possible  forms  of  vertebral  disease  which 
might  be  manifested  exclusively  through  the  medium  of  these 
nerves. 

THE  ANTERIOR  CRURAL  NERVE. 

This  is  the  largest  branch  of  the  lumbar  plexus.  It  arises 
mainly  from  the  third  and  fourth  lumbar  nerves,  but  often 
receives  a  fasciculus  from  the  second.  In  its  course,  it  per- 
forates the  psoas  muscle,  emerging  from  it  at  the  lower  part 
of  its  outer  border.  It  then  passes  between  the  psoas  and 
iliacus  muscles,  and  enters  the  thigh  by  escaping  under  Pou- 
part's  ligament  about  one  half  inch  to  the  outer  side  of  the 
femoral  artery.  Its  main  divisions  (the  middle  and  internal 
cutaneous  and  long  saphenous  nerves)  are  given  off  after  it 
enters  the  thigh.  The  distribution  of  each  of  these  terminal 
branches  is  shown  you  upon  the  table,'  but  I  would  call  your 
attention  to  some  points  of  special  interest  pertaining  to  the 
anterior  crural  nerve,  which  will  perhaps  enable  you  to  ap- 
preciate the  value  which  some  portions  of  this  table  pos- 
sess. 

The  anterior  crural  nerve  supplies  nearly  all  of  those  mus- 
cles which  are  employed  in  the  first  effort  of  progression. 
As  the  act  of  taking  a  step  forward  is  performed,  we  flex  the 
thigh  upon  the  pelvis,  we  extend  the  leg  at  the  knee,  and  we 
slightly  evert  the  foot."  Now,  all  the  muscles  which  aid  us 
in  performing  these  various  movements — the  psoas  and  ilia- 
cus, the  pectineus  and  sartorius,  the  four  muscles  of  the 
quadriceps  extensor,  and  the  subcrureus — are  supplied  by  the 
anterior  crural  nerve.  This  nerve  also  sends  branches  both  to 
the  knee  joint  and  hip  joint ;  the  capsular  ligament  of  the 
former,  as  well  as  that  of  the  latter,'  being  supplied  by  fila- 
ments which  can  easily  be  demonstrated  by  dissection.     If  we 

'  Sec  page  724  of  this  volume.  '  John  Hilton,  op.  cit. 

^  This  fact  is  not  so  stated  by  all  of  the  text-books  upon  descriptive  anatomy,  but, 
nevertheless,  I  regard  it  as  capable  of  demonstration. 


THE  ANTERIOR   CRURAL  NERVE. 


Y31 


now  consider,  in  the  third  place,  that  the  cutaneous  branches 
of  this  nerve  supply  the  skin  of  the  thigh,  and  also  the  re- 
gions over  the  two  Joints  mentioned,  we  are  enabled  to  again 


Fig.  223. —  The  muscular  branches  of  the  anterior  and  internal  portions  of  the  thigh. 

(Sappcy.) 

1,  anterior  crural  nerve  ;  2,  branch  which  it  furnishes  to  the  iliacus  muscle  ;  3,  twig  which 
it  sends  to  the  internal  portion  of  the  psoas  muscle  :  4,  middle  cutaneous  branch  of 
the  anterior  crural,  whose  three  branches  have  been  divided  close  to  their  origin  in 
order  to  show  the  branches  to  the  quadriceps  extensor  and  the  internal  saphenous 
nerve,  which  are  more  deeply  placed  ;  5  and  6,  muscular  filaments  of  the  internal 
cutaneous  nerve  ;  7,  origin  of  the  cutaneous  branches  which  pierce  the  fascia  lata  at 
the  level  of  the  saphenous  opening ;  8,  deep  or  anastomotic  filament  of  the  internal 
cutaneous  branch  of  the  anterior  crural ;  9,  branches  to  the  rectus  muscle  ;  10, 
branches  to  the  vastus  externus  ;  11,  branches  to  the  vastus  internus;  12,  12,  inter- 
nal saphenous  nerve  ;  13,  patellar  branch  of  this  nerve  ;  14,  its  vertical  or  tibial 
branch;  15,  obturator  nerve  ;  16,  branch  which  it  furnishes  to  the  adductor  longus; 
17,  branch  to  the  adductor  brevis;  18,  branch  to  the  gracilis  ;  19,  branch  to  the  ad- 
ductor magnus  ;  20,  lumbo-sacral  trunk  ;  21,  junction  of  this  nerve  with  the  first 
sacral  nerve ;  22,  22,  lumbar  and  sacral  portions  of  the  sympathetic ;  23,  external 
cutaneous  nerve. 


732 


THE  SPINAL  NERVES. 


8  I 


10 


13- 


12 


1^ 

Fig.  224. — A  diagram  of  the  cutaneous  supply  of  the  ayiterior  aspect  of  the  lower  extremity. 

1,  region  supplied  by  the  lateral  branches  of  the  intercostal  nerves  ;  2,  region  supplied  by 
the  anterior  branches  of  the  intercostal  nerves;  3,  region  supplied  by  the  ilio-hypo- 
gastric  nerve ;  4,  region  supplied  by  the  ilio-inguinal  nerve  ;  5,  region  supplied  by 
the  genito-crural  nerve ;  6,  region  supplied  by  the  middle  cutaneous  branch  of  the 
anterior  crural  nerve ;  7,  region  supplied  by  the  internal  cutaneous  branch  of  the 
anterior  crural  nerve  and  partly  by  the  obturator  nerve ;  8,  region  supplied  by  the 
external  cutaneous  nerve ;  9,  region  supplied  by  the  long  saphenous  branch  of  the 
anterior  crural  nerve  ;  10,  region  supplied  by  the  branches  of  the  external  popliteal 
nerve;  11,  region  supplied  by  the  musculo  cutaneous  nerve  ;  12,  region  supplied  by 
the  terminal  filaments  of  the  musculo-cutaneous  nerve;  13,  region  supplied  by  the 
external  saphenous  nerve ;  14,  region  supplied  by  the  anterior  tibial  nerve. 


CLINICAL  POINTS  OF  ANTERIOR   CRURAL  NERVE.     733 

record  a  confirmation  of  that  axiom  of  Hilton/  that  a  nerve 
which  supplies  a  joint  must  supply  also  muscles  which  move 
that  joint,  and  the  skin  over  the  insertion  of  those  muscles. 
The  long  saphenous  nerve  seems,  at  first  sight,  to  extend  far 
beyond  the  limits  of  the  muscular  distribution  of  the  anterior 
crural,  but,  when  we  look  closely  into  the  anatomical  rela- 
tions of  the  fascia  of  the  leg,  we  find  that  the  muscles  sup- 
plied by  the  anterior  crural  nerve  are  attached  to  it,  especially 
the  sartorius,  whose  insertion  into  this  fascia  is  as  intimate 
as  that  of  the  biceps  into  the  fascia  of  the  forearm  ;  and 
we  also  notice  that  the  cutaneous  distribution  over  this 
fascia  is  derived  from  the  same  sources  as  are  the  muscles 
which  are  attached  to  it.  This  fact  is  in  perfect  accord  with 
the  axiom  given  in  a  previous  lecture,  viz.,  that  a  fascia,  to 
which  muscles  are  attached,  must  be  considered  as  one  of  the 
points  of  insertion  of  the  muscles  connected  with  it,  and  that 
the  cutaneous  distribution  over  such  a  fascia  will  be  found  to 
be  derived  from  the  nerves  which  supply  those  muscles.  We 
thus  discover  in  the  lower  extremity  the  same  general  laws 
of  nerve  distribution,  as  were  verified  in  connection  with  the 
upper  extremity,  fully  carried  out ;  and  it  is  thus  that  many 
of  the  apparent  deviations  from  the  natural  order  of  nerve 
supply  may  be  explained  by,  and  often  act  as  guides  to,  the 
presence  of  some  anatomical  fact,  whose  physiological  impor- 
tance had  either  not  been  recognized  or  properly  appre- 
ciated. 

CLINICAL   POINTS   PERTAINING  TO   THE   ANTERIOR   CRURAL  NERVE. 

The  relation  of  this  nerve  to  the  femoral  artery  as  it  passes 
underneath  Poupart's  ligament  and  its  still  more  intimate  re- 
lation with  that  vessel  in  Scarpa's  space  render  it  of  special 
interest  to  the  surgeon.  Its  internal  cutaneous  branches 
cross  the  upper  part  of  the  femoral  artery  in  that  space,  be- 
fore it  becomes  properly  a  cutaneous  nerve ;  while  the  long 
saphenous  nerve  lies  to  the  outer  side  of  that  vessel  for  nearly 
its  entire  length,  being  at  first  slightly  removed  from  it,  but 

49  ^  Op.  cit. 


734  THE  SPINAL  NERVES. 

approaching  it  more  closely  in  the  lower  part  of  its  course. 
This  latter  nerve  also  bears  an  intimate  relation  with  the  in- 
ternal saphenous  vein  for  the  greater  portion  of  its  course ; 
hence  the  pain  experienced  from  varicose  veins  in  this  region. ' 

It  is  customary  with  surgeons  to  regard  a  pain  which  is 
localized  at  the  iniier  side  of  the  knee  (since  the  obturator 
nerve  is  distributed  to  that  region)  as  strongly  diagnostic  of 
disease  of  the  hip  joint,  because  that  nerve  is  supposed  to  have 
an  iijtimate  connection  with  the  internal  structures  of  the  hip. 
So  strongly  is  this  impression  grounded  in  the  minds  of  some 
of  our  prominent  surgical  authors  that  the  presence  of  pain 
in  any  other  locality  than  that  just  mentioned  is  not  con- 
sidered as  particularly  indicative  of  morbus  coxarius ;  and 
the  inference  is  certainly  implied,  if  not  directly  stated,  that 
the  accuracy  of  diagnosis  of  this  condition  can  be  questioned 
if  this  symptom  be  not  confined  to  the  region  supplied  by  the 
obturator  nerve.  I  am  not  prepared  to  admit  that  pain  in  the 
knee  is  always  present  in  morbus  coxarius,  nor  am  I  inclined 
to  think  that  the  anterior  crural  nerve,  from  its  distribution 
to  the  capsular  ligament  of  the  hip  joint,  can  not  also  be  one 
of  the  sources  of  sympathetic  pains  referred  to  the  knee,  in 
case  the  hip  be  diseased.  I  admit  that  the  obturator  nerve, 
from  its  distribution  to  the  internal  structures  of  the  hip  joint,' 
is  the  most  frequent  source  of  transmission  of  these  sympa- 
thetic pains ;  but  the  sciatic  and  anterior  crural  nerves  may 
also  indicate  an  irritation  of  their  filaments  to  the  capsule  of 
the  hip  by  pains  referred  to  the  other  regions  which  they 
supply. 

Spasm  of  the  quadriceps  extensor  muscle,  which  is  sup- 
plied by  the  anterior  crural  nerve,  is  often  observed  in  artic- 
ular neuralgia  of  the  knee  joint;  while  the  rigid  extension 
of  the  leg  upon  the  thigh,  met  with  in  tetanus,  is  dependent 
upon  irritation  of  this  nerve.     In  his  treatise  upon  nervous 

^  Varicose  veins  are  most  common  on  the  inner  side  of  the  leg.  The  pain  of  these 
tumors  may  often  be  arrested  by  simple  elevation  of  the  foot,  since  the  excess  of  blood 
in  the  part  is  thus  relieved. 

'  It  is  claimed  by  Hilton  that  this  nerve  is  distributed  chiefly  to  the  ligamentum  teres, 
and  that  this  accounts  for  it  being  so  frequently  affected  by  disease  of  the  hip  joint. 


PARALYSIS  OF  ANTERIOR   CRURAL  NERVE. 


735 


diseases,  Eulenberg  reports  a  case  of 
clonic  spasm  localized  in  the  quadri- 
ceps extensor  muscle  whicli  was  in- 
duced whenever  an  attempt  to  walk 
or  stand  w^as  made,  but  such  cases  are 
of  rare  occurrence. 

Paralysis  confined  to  the  anterior 
crural  nerve  i^  not  of  common  occur- 
rence, but  is  still  observed  as  a  result 
of  injuries  to  the  vertebral  column  and 
pelvis,  from  tumors  and  extravasa- 
tions of  blood  in  the  region  of  the 
Cauda  equina,  and  as  a  sequel  to  a 
severe  type  of  inflammation  of  the 
knee  joint.  It  has  been  known  to  oc- 
cur in  connection  with  psoas  abscess 
and  simple  inflammation  of  the  psoas 
muscle ;  while  fractures  of  the  thigh, 
cuts,  stab  wounds,  neuritis,  pelvic  tu- 
mors, and  tumors  of  the  thigh,  have 
been  reported  as  inducing  this  type  of 
paralysis.  Finally,  it  is  a  frequent 
symptom  of  spinal  paralysis  in  all  of 
its  forms,  and,  more  rarely,  of  cere- 
bral paralysis  and  of  progressive  mus- 
cular atrophy. 

From  what  has  been  already  said 
as  to  the  distribution  of  this  nerve  to 
muscles,  it  is  easy  to  understand  that 
the  symptoms  of  this  type  of  paralysis 
will  be  confined  to  the  inability  of  the 
anterior  thigh  muscles  to  perform 
their  accustomed  functions.  Such  pa- 
tients can  not  flex  the  leg  at  the  hip 
joint  or  raise  the  body  from  the  re- 
cumbent position;  neither  are  they 
able  to  extend  it  nor  to  move  the  leg 


Fig.  225. — Cutaneous  nerves  of 
the  anterior  /)«r^  of  the 
thigh.     (Sappey.) 

1,  external  cutaneous  branch  of 
the  lumbar  plexus  ;  2,  2, 
external  cutaneous  or  su- 
perior perforating  branch  of 
the  anterior  crural  nerve ; 
3,  3,  middle  cutaneous  or 
inferior  perforating  branch 
of  this  nerve;  4,  filament 
furnished  by  this  branch 
to  the  scrotum  ;  5,  internal 
cutaneous  branch  of  the 
anterior  crural  nerve ;  6, 
superficial  division  of  this 
branch ;  Y,  deep  division  of 
the  same  ;  8,  superficial  di- 
vision of  the  small  musculo- 
cutaneous branch  of  the  an- 
terior crural ;  9,  transverse 
or  patellar  branch  of  the 
internal  saphenous  nerve ; 
10,  internal,  vertical,  or  tib- 
ial branch  of  the  same. 


736  THE  SPINAL  NERVES. 

and  foot  forward  when  sitting.  For  this  reason  standing  and 
walking  are  rendered  very  insecure,  and  such  acts  as  running, 
jumping,  etc.,  are  often  impossible  with  patients  so  afflicted. 
The  regions  of  the  skin  which  are  supplied  by  the  anterior  cru- 
ral nerve  may  manifest  disturbances  of  sensibility.  If  the  scro- 
tum, labium,  hypogastrium,  or  inguinal  regions  exhibit  the 
same  disturbances  of  sensibility,  the  seat  of  the  paralysis  is 
positively  indicated  as  being  above  the  origin  of  the  branches 
of  the  two  upper  lumbar  nerves  (ilio-hypogastric,  ilio-ingui- 
nal,  genito-crural,  and  external  cutaneous  nerves).  Among 
the  evidences  of  disturbed  sensibility  which  you  may  be  called 
upon  to  recognize  may  be  mentioned  the  conditions  of  anaes- 
thesia, hyperesthesia,  the  sensations  of  furriness,  numbness, 
and  chilliness. 

Atrophy  of  the  muscles  supplied  by  the  anterior  crural 
nerve  may  follow  such  paralysis.  This  is  generally  so  well 
defined  as  to  be  apparent  to  the  naked  eye  when  the  two 
thighs  are  compared  ;  but  it  may,  occasionally,  be  so  slight  as 
to  require  careful  measurement  of  the  thighs.  In  some  cases, 
certain  muscles  exhibit  this  atrophy  more  than  others  of  the 
group,  and  even  parts  of  muscles  may  appear  flaccid,  relaxed, 
and  shrunken,  while  others  preserve  their  normal  appearance. 

Crural  neuralgia  may  be  manifested  by  paroxysms  of 
pain  upon  the  anterior  and  inner  surfaces  of  the  thigh  and 
leg.  It  may  affect  the  inner  border  of  the  dorsal  surface  of 
the  foot  and  large  toe.  It  is  less  frequent  than  neuralgia  of 
the  sciatic  nerve,  which  affects  the  back  of  the  leg  and  plantar 
region  of  the  foot.  This  diseased  condition  may  result  from 
compression  of  the  lumbar  plexus,  from  degeneration  of  neigh- 
boring lymphatic  glands,  exudations  upon  or  in  the  substance 
of  the  psoas  muscle,  aneurism  of  the  iliac  arteries,  strangu- 
lated hernia  of  the  femoral  region,  dislocations  at  the  hip 
joint,  traumatism,  exposure  to  cold  or  dampness,  coxalgia, 
etc.  The  diagnostic  points  of  tenderness  are  detected  as  fol- 
lows :  1,  a  crural  point,  at  the  exit  of  the  nerve  below  Pou- 
part'  s  ligament ;  2,  an  anterior  femoral  point,  at  the  place 
of  exit  of  the  saphenous  nerve  through  the  fascia  lata ;  3,  an 


CUTANEOUS  NERVES   OF  LOWER  EXTREMITY.         T3T 


16 


\      15 


\  17  \ 


Id 


■    20 


21 


i    2Z 


I  / 


Fig.  226. — A  diagram  of  the  cutaneous  supply  of  the  posterior  aspect  of  the  lower  extremities. 

15,  region  supplied  by  the  lateral  branches  of  the  intercostal  nerves;  16,  region  supplied 
by  the  posterior  branches  of  the  lumbar  nerves ;  1*7,  region  supplied  by  the  iliac 
branch  of  the  iliohypogastric  nerve;  18,  region  supplied  by  the  pudic  nerve;  19, 
region  supplied  by  the  inferior  gluteal  branch  of  the  small  sciatic  nerve ;  20,  region 
supplied  by  the  external  cutaneous  nerve ;  21,  region  supplied  by  the  internal  cuta- 
neous branch  of  the  anterior  crural  nerve  ;  22,  region  supplied  by  the  small  and 
great  sciatic  nerves  ;  23,  region  supplied  by  branches  from  the  external  popliteal 
nerve ;  24,  region  supplied  by  the  external  saphenous  nerve  ;  25,  region  supplied  by 
the  posterior  tibial  nerve. 


738  TEE  SPIKAL  NERVES. 

articular  point,  at  the  inner  side  of  the  knee  joint,  where 
the  nerve  divides ;  4,  a  plantar  pointy  on  the  inner  side  of 
the  foot ;  and,  finally,  5,  a  digital  pointy  over  the  tuberosity 
of  the  big  toe. 

Spasm  of  the  muscles  of  the  hip,  supplied  by  the  anterior 
crural  nerve  (the  spasmodic  contracture  of  Stromeyer),  may 
occur  from  any  of  the  causes  of  crural  paralysis  previously 
mentioned.  The  thigh  is  then  flexed,  the  pelvis  raised  up  on 
the  affected  side,  and  the  limb  shortened  and  made  rigid. 

THE  OBTURATOR   KERVE. 

This  nerve  arises  mainly  from  the  third  and  fourth  lumbar 
nerves,  but  it  often  receives  a  fasciculus  from  the  second.  It 
descends  in  the  innermost  fibers  of  the  psoas  muscle,  as  far  as 
the  level  of  the  brim  of  the  pelvis,  when  it  escapes  from  the 
inner  border  of  that  muscle,  crosses  the  sacro-iliac  articula- 
tion, accompanies  the  obturator  vessels  along  the  outer  wall 
pf  the  pelvis  lying  slightly  above  them,  and  passes  into  the 
thigh  through  the  upper  part  of  the  obturator  foramen. 

The  table,'  previously  referred  to,  will  enable  you  to  grasp 
the  details  of  the  subdivisions  of  this  nerve,  and  the  distribu- 
tion of  each  branch  ;  but  it  fails  to  point  out  some  important 
facts  pertaining  to  this  nerve,  which  help  to  explain  its  physi- 
ological attributes  and  to  elucidate  its  clinical  bearings. 

In  the  first  place,  we  can  see  by  this  table  that  the  obtu- 
rator nerve  sends  filaments  to  the  hip  joint  and  the  knee 
joint.  To  the  former  articulation  two  filaments  of  this  nerve 
can  be  traced,  one  given  off  to  the  capsular  ligament,  as  the 
nerve  passes  through  the  obturator  foramen,  the  other  given 
off  to  the  ligamentum  teres  in  the  region  of  the  notch  in  the 
acetabulum  ;  while,  in  the  case  of  the  knee  joint,  the  obturator 
nerve  sends  filaments  which  enter  that  articulation  at  its  pos- 
terior part,  and  which  are  probably  intimately  associated 
with  its  internal  structures.  The  close  relation  which  this 
nerve  bears  to  the  sacro-iliac  articulation  renders  it  probable 

'  See  page  724  of  this  volume. 


THE  OBTURATOR  NERVE. 


739 


that  some  small  filaments  from  the  obturator  nerve  could  be 
traced  to  this  joint,  although  anatomical  authors  do  not  men- 
tion this  fact  as  proven.    In  relation  to  this  point,  I  quote  from 


Fig.  227. —  The  mitscular  brandies  of  the  anterior  and  internal  portions  of  the  thigh. 

(Sappey.) 

1,  anterior  crural  nerve  ;  2,  branch  which  it  furnishes  to  the  iliacus  muscle  ;  3,  twig  which 
it  sends  to  the  internal  portion  of  the  psoas  muscle  :  4,  middle  cutaneous  branch  of 
the  anterior  crural,  whose  three  branches  have  been  divided  close  to  their  origin  in 
order  to  show  the  branches  to  the  quadriceps  extenso^  and  the  internal  saphenous 
nerve,  which  are  more  deeply  placed  ;  5  and  6,  muscular  filaments  of  the  internal 
cutaneous  nerve ;  7,  origin  of  the  cutaneous  branches  which  pierce  the  fascia  lata  at 
the  level  of  the  saphenous  opening ;  8,  deep  or  anastomotic  filament  of  the  internal 
cutaneous  branch  of  the  anterior  crural ;  9,  branches  to  the  rectus  muscle ;  10, 
branches  to  the  vastus  externus  ;  11,  branches  to  the  vastus  internus;  12,  12,  inter- 
nal saphenous  nerve;  13,  patellar  branch  of  this  nerve;  14,  its  vertical  or  tibial 
branch ;  15,  obturator  nerve  ;  16,  branch  which  it  furnishes  to  the  adductor  longus ; 
17,  branch  to  the  adductor  brevis;  18,  branch  to  the  gracilis  ;  19,  branch  to  the  ad- 
ductor magnus ;  20,  lumbo-sacral  trunk  ;  21,  junction  of  this  nerve  with  the  first 
sacral  nerve ;  22,  22,  lumbar  and  sacral  portions  of  the  sympathetic ;  23,  external 
cutaneous  nerve. 


740  THE  SPINAl  NERVES. 

the  most  excellent  monograph  of  Hilton'  as  follows :  "lam 
disposed  to  think  it  sends  some  filaments  to  that  articulation, 
or,  at  any  rate,  it  lies  close  to  it  and  would  be  likely  to  suffer 
from  its  proximity  to  it  when  diseased."  Now,  this  distribu- 
tion to  the  internal  portions  of  two  joints,  and  possibly  to  a 
third,  is  the  best  possible  explanation  of  the  fact  that  the  ob- 
turator nerve  is  the  most  frequent  source  of  transmission  of 
sympathetic  pains,  in  case  the  hip  joint  be  the  seat  of  the 
disease,  since  the  situation  of  its  filaments  causes  it  to  per- 
ceive the  first  inflammatory  changes  within  the  hip  ;  and  the 
effects  of  this  irritation  are  naturally  manifested  in  its  termi- 
nal filaments — in  the  knee  joint  and  the  skin  upon  the  inner 
side  of  that  articulation. 

When  we  consider  the  course  of  the  obturator  nerve  more 
in  detail,  we  will  perceive  thsit  pain  in  the  region  of  the  Tcnee 
may  be  due  to .  other  causes  than  morbus  coxarius.  It  may 
be  the  external  evidence  of  disease  of  the  third  or  fourth  lum- 
bar vertebrae,  of  disease  of  the  sacro-iliac  articulation,  of  a 
psoas  abscess  pressing  upon  it,  and,  if  the  pain  be  confined  to 
the  left  side,  a  distention  of  the  sigmoid  flexure  of  the  colon 
by  faeces,  or  a  malignant  tumor  of  that  portion  of  the  colon 
or  of  the  rectum  might  create  pain  in  this  region.  It  is  well, 
therefore,  when  a  patient  suffering  from  a  pain  localized  upon 
the  inner  aspect  of  the  knee  joint  is  brought  to  you,  to  care- 
fully examine  all  the  different  portions  of  the  course  of  the 
obturator,  anterior  crural,  and  sciatic  nerves  before  you  de- 
cide as  to  the  exciting  cause  of  the  pain,  remembering  always 
that  pain  can  be  perceived  through  no  other  structures  than 
the  nerves  which  are  distributed  to  the  region  where  the  pain 
is  felt,  and  that,  by  following  the  course  of  the  nerve  suffer- 
ing from  irritation,  the  seat  of  the  disease  to  which  the  pain 
is  due  may  be  confidently  sought  for. 

The  distribution  of  the  obturator  nerve  affords  us  some 
lessons  as  to  the  physiological  groupings  of  the  muscles  which 
act  upon  the  thigh  and  leg.  It  first  supplies  the  obturator 
extemus,  and  then  the  adductor  brevis,  the  adductor  longus, 

'  Op.  cit. 


DISTRIBUTION   OF  TEE   OBTURATOR  NERVE.  741 

the  adductor  magnus,  and  tlie  gracilis.  In  some  cases  the 
pectineus  is  supplied  by  this  nerve  or  the  accessory  obturator 
nerve,  but  its  chief  source  of  supply  is  undoubtedly  from  the 
anterior  crural.  This  fact  would  seem  to  indicate  that  the 
gracilis  muscle,  whose  supply  from  the  obturator  nerve  is 
very  constant,  should  be  classed  as  an  adductor  muscle,  rather 
than  as  a  flexor,  and  that  this  is  its  true  action  seems  well 
proven  on  mechanical  principles.  Its  point  of  insertion  is 
just  below  the  central  point  of  the  limb  which  it  moves,  hence, 
it  seizes  the  limb  just  beyond  the  central  point,  between  the 
fulcrum  (the  hip  joint)  and  the  resistance,  and  is  thus  able  to 
greatly  assist  the  adductor  muscles.  The  obturator  nerve  is 
thus,  physiologically  considered,  the  adductor  nerve  of  the 
lower  extremity,  while  the  muscles  which  it  supplies  also  act 
as  external  rotators  of  the  thigh,  on  account  of  the  obliquity 
of  their  fibers.  That  the  pectineus  muscle  acts  as  a  flexor  as 
well  as  an  adductor  is  proven  by  its  nerve  supply,  as  well  as 
by  the  direction  of  its  fibers  and  its  points  of  origin  and  in- 
sertion, since  it  receives  filaments  both  from  the  anterior  cru- 
ral and  obturator. 

CLINICAL   POINTS   PERTAINING  TO  THE   OBTURATOR   NERVE. 

The  diagnostic  value  of  pain  in  the  region  of  the  knee 
joint  as  an  evidence  of  disease  in  other  localities,  to  which 
the  obturator  nerve  is  either  distributed  or  with  which  it 
bears  some  intimate  relations,  has  been  discussed  already  at 
some  length. '  Such  a  pain  iriay  be  dependent,  however,  also 
upon  lesions  interfering  with  the  free  action  of  the  anterior 
crural  and  sciatic  nerves,  and,  for  that  reason,  the  course  of 
these  three  nerves  should  always  be  carefully  examined  be- 
fore a  positive  diagnosis  can  be  made  as  to  the  exciting  cause 
of  pain  in  the  region  of  the  knee. 

The  obturator  nerve  is  even  less  frequently  affected  with 
isolated  paralysis  than  the  anterior  crural,  but,  if  so,  it  may 
be  referable  to  the  same  list  of  causes.  In  addition  to  the 
causes  mentioned,  may  be  added,  however,  compression  of  the 

*  See  page  734  of  this  volume. 


742  TEE  SPINAL  NERVES. 

obturator  nerve  from  a  strangulated  hernia  through  the  obtu- 
rator foramen,  the  pressure  exerted  by  the  head  of  a  foetus 
during  its  passage  through  the  pelvis,  and  the  use  of  forceps 
during  difficult  labors. 

From  what  has  been  said  as  to  the  supply  of  muscles  by 
this  nerve,  it  is  apparent  that  a  patient  afflicted  with  obtu- 
rator paralysis  can  not  adduct  the  thigh,  or  perform  the  acts 
of  pressing  the  knees  tightly  together  or  of  crossing  the 
affected  leg  over  the  other.  Since  the  adductor  muscles  assist 
in  the  external  rotation  of  the  thigh,  this  movement  is  im- 
paired, especially  in  the  sitting  posture,  when  the  external 
rotators  attached  to  the  great  trochanter  are  rendered  inert. 
The  affected  leg  soon  becomes  fatigued  in  walking,  and  riding 
upon  horseback  is  difficult,  since  the  knees  can  not  grasp  the 
saddle.  Some  disturbances  of  sensibility  may  be  detected  in 
the  regions  of  the  skin  supplied  by  this  nerve  ;  these  will  be 
the  same  in  character  as  those  mentioned  as  existing  in  crural 
paralysis. ' 

THE  ACCESSORY   OBTURATOR   NERVE. 

This  nerve  is  sometimes  wanting.  When  it  is  present,  its 
origin  is  extremely  variable.  It  may  arise  from  the  third  and 
fourth  lumbar  nerves  ;  from  the  fourth  lumbar  and  obturator 
nerves  ;  or  by  separate  filaments  derived  from  the  second, 
third,  and  fourth  lumbar  nerves.  It  descends  along  the  inner 
side  of  the  psoas  muscle,  crosses  in  front  of  the  pubes,  passes 
behind  the  pectineus  muscle,  and  there  divides  into  branches 
to  the  pectineus  and  the  hip  joint.  It  usually  gives  off  a  large 
branch  of  communication  to  the  obturator  nerve  (which  is 
often  larger  than  the  continuation  of  the  accessory  nerve  it- 
self), and  terminates  as  a  cutaneous  nerve  to  the  thigh  and 
leg. 

The  frequent  absence  of  this  nerve  deprives  it  of  any  clin- 
ical importance,  as  it  is  impossible  in  any  one  case  to  decide 
if  pain  in  the  regions  supplied  by  the  obturator  nerve  is  partly 
due  to  the  accessory  obturator  or  not,  while  the  variations  in 

'  See  page  736  of  this  volume. 


THE  SACRAL  NERVES.     '  743 

the  method  of  origin  of  the  nerve  renders  it  impossible  to 
definitely  decide  as  to  the  seat  of  irritation,  provided  the 
pain  could  be  traced  to  the  accessory  nerve  and  localized 
above  the  pelvis. 

THE  SACRAL  NERVES. 

We  now  have  reached,  in  the  natural  progress  of  this 
course  of  lectures,  the  terminal  nerves  of  the  spinal  cord. 
As  was  the  case  with  those  of  the  lumbar  region,  the  sacral 
nerves  divide  into  anterior  and  posterior  divisions,  but  they 
differ  from  the  lumbar  nerves  in  the  fact  that  these  ante- 
rior and  posterior  divisions  escape  from  separate  foramina 
in  the  sacrum,  while,  in  the  portions  of  the  cord  above  the 
sacral  region,  the  spinal  nerves  divide  after  their  escape 
from  the  inter-vertebral  foramina.  These  nerves  form,  by 
their  anterior  divisions  and  the  addition  of  the  lumbo-sacral 
cord,  the  sacral  plexus  ;  while  their  posterior  divisions  are 
distributed  to  the  muscles  of  the  lower  lumbar  region  and 
to  the  integument  of  the  gluteal,  sacral,  and  coccygeal  re- 
gions. 

The  sacral  pleccus  is  triangular  in  shape,  and  is  formed 
by  the  lumbo-sacral  cord,  the  three  upper  sacral  nerves 
(their  anterior  divisions),  and  a  portion  of  the  fourth  sa- 
cral nerve.  Its  constituent  fibers  converge  to  form  one  flat- 
tened cord,  which  leaves  the  pelvis  through  the  lower  part 
of  the  great  sacro-sciatic  foramen,  below  the  pyriformis 
muscle,  while,  within  the  pelvis,  the  plexus  lies  upon  the 
pyriformis  muscle,  and  is  covered  by  the  pelvic  fascia  and 
the  two  terminal  branches  of  the  anterior  division  of  the 
internal  iliac  artery  (the  sciatic  and  pudic).  The  branches 
which  are  given  off  by  this  plexus  are  arranged,  in  the 
table  which  I  now  show  you,  in  such  a  way  as  to  make 
them  apparent  to  the  eye,  while  the  distribution  of  each 
is  shown  in  the  next  table  in  detail.  The  first  table  is 
not  intended  to  exhibit  alone  the  branches  of  the  sacral 
plexus,  but  rather  to  give  the  general  arrangement  of  the 


744 


THE  SPINAL  NERVES. 


sacral  nerves  in  their  entirety.  You  will  perceive  that 
the  arrangement  of  both  the  anterior  and  posterior  divis- 
ions is  considered,  and  that  the  component  parts  of  the 
sacral  plexus,  as  well  as  its  main  subdivisions,  are  clearly  set 
forth. 

KERVES   OF   THE   SACRAL   REGION.^ 


SACRAL 
NERVES. 


Posterior 
divisions.  ") 


I  External 

I  branches. 

{ 


Anterior 
divisions.  ^ 


Internal 

branches. 


f  LUMBO-SACRAL 

CORD. 

1st  sacral 

nerve. 

2d  sacral 


3d  sacral 


Part  of  4th  sa- 
cral nerve. 


Form  anastomotic  loops  on  the  back  part 
of  the  sacrum  and  on  the  posterior  aspect 
of  the  great  sacro-sciatic  ligament, 

Terminate  in  cu(a?icous  hrcmches  in  the 
gluteal  region. 

Are  distributed  to  the  multifidus  spinae 
muscle, 

The  back  part  of  the  coccyx  is  supplied  by 
the  two  lower  nerves. 


(1)  Superior  gluteal  nerve, 

(2)  Muscular  branches, 

(3)  Small  sciatic  nerve, 

(4)  Great  sciatic  nerve, 

(5)  PUDIC   NERVE, 


.  SACRAL 
r  PLEXUS. 


^  (6)  Articular. 


Each  of  the  five  branches  of  the  sacral  plexus,  as  well  as 
those  included  in  the  muscular  group,  to  which  no  special 
names  are  given,  will  now  be  separately  described.  I  have 
endeavored  to  embrace  in  this  second  table  all  the  points 
pertaining  to  the  purely  anatomical  distribution  of  each 
of  these  nerves,  but  much  of  interest,  from  a  clinical  as- 
pect, still  remains  in  relation  to  some  of  them,  which  can 
not  be  shown  in  a  tabular  form.  This  table  will,  however, 
prove  of  assistance  to  you  in  reviewing  the  distribution  of 
the  nerve  which  is,  at  any  time,  under  discussion,  and,  fur- 
thermore, avoid  lengthy  descriptions  of  a  purely  anatomical 
character. 


'  Taken  from  the  "Essentials  of  Anatomy  "  (Darling  and  Ranney).     G.  P.  Putnam's 
Sons,  New  York,  1880. 


THE  SUPERIOR   GLUTEAL  NERVE. 


745 


DISTRIBUTION   OF  THE   BRAN^CHES   OF   THE   SACRAL   PLEXUS. 


SACRAL   , 
PLEXUS  ^ 


Superior 

GLUTEAL. 


Muscular 
branches. 


Articular  ; 
branches, 


Small 

SCIATIC 
NERVE. 


cr        .     u        ^     \  Gluteus  medius  muscle, 
^t^^mor  branch.  |  Gluteus  minimus  muscle. 

{Gluteus  medius  muscle, 
Gluteus  minimus  muscle, 
Tensor  vaginae  femoris. 
Pyriformis, 
Obturator  internus, 
Gemellus  superior, 
Gemellus  inferior, 
Quadratus  femoris. 

-  To  hip  joint. 

'  Lifcvior   gluteal  k  Gluteus  maximus  muscle, 
branch. 


Inferior   puden- 
dal branch. 


Cutaneous 

branch. 


\  Integument  of  the  side  of  the  penis  or  vulva. 
f  Integument  of  perinaeum, 

Integument  of  upper  and  inner  part  of  the 
thigh, 

Integument  of  scrotum  or  labium. 


Ascending. 
Descending. 


Great 

SCIATIC  A  Muscular 


Terminal 


Articular  (to  the  hip  joint). 


Integument  over  the  gluteus 
maximus  muscle, 

{Integument  of  the  inner  and 
outer  sides  of  posterior 
aspect  of  the  thigh. 


PUDIC 

NERVE. 


Adductor  magnus, 
Semi-membranosus, 
Semi-tendinosus, 
Biceps  flexor  cruris. 
External  popliteal  nerve, 
Internal  popliteal  nerve. 
Cutaneous    or  i  Integument  of  anal  region, 
superficial   <      scrotum,  penis,  and  labia, 
perineal.      {  Sphincter  ani  muscle. 
y  Muscular  .     .  -{  Muscles  of  the  perinaBum. 
Inferior  hemorrhoidal. 

Dorsal  nerve  of  j   Integument  of  the  dorsum  of  the  penis, 
penis.  \  Branch  to  corpora  cavernosa  of  the  penis. 


Perineal 


THE   SUPERIOR   GLUTEAL   NERVE. 

This  nerve  arises  from  the  back  part  of  the  lumbo-sacral 
cord,  and,  while  generally  included  as  a  branch  of  the  sacral 
plexus,  can  not  be,  therefore,  properly  regarded  as  a  nerve  of 
sacral  origin.  It  escapes  from  the  pelvis  through  the  upper 
part  of  the  great  sacro-sciatic  foramen,  in  company  with  the 
gluteal  vessels,  lying  above  the  pyriformis  muscle.  It  divides 
into  a  superior  and  an  inferior  branch,  as  is  shown  in  the 
table '  to  which  I  have  called  your  special  attention,  the  for- 
mer of  which  accompanies  the  superior  gluteal  artery  between 

'  Modified  from  a  table  taken  from  "  The  Essentials  of  Anatomy  "  (Darling  and  Ran- 
ney).       G.  P.  Putnam's  Sons,  New  York,  1881. 
^  See  the  foregoing  table. 


746  TEE  SPIRAL  NERVES. 

the  gluteus  medius  and  minimus  muscles,  while  the  latter 
passes  between  the  same  muscles,  but  lower  than  its  fellow. 

The  distribution  of  this  nerve  to  the  gluteus  medius, 
gluteus  minimus,  and  tensor  vaginae  femoris  muscles,  stamps 
it  as  the  one  which  presides  chiefly  over  the  act  of  internal 
rotation  of  the  thighs  since  these  three  muscles  are  the  only 
ones  which  can  perform  this  limited  movement  of  the  femur. 
Its  cutaneous  distribution  again  confirms  the  axioms  of  Hil- 
ton ;  *  since  the  skin  over  these  muscles  is  thus  supplied,  while 
some  filaments  running  over  the  fascia  lata,  to  which  the 
tensor  vaginae  femoris  is  attached,  can  be  demonstrated. 

CLINICAL  POINTS   PERTAINING  TO  THE   SUPERIOR   GLUTEAL  NERVE. 

The  cutaneous  covering  of  the  gluteus  medius  and  mini- 
mus muscles  is  not  alone  supplied  by  the  gluteal  nerve,  as 
the  lumbar  nerves  may  be  seen  coursing  along  over  the  lower 
part  of  the  abdomen,  then  passing  over  the  crest  of  the  ilium, 
and  finally  reaching  this  part  of  the  thigh.  While  this  might 
seem,  at  a  first  glance,  to  be  a  peculiar  admixture  of  lumbar 
and  sacral  nerves,  yet,  on  returning  to  a  point  just  made,  we 
discover  that  the  superior  gluteal  nerve  is  of  lumbar  origin, 
although  apparently  a  branch  of  the  sacral  plexus;  hence, 
the  skin,  supplied  by  branches  of  lumbar  origin,  protects  all 
those  regions  to  which  muscular  branches  derived  from  the 
same  sources  can  be  traced.  We  see  the  region  of  the  gluteus 
maximus  muscle  apparently  avoided'  by  the  nerves  which 
descend  from  the  abdomen  to  supply  the  skin  of  the  adjoin- 
ing region,  and,  when  we  seek  for  an  explanation  of  the  fact, 
we  find  that  this  muscle  is  supplied  by  the  small  sciatic  nerve 
(derived  from  the  sacral  plexus,  and  having  no  connection 
with  the  lumbar  nerves) ;  hence,  the  integument  covering 
that  muscle  could  not  be  supplied  by  nerves  whose  source  of 
origin  woi^ld  prevent  a  perfect  sympathy  between  the  skin 
and  the  muscular  structures  which  it  covers. 

The  relation  of  this  nerve  to  the  gluteal  artery,  as  it  es- 
capes from  the  great  sacro-sciatic  foramen,  gives  it  a  surgical 

'  See  page  646  of  this  volume.  ^  Hilton,  op  cit. 


DISTRIBUTION   OF  SUPERIOR   GLUTEAL  NERVE.       747 

importance,  as  that  vessel  is  sometimes  ligated  for  haemor- 
rhage from  some  of  its  branches. 

The  three  muscles  supplied  by  the  superior  gluteal  nerve, 
if  acting  in  connection  with  the  gluteus  maximus  muscle,  be- 
come the  abductors  of  the  hip  joint,  while  the  posterior 
half  of  the  gluteus  medius  and  the  posterior  fifth  of  the 
gluteus  minimus  assist  in  extension  of  the  thigh  upon  the 
trunk,  since  their  origin  lies  on  a  plane  posterior  to  their 
insertion  into  the  trochanter.  Thus  we  are  enabled  to  class 
the  superior  gluteal  nerve  as  a  factor  in  three  of  the  move- 
ments of  the  hip  joint,  viz.,  internal  rotation,  abduction,  and 
extension. 

When  the  superior  gluteal  nerve  is  subjected  to  irritation, 
a  spasmodic  condition  of  the  gluteal  muscles  may  be  pro- 
duced. It  is  extremely  rare  to  have  such  a  condition  devel- 
oped in  the  glutei  muscles  alone,  but  one  such  case  is  reported 
by  Kemak.  In  this  case  the  spasms  of  the  legs  consisted  of  a 
series  of  gluteal  contractions  which,  when  the  patient  would 
attempt  to  walk,  would  draw  the  leg  backward  and  render  it 
fixed  in  that  position.  We  see,  however,  the  glutei  muscles 
frequently  affected  with  spasm  (in  connection  with  muscles  of 
the  lower  extremity  supplied  by  other  nerves)  in  tetanus, 
rheumatic  inflammation  of  the  hip  joint,  arthralgia,  neural- 
gia, and  lesions  within  the  pelvis  which  affect  the  sacral 
plexus. 

The  gluteal  muscles  may  be  affected  with  paralysis^  but 
it  is  rare  that  the  paralysis  is  confined  exclusively  to  that 
region.  As  a  rule,  these  muscles  become  affected  as  the  result 
of  lesions  which  involve  the  sacral  plexus  to  a  greater  or  less 
extent,  such  as  spinal  diseases,  tumors  in  the  spinal  canal  or 
pelvis,  lesions  of  the  cauda  equina,  fractures  of  the  sacrum, 
fractures  of  the  pelvis,  etc.,  so  that  the  paralysis  of  the  glutei 
muscles  is  masked  by  a  similar  condition  of  muscles  supplied 
by  other  nerves.  When  the  glutei  muscles  are  paralyzed,  in 
connection  with  the  tensor  vaginae  femoris,  the  pyriformis, 
and  the  obturator  internus,  as  is  more  frequently  observed, 
fche  rotation  of  the  thigh  inward  becomes  impossible,  and  out- 


Y48  THE  SPINAL  NERVES. 

ward  rotation  also  becomes  somewhat  impaired,  as  the  adduc- 
tor group  and  the  psoas  and  iliacus  have  chiefly  to  perform  it. 
Abduction  of  the  thigh  is  rendered  extremely  difiicult,  and, 
if  the  paralysis  be  complete,  absolutely  impossible,  while  flex- 
ion of  the  thigh  is  impaired  and  limited  in  its  extent.  When 
such  patients  attempt  to  walk,  the  glutei  muscles  no  longer 
preserve  the  relations  of  the  trunk  to  the  thighs,  and  a  diffi- 
culty in  preserving  the  balance  is  therefore  present.  This  is 
especially  noticeable  when  an  attempt  to  ascend  a  flight  of 
steps  is  made,  as  the  trunk  has  then  to  be  inclined'  forward. 
The  affected  muscles  usually  undergo  atrophy  when  thus  de- 
prived of  their  normal  power,  and  the  gluteal  region  loses  its 
natural  roundness  and  flrmness. 

The  disturbances  of  sensibility  which  may  coexist  with 
this  type  of  paralysis  will  depend  somewhat  upon  the  seat  of 
the  exciting  cause,  as  well  as  upon  its  character.  Pain  may 
be  a  means  of  making  a  diagnosis  of  the  development  of  the  ex- 
citing lesion  before  the  paralysis  is  developed,  if  the  precepts 
given  you  in  the  earlier  lectures  of  this  course  be  applied, ' 
remembering  always  that  the  cause  of  the  pain  must  be  sought 
for  along  the  course  of  the  cutaneous  nerves  which  supply 
the  region  where  pain  is  felt,  and  that  the  omission  on  your 
part  of  one  of  the  nerves  whose  filaments  are  present  in  the 
region  of  pain  may  entail  a  complete  failure  in  discovering 
the  cause. 

THE   MUSCULAR   BRANCHES   OF  THE   SACRAL   PLEXUS. 

By  reference  to  the  table  of  the  distribution  of  the  vari- 
ous branches  of  the  sacral  plexus,"  you  will  perceive  that  ^yq 
muscles  receive  a  direct  supply  from  it  through  branches  which 
are  not  specially  named,  being  included  in  the  muscular  set — 
these  five  muscles  being  the  pyriformis,  obturator  internus, 
gemellus  superior,  gemellus  inferior,  and  quadratus  femoris. 
If  we  consider  the  function  of  these  five  muscles,  it  will  be 
evident  that  they  should  receive  their  nerve  supply  from  the 
same  source,  provided  the  axiom  of  Hilton — that  the  nerve 

'  See  page  646  of. this  volume.  '  See  page  745  of  this  volume. 


MUSCULAR  BRANCHES  OF  THE  SACRAL  PLEXUS.      749 

distribution  of  muscles '  is  a  guide  to  their  function — be  true, 
as  they  all  assist  in  the  external  rotation  of  the  tJiigJi  by 
their  action  upon  the  great  trochanter  of  the  femur.  The 
situation  of  these  five  muscles  is  such  that  a  direct  supply 
from  the  sacral  plexus  might  almost  be  inferred.  The  pyri- 
formis  and  obturator  internus  muscles  arise  from  within  the 
pelvis  and  escape  from  its  cavity  by  means  of  the  greater 
and  lesser  sacro-scintic  foramina,  while  the  two  gemelli 
muscles  and  the  quadratus  femoris  are  attached  to  the 
OS  innominatum  in  the  immediate  vicinity  of  these  two 
foramina.  Now,  the  sacral  plexus  lies  upon  the  pyriformis 
muscle,  and  would  naturally  supply  it,  while  the  other  four 
muscles  bear  such  an  intimate  relation  with  the  pyriformis, 
as  it  escapes  from  the  pelvis,  as  to  render  a  supply  from  the 
sacral  plexus  easy,  while  the  similarity  of  function  between 
the  five  muscles  would  presuppose  a  nerve  supply  from  the 
same  source. 

In  the  lectures  upon  the  obturator  and  anterior  crural 
nerves,  the  action  of  the  adductor  and  flexor  groups  of  mus- 
cles, in  assisting  the  external  rotation  of  the  thigh,  was  dis- 
cussed, and  we  here  come  upon  another  group  of  muscles 
which  also  tend  to  perform  the  same  movement  of  the  lower 
limb.  The  questions  may  arise  to  your  minds — how  are  we 
able  to  explain  a  dissimilarity  in  the  sources  of  motor  power 
in  groups  of  muscles  which  have  a  common  function  to  per- 
form? How  are  we  able  to  reconcile  the  axioms  of  nerve 
supply,  so  often  quoted,  with  this  apparent  contradiction  ? 
The  answer  to  both  of  these  questions  is  settled  by  a  careful 
scrutiny  of  the  combined  actions  of  each  of  these  separate 
groups  of  muscles.  In  the  first  place,  the  five  muscles  of  the 
thigh,  supplied  by  the  sacral  plexus  of  nerves  through  its 
muscular  branches,  can  not  perform  the  movement  of  exter- 
nal rotation  of  the  thigh  when  the  subject  is  in  the  sitting 
posture.  It  is  in  this  relative  position  of  the  thigh  and  trunk 
that  the  adductor  group  of  muscles,  aided  by  the  psoas  and 
iliacus,  become  important  factors  in  the  movement  of  external 

5Q  1  Op.  cit. 


750  THE  SPINAL  NERVES. 

rotation ;  and  it  is  to  be  remembered  that  this  movement  is 
but  a  secondary  function  with  these  latter  muscles,  since  they 
are  designed  chiefly  to  insure  adduction  and  flexion  of  the 
thigh.  Each  muscle  of  a  group  is  usually  supplied  by  that 
nerve  whose  branches  are  also  distributed  to  others  of  that 
group  which  aid  in  its  primary  action,  rather  than  in  any 
secondary  movement  in  which  it  may  chance  to  participate  ; 
hence  the  psoas  and  iliacus  derive  their  power  from  the  ante- 
rior crural,  the  adductor  muscles  from  the  obturator,  and  the 
five  muscles  posterior  to  the  hip  joint  from  the  sacral  plexus, 
and  thus  the  primary  action  of  each  group  is  indicated  by  the 
nervous  supply,  as  well  as  by  the  points  of  origin  and  inser- 
tion of  each  muscle. 

THE   SMALL  SCIATIC   NERVE. 

This  branch  of  the  sacral  plexus  is  given  off  from  its  lower 
and  posterior  part,  and  escapes  from  the  pelvis  through  the 
sacro-sciatic  foramen,  below  the  pyriformis  muscle,  in  com- 
pany with  the  sciatic  vessels.  It  descends  beneath  the  gluteus 
maximus  muscle,  in  which  region  it  lies  to  the  inner  side  of 
the  great  sciatic  nerve,  and  continues  beneath  the  fascia  lata 
as  low  down  as  the  popliteal  space,  where  it  perforates  this 
fascia  and  joins  with  the  external  saphenous  nerve,  giving  off 
also  cutaneous  branches  of  its  own  to  the  popliteal  space  and 
the  back  of  the  calf. 

The  branches  of  this  nerve,  which  are  enumerated  in  the 
table,'  comprise  the  inferior  gluteal,  the  inferior  pudendal, 
and  the  cutaneous  filaments  distributed  over  the  gluteus  max- 
imus muscle,  and  the  regions  previously  mentioned.  The  fact 
that  this  nerve  sujyplies  the  gluteus  maximus  muscle  with 
motor  power  gives  it  an  importance  to  the  anatomist,  since 
this  muscle  is  one  of  the  most  important  factors  in  regulating 
the  position  of  the  trunk  and  the  lower  extremity  during  all 
the  various  attitudes  assumed  by  the  living  subject ;  but 
there  are  also  some  suggestions  of  value  which  have  been 
thrown  out  by  previous  authors  upon  anatomy  which  will 

^  Sec  page  745  of  this  volume. 


THE  SMALL  SCIATIC  NERVE, 


751 


merit  your  closest  attention,   especially  as  they  are  omitted 
in  some  of  the  descriptive  text-books. 


Fig.  228. — The  small  sciatic  nerve,  with  its  branches  of  distribution  and  termination. 

(Sappey.) 
1,  superior  gluteal  nerve ;  2,  small  sciatic  nerve ;  3,  3,  3,  branches  to  the  gluteus 
maximus ;  4,  branch  to  the  pyramidalis ;  5,  internal  pudendal  branch  of  the  small 
sciatic ;  6,  fcmoro-popliteal  branch  of  the  same  nerve ;  7,  7,  trunk  of  the  great  sci- 
atic ;  8,  branch  which  it  gives  to  the  long  head  of  the  biceps ;  9,  branch  to  the  short 
head  of  the  same  muscle;  10,  10,  branch  to  the  senii-{cndinosus  (the  latter  muscle 
has  been  divided  and  turned  back,  to  show  the  semi-membranosus) ;  11,  11,  branch 
to  the  semi-membranosus;  12,  12,  another  branch,  rising  from  the  common  trunk 
with  the  preceding  nerve,  and  passing  under  the  semi-membranosus  to  be  distributed 
to  the  adductor  raagnus ;  13,  external  popliteal  nerve;  14,  internal  popliteal  nerve  ; 
15,  filament  to  the  plantaris  ;  16,  16,  nerves  to  the  gastrocnemius;  17,  origin  of  the 
external  saphenous  nerve. 

In  the  first  place,  this  nerve  sends  filaments  to  the  peri- 
nseum  and  genitals '  of  the  male  and  female,  after  supplying 

'  In  the  female,  the  filaments  probably  go  to  the  vnlva  and  vagiiia  ;  but,  in  the  male, 
the  side  of  the  penis  is  thus  supplied. 


752  THE  SPINAL  NERVES. 

the  gluteus  maximus  muscle  ;  and  the  suggestion  is  made  by 
Hilton,  in  reference  to  this  point,  that  the  action  of  this 
muscle  in  its  relation  to  coitus  may  tend  to  explain  the  neces- 
sity for  a  sympathy  between  these  two  parts  by  means  of  a 
common  nerve  supply. 

Again,  the  recognition  of  the  perineal  branch  of  the  small 
sciatic  nerve  is  sometimes  important  in  practice.  If  you  care 
to  trace  this  nerve  upon  the  dead  subject,  you  will  find  that 
it  escapes  from  beneath  the  perineal  border  of  the  gluteus 
maximus  muscle,  runs  along  the  outer  portion  of  the  peri- 
nseum,  and,  finally,  sends  cutaneous  filaments  to  the  sides  of 
the  penis.  The  perineal  region  is  also  supplied  by  the  peri- 
neal branches  of  the  pudic  nerve,  which  escape,  posteriorly 
to  those  of  the  sciatic,  from  beneath  the  same  muscle.  Now, 
either  of  these  two  nerves  may  be  the  cause  of  a  pain  referred 
to  the  perinseum  and  the  penis,  and  their  points  of  escape 
from  beneath  the  gluteus  maximus  muscle  are  so  placed  as  to 
render  them  frequently  subjected  to  pressure  from  sitting 
upon  hard  or  uneven  seats.  It  is  thus  possible  for  pains, 
referred  to  the  penis,  to  be  wrongly  attributed  to  diseases  of 
the  bladder,  calculus  in  the  bladder,  urethral  troubles,  and 
all  other  types  of  disease  which  are  commonly  indicated  by 
more  or  less  pain  in  that  locality,  when  the  cause  may  be 
found  and  correctly  diagnosed  by  following  up  the  course  of 
the  perineal  branch  of  the  small  sciatic.  Such  a  case  is 
reported  by  Hilton,  where  prominent  surgeons  of  Europe, 
among  them  Mr.  Key,  had  diligently  and  unsuccessfully 
searched  for  the  cause  of  a  pain,  referred  to  the  penis,  along 
the  course  of  the  pudic  nerve,  and  where  the  patient  had 
been  treated  for  disease  of  the  bladder,  a  careful  examination 
subsequently  revealing  the  true  cause  to  be  a  spot  of  hardened 
tissue  pressing  upon  the  perineal  branch  of  the  small  sciatic 
nerve,  which  was  cured  (as  well  as  the  pain  which  it  created) 
by  the  application  of  nitric  acid  over  the  seat  of  thickening. 
It  is,  therefore,  well  to  remember  the  course  of  this  branch, 
as  well  as  those  of  the  pudic  nerve,  when  investigating  for  the 
cause  of  pain  in  the  penis  or  perineum. 


THE  PUDIC  NERVE.  753 


THE   PUDIC   KERVE. 


This  branch  of  the  sacral  plexus  arises  from  its  lower  part, 
and  immediately  escapes  from  the  pelvis  by  means  of  the 
great  sacro-sciatic  foramen  in  company  with  the  pudic  artery, 
the  sciatic  vessels  and  nerves,  and  the  gluteal  vessels  and 
nerves.  The  situation  of  the  nerve  in  this  foramen  is  on  the 
inner  side  of  the  great  sciatic  nerve,  both  of  which  escape 
through  the  lower  part  of  the  foramen,  beneath  the  pyri- 
formis  muscle.  The  pudic  nerve  then  reenters  the  pelvis 
through  the  lesser  sacro-sciatic  foramen,  in  company  with  its 
artery,  and  immediately  gives  oif  its  inferior  hemorrhoidal 
branch.  From  this  point  the  nerve  passes  along  the  outer 
wall  of  the  ischio-rectal  fossa,  lying  above  the  pudic  artery 
(both  artery  and  nerve  being  covered  by  the  obturator  fas- 
cia), and  divides  into  the  perineal  branch  and  the  dorsal  nerve 
of  the  penis. 

Of  these  three  branches  of  the  pudic  nerve,  the  distribu- 
tion has  been  given  in  a  previous  table,  but  with  less  detail 
than  the  subject,  perhaps,  demands. 

The  inferior  liemorrlioidal  nerve  occasionally  arises  di- 
rectly from  the  sacral  plexus  rather  than  as  a  branch  of  the 
pudic ;  its  course  runs  along  the  ischio-rectal  fossa,  and  it  is 
distributed  to  the  sphincter  muscles  of  the  rectum  and  the 
skin  around  the  region  of  the  anus.  It  communicates  freely 
in  this  region  with  the  superficial  perineal  and  inferior  pu- 
dendal nerves. 

The  'perineal  nerve  is  the  largest  branch  of  the  pudic,  and 
accompanies  the  superficial  perineal  artery.  It  divides  into 
two  sets  of  terminal  filaments — the  cutaneous  or  superficial 
perineal  nerves  and  muscular  branches.  The  former  of  these 
give  a  few  twigs  to  the  sphincter  ani  and  levator  ani  muscles, 
but  are  chiefly  distributed  to  the  integument  of  the  perinseum, 
scrotum,  labium,  and  the  penis,  communicating  freely,  in  the 
region  of  the  anus,  with  the  inferior  hemorrhoidal  nerve. 
The  muscular  branches  usually  arise  from  the  pudic  nerve 
by  a  common  trunk,  which  passes  forward  and  inward  un- 


754  THE  SPINAL  NERVES. 

derneath  the  transverse  perinei  muscle ;  its  terminal  fila- 
ments are  given  off  to  the  transverse  perinei,  erector  penis, 
accelerator  urinse,  and  compressor  urethrse  muscles,  and  a 
twig  is  often  sent  to  the  bulb  of  the  urethra. 

The  dorsal  nerve  of  the  penis  is  the  smaller  terminal  fila- 
ment of  the  pudic  nerve,  which  accompanies  the  pudic  artery 
along  the  rami  of  the  pubes  and  ischium,  between  the  layers 
of  the  deep  perineal  fascia ;  it  then  pierces  the  suspensory  lig- 
ament of  the  penis  and  continues  its  way  along  the  dorsum  of 
that  organ  as  far  as  the  glans  penis.  It  gives  a  branch  to  the 
corpus  cavernosum,  and  supplies  the  integument  of  the  dor- 
sum '  of  the  penis ;  in  the  female  the  course  of  the  nerve  is 
about  the  same,  although  the  size  of  the  nerve  is  smaller, 
since  the  clitoris  is  minute  in  its  size  as  comj)ared  with  the 
organ  of  the  male. 

CLINICAL   POINTS  PERTAINING  TO  THE   PUDIC   NERVE. 

A  careful  study  of  the  distribution  of  the  various  branches 
of  this  nerve  will  show  that  it  is  the  source  of  motion  to  the 
muscles  of  the  perinseum  and  urethra,  and  of  sensation  to  the 
integument  of  the  perinseum,  scrotum,  labium,  penis,  and  the 
mucous  covering  of  the  clitoris,  as  well  as  that  lining  the 
urethral  canal.  The  friction  made  upon  the  cutaneous  nerves 
of  the  external  genital  organs  in  the  acts  of  sexual  intercourse 
and  masturbation  creates  a  reflex  act  within  the  spinal  cord, 
which  creates  the  turgidity  of  the  penis  and  clitoris  during  the 
first  portion  of  those  acts  ;  and,  later  on,  a  series  of  muscular 
€ontractions  in  the  perineal  muscles  and  the  involuntary  mus- 
cular fiber  of  the  urethral  canal  are  produced,  which  assist  in 
the  expulsion  of  semen,  in  the  male,  and  the  secretion  of  the 
glands  of  Bartholine  in  the  female.  That  this  is  the  true 
explanation  of  emission  is  evidenced  by  the  fact  that  onan- 

'  Ililton  states  that  the  integument  of  the  sides  of  the  penis  is  supplied  by  the  perineal 
branch  of  the  inferior  gluteal  nerve,  and  from  no  other  source.  This  statement  differs 
from  most  of  the  standard  authors,  but  it  seems  to  be  supported  by  clinical  demonstra- 
tion. Tlie  reader  is  referred  t9  page  752  of  this  volume,  where  the  subject  is  discussed 
from  its  physiological  and  clinical  point  of  view. 


TEE  GREAT  801  ATI G  NERVE.  765 

ism  is  most  effectually  prevented  by  blistering  the  cutaneous 
covering  of  the  penis  and  the  mucous  covering  of  the  clitoris. 

In  some  cases  of  fracture  of  the  spine,  in  the  dorsal  region, 
where  a  part  of  the  spinal  marrow  is  left  intact  below  the  seat 
of  fracture,  you  may  be  able,  by  repeatedly  pinching  the  skin 
of  the  scrotum  and  penis,  to  produce  spasmodic  contractions 
of  the  muscles  of  the  perinseum  and  urethra,  and  often  to 
effect  a  turgidity  of  the  genital  organ  to  such  a  degree  as  to 
make  it  resemble  an  imperfect  erection  or  priapism. 

The  ejaculation  of  the  last  few  drops  of  urine  from  the 
urethra  is  unquestionably  effected  by  a  reflex  act  through  the 
sensory  and  motor  fibers  of  the  pudic  nerve,  in  consequence 
of  the  irritation  produced  in  the  sensory  fibers  of  the  urethral 
mucous  membrane  from  pressure  of  the  urine  or  the  contact 
of  its  saline  ingredients. 

It  is  not  uncommon  for  rectal  disease  to  produce  sympa- 
thetic manifestations  in  the  genito-urinary  organs,  in  the  form 
of  neuralgic  pains,  involuntary  emissions,  incontinence  of 
urine,  etc.;  such  effects  can  only  be  explained  by  the  dis- 
tribution of  the  pudic  nerve  to  the  integument  about  the  anus 
(and,  I  believe,  to  the  walls  of  the  rectum  also),  which  allows 
reflex  motor  impulses  to  be  sent  from  the  spinal  cord,  in 
response  to  rectal  irritation,  to  the  genito-urinary  organs  and 
perineal  muscles. 

THE   SCIATIC  NERVE. 

This  nerve  arises  from  the  lumbo-sacral  cord  and  the  four 
upper  sacral  nerves,  and  is  a  direct  continuation  of  the  sacral 
plexus.  It  escapes  from  the  pelvis  through  the  great  sacro- 
sciatic  foramen  below  the  pyriformis  muscle,  lying  on  the 
outer  side  of  the  pudic  vessels  and  nerve.  It  then  passes 
downward  between  the  trochanter  major  of  the  femur  and  the 
tuberosity  of  the  ischium,  lying  behind  the  external  rotator 
muscles  of  the  hip  joint  and  the  adductor  magnus,  to  the 
lower  third  of  the  back  of  the  thigh,  where  it  divides  into  its 
two  terminal  branches,  the  external  and  internal  popliteal 
nerves. 


756 


THE  SPINAL  NERVES. 


In  the  lower  two  thirds  of  its  course,  it  is  covered  by  the      | 
lower  fibers  of  the  gluteus  maximus  and  biceps  muscles.     It      \ 


Fig.  229. — The  great  sciatic  nerve,  with  its  branches  of  distnbiUion  and  termination. 

(Sappey.) 
1,  superior  gluteal  nerve ;  2,  small  sciatic  nerve ;  3,  3,  3,  branches  to  the  gluteus 
maximus ;  4,  branch  to  the  pyramidalis ;  5,  internal  pudendal  branch  of  the  small 
sciatic ;  6,  femoro-popliteal  branch  of  the  same  nerve ;  7,  7,  trunk  of  the  great  sci- 
atic ;  8,  branch  which  it  gives  to  the  long  head  of  the  biceps ;  9,  branch  to  the  short 
head  of  the  same  muscle ;  10,  10,  branch  to  the  semi-tcndinosus  (the  latter  muscle 
has  been  divided  and  turned  back,  to  show  the  semi-membranosus) ;  11,  11,  branch 
to  the  semi-membranosus;  12,  12,  another  branch,  rising  from  the  common  trunk 
with  the  preceding  nerve,  and  passing  under  the  semi-membranosus  to  be  distributed 
to  the  adductor  magnus;  13,  external  popliteal  nerve;  14,  internal  popliteal  nerve; 
16,  filament  to  the  plantaris  ;  16,  16,  nerves  to  the  gastrocnemius;  17,  origin  of  the 
external  saphenous  nerve. 

gives  off  branches  to  the  hamstring  muscles  and  the  adductor 
magnus,  and  some  articular  branches  to  the  back  of  the  hip 
joint.     The  two  tables  which  I  now  show  you  are  designed  to 


DISTRIBUTION  OF  THE  SCIATIC  NERVE. 


757 


illustrate  the  branches  given  off  by  the  external  and  internal 
popliteal  nerves.  The  former  of  these  is  the  smaller  of  the  two, 
and  passes  along  the  outer  side  of  the  popliteal  space  close  to 
the  biceps  muscle,  while  the  other  traverses  the  middle  of 
the  popliteal  space  as  far  as  the  lower  border  of  the  popliteus 
muscle,  where  it  becomes  the  posterior  tibia!  nerve. 


Fig.  230. —  TJie  external  popliteal  nerve.  (Sappey.) 
1,  external  popliteal  nerve ;  2,  peroneal  or  cutaneous  branch ;  3,  communicans  peronei ; 
4,  external  saphenous  nerve  ;  5,  trunk  formed  by  the  junction  of  the  external  saphe- 
nous with  the  communicans  peronei ;  6,  calcanean  branch  rising  from  the  trunk  ; 
7,  external  terminal  branch  of  the  trunk  on  its  way  to  form  the  external  doisal 
branch  of  distribution  to  the  fifth  toe ;  8,  its  internal  terminal  branch  which  forms 
the  internal  dorsal  branch  for  the  fifth  toe  and  the  external  dorsal  branch  for  the 
fourth  toe;  9,  9,  musculo-cutaneous  nerve;  10,  10,  its  terminal  branches  ;  11,  anas- 
tomosis of  its  external  terminal  branch  with  the  external  saphenous  ;  12,  anastomosis 
of  its  internal  and  external  terminal  branches  with  each  other;  13,  anterior  tibial 
nerve ;  14,  terminal  portion  of  this  nerve,  anastomosing  with  the  musculo-cutaneous, 
and  dividing  to  form  the  deep  branches  of  distribution  on  the  dorsum  of  the  foot  tc 
the  internal  side  of  the  great  toe  and  the  external  side  of  the  second  toe. 


758 


THE  SPINAL  NERVES. 


NEKVES   OF   THE   LEG   AND   FOOT. 


(1)  Articular  branches. 

(2)  Cutaneous  branches. 


EXTERNAL 

POPLITEAL 

NERVE. 

(Peroneal 

NERVE.) 


(3)  Anterior 

Nerte. 


Tibial 


(4)  musculo-cutaneous 
Nerve. 


Three  in  number, 

Distributed  to  knee  joint. 

Two  or  three  in  number, 

Supply  integument  of  outer  and  back  part  of 

the  leg. 
Muscular  (to  muscles  in  front  part  of  leg 

and  to  the  peroneus  tertius). 
External  j  Extensor  brevis  digitorum, 
branch.    \  Articulations  of  the  tarsus. 
Internal   \  Integument  of  the  adjoining  sides 
branch.  \      of  the  great  and  2d  toes. 
,,        ,       i  Peroneus  lonaus. 
Muscular,  j  ^evoni^xxs  brevis. 

(Integument  of  outer  side  of  foot 
Extei'nal]      and  ankle, 
branch.  ]  Integument  of  the  adjoining  sides 


I 


Inte>'nal 
branch. 


INTERNAL 

POPLITEAL 

NERVE. 


(1)  Articular 


(2)  Muscular 


(3)  External  Saphe- 
nous Nerve. 


(4)  Posterior  Tibial  ^ 
Nerve. 


of  3d,  4th,  and  5th  toes 
Integument  of  the  inner  side  of 

the  foot  and  ankle, 
Integume7it  of  the  adjoining  sides 

of  2d  and  3d  toes  and  inner 

side  of  great  toe. 

Three  in  number. 

Distributed  to  knee  joint. 

Gastrocnemius, 

Plantaris, 

Soleus, 
^  Popliteus. 

'  Formed  by  two  filaments,  one  from  each  of 
the  popliteal  nerves, 

Integument  of  the  outer  side  of  foot  and  the 
little  toe. 

!  Flexor  longus  pollicis. 
Flexor  longus  digitorum, 
Tibialis  posticus. 
Plantar      j  Integument  of  heel  and  inner  part 
cutaneous.  {      of  sole  of  foot. 

^_.  .^  ,  (  Intequment  of  the 

^'f  *^    u        \      4  toes  on  inner 
branches. .  ]      ^.^^  ^^  ^^^^^  ^ 

Flexor  brevis  digi- 
torum. 
Abductor  pollicis, 
.  -l  Flexor  brevis  pol- 
licis, 
Two  inner  lumbri- 
cales  muscles. 
Articular  (to  tarsus), 
Cutaneous  (to  sole  of  foot). 

Flexor  accessorius. 
Abductor     minimi 

digiti. 
1|  outer  toes. 
Flexor  brevis  mini- 
mi digiti. 
4th      interosseous 

muscle. 

^'Sd   and   4th    lum- 

bricales, 

Rest  of  interossei. 

Adductor  pollicis, 

(^  [Transversus  pedis. 


Internal 

PLANTAR. 


External 

PLANTAR. 


Muscular 


Muscular 


• 


Superfiddl 
branch. 


branch. 


2ii 


THE  NERVES  OF  THE  LEG. 


759 


If  yon  will  study  these  tables,  you  will  perceive  tliat  the 
external  popliteal  nerve  distributes  articular  branches  to  the 


13 


Fig.  231. —  TJie  internal  popliteal  nerve.     (Sappey.) 

1,  trunk  of  the  great  sciatic  ;  2,  external  popliteal ;  3,  internal  popliteal ;  4,  4,  branches 
to  the  gastrocnemius — both  nerves  and  muscle  have  been  divided  ;  5,  origin  of  the 
external  saphenous ;  6,  branch  to  the  solcus,  divided  together  with  the  muscle  ;  7, 
internal  popliteal  nerve  passing  through  a  fibrous  ring  in  the  soleus ;  8,  8,  branch 
springing  from  the  lower  portion  of  this  nerve,  and  likewise  passing  through  the 
fibrous  ring  of  the  soleus.  At  this  level  it  gives  off  a  reflected  or  ascending  division, 
which  penetrates  the  popliteus  at  its  deep  "surface,  but  is  not  seen  in  the  cut,  and  a 
more  slender  descending  division  which  makes  its  way  through  the  interosseus  mem- 
brane and  supplies  the  tibialis  anticus  muscle  ;  9,  9,  posterior  tibial  nerve  ;  10,  10, 
branches  which  it  furnishes  to  the  flexor  longus  digitorum ;  11,  11,  branches  which 
it  gives  off  to  the  tibialis  posticus  muscle  ;  12,  12,  branches  to  the  flexor  longus  pol- 
licis ;  13,  calcanean  branches ;  14,  terminal  extremity  of  the  external  saphenous 
nerve. 

knee  joint,  and  cutaneous  filaments  to  the  outer  and  back 
part  of  the  leg.     The  two  main  nerve  trunks  which  arise  from 


760  THE  SPINAL  NERVES. 

it  are  called  the  anterior  tibial  and  the  musculo-cutaneous, 
both  of  which  are  given  off  from  the  main  trunk  after  it 
pierces  the  peroneus  longus  muscle  about  one  inch  below  the 
head  of  the  fibula,  although  three  articular  and  several  cuta- 
neous filaments  also  arise  from  it.  You  will  also  perceive 
that  four  main  branches  are  given  off  from  the  internal  pop- 
liteal nerve,  viz.,  articular  and  muscular  branches,  and  the  ex- 
ternal saphenous  and  posterior  tibial  nerves.  The  muscular 
filaments  supjply  four  muscles  in  the  immediate  vicinity  of 
the  knee,  while  the  articular  filaments,  as  in  the  preceding 
nerve,  are  distributed  to  the  knee  joint.  Other  points  of 
interest  might  be  specially  designated  as  comprised  in  these 
pages,  but  they  will  be  considered  in  their  practical  relations 
when  the  clinical  points  which  are  presented  by  the  nerves  of 
the  lower  extremity  are  considered. 

I  desire  to  call  your  attention,  first,  to  the  fascia  of  the 
leg,  into  which  three  muscles  of  the  thigh  are  inserted, 
viz.,  the  sartorius,  the  gracilis,  and  the  semi-tendinosus.  I 
have  already  called  your  attention  to  the  fact  that  the  fas- 
ciae of  the  body  are  always  to  be  regarded  as  one  of  the 
points  of  insertion  of  the  muscles  which  are  attached  to 
them ;  now,  if  this  be  true,  'and  it  undoubtedly  is  so,  we 
ought  to  discover  a  particular  distribution  of  the  cutaneous 
nerves  at  this  point,  since  the  nerves  which  supply  the  mus- 
cles supply  also  the  skin  over  the  insertion  of  the  same  mus- 
cles. We  shall  find,  on  dissection  of  this  region,  that  the 
long  saphenous,  the  obturator,  and  a  branch  of  the  sciatic 
nerves  are  distributed  in  the  skin  of  the  calf ;  the  one  de- 
rived from  the  anterior  crural  (which  supplies  the  sartorius), 
another  a  filament  of  the  obturator  (which  supplies  the  gra- 
cilis), and  the  third  derived  from  the  sciatic  (since  it  supplies 
the  semi-tendinosus  muscle).  These  three  nerves,  therefore, 
supply  both  the  fascia  of  the  leg  and  the  skin  on  the  inner 
side  of  the  leg  below  the  knee  joint ;  hence,  pain  in  this  re- 
gion must  be  sought  for  along  the  course  of  one  of  these  three 
nerves.  It  is  too  common  among  physicians  to  regard  a  pain 
which  is  localized  at  the  inner  side  of  the  knee  as  dependent 


THE  NERVES  OF  THE  LEG. 


761 


upon  the  obturator  nerve,  to  the  exclusion  of  the  sciatic  or 
the  anterior  crural ;  but  anatomy  clearly  teaches  us  that 


Fig.  232. —  The  external  saphenous  nerve  and  its  accessory,  the  communicans  peronei. 

(Sappey.) 

1,  internal  popliteal  nerve  ;  2,  nerve  to  the  external  head  of  the  gastrocnemius  ;  3,  nerve  to 
the  internal  head  ;  4,  external  saphenous  nerve ;  5,  external  popliteal  nerve ;  6, 
communicans  peronei ;  7,  peroneal  or  cutaneous  branch  ;  8,  branch  sometimes  given 
off  by  the  external  saphenous  to  the  fourth  and  fifth  toe  ;  9,  trunk  formed  by  the 
junction  of  the  communicans  peronei  with  the  external  saphenous ;  10,  calcanean 
branch  given  off  by  this  trunk  ;  11,  plantar  cutaneous  branch  of  the  posterior  tibial; 
12,  internal  saphenous  nerve  ;   13,  13,  13,  posterior  branches  of  this  nerve. 

there  are  three  possible  lines  of  direction,  which  we  are 
bound  to  explore  in  searching  for  the  situation  of  the  real 
cause  which  is  producing  it.  We  should  always  carefully 
examine  all  the  anatomical  relations  of  the  obturator,  the 
sciatic,  and  the  anterior  crural  nerves,  in  order  to  ascertain,  if 
possible,  the  real  cause  of  pain  which  is  expressed  on  the  in- 


'62 


THE  SPINAL  NERVES. 


ner  side  of  the  knee  joint,  and  the  axiom  of  nerve  distribu- 
tion, which  was  first  pointed  out  by  Hilton,  and  to  which  I 
have  frequently  directed  your  attention,  offers  us,  in  this 
instance,  as  in  many  others,  a  simple  rule  which  should 
guide  us  in  searching  for  the  cause  of  pain  before  we  attempt 
measures  for  its  relief. 


Fig.  233. —  The  plantar  nerves,  their 


anastomoses,  and  distribution.     (Sappey.) 


1,  internal  plantar  nerve  ;  2,  2,  branches  which  it  gives  to  the  abductor  pollicis  ;  3,  branch 
which  it  gives  to  the  accessorius ;  4,  branch  to  the  flexor  brevis  digitorum ;  5,  branch 
of  distribution  to  the  internal  plantar  surface  of  the  great  toe  ;  6,  another  branch  of 
the  internal  plantar  dividing  into  three  secondary  portions,  which  subdivide,  in  their 
turn,  to  form  the  branches  of  distribution  on  the  plantar  surface  to  the  outer  side  of 
the  great  toe,  both  sides  of  the  second  and  third  toes,  and  the  inner  side  of  the 
fourth  toe  ;  7,  external  plantar  nerve ;  8,  8,  branches  which  it  sends  off  to  the 
abductor  minimi  digiti ;  9,  branch  to  the  accessorius ;  10,  branch  of  distribution  on 
the  plantar  surface  to  the  outer  side  of  the  little  toe;  11,  another  branch  of  the  same 
nerve  dividing  to  supply  the  inner  side  of  the  little  toe  and  the  outer  side  of  the  fourth 
toe;  12,  anastomosis  of  the  internal  with  the  external  plantar  ;  13,  origin  of  the  deep 
branch  of  the  external  plantar. 

I  have  found,  in  several  instances,  that  local  anaesthetics, 
when  applied  to  the  skin  over  the  seat  of  pain,  frequently 
have  the  power  of  relieving  a  sense  of  distress  in  other  re- 
gions apparently  far  removed  from  it,  but  still  connected 
with  the  seat  of  pain  by  means  of  a  nervous  communication. 
Thus,  in  disease  of  the  hip  joint,  an  anodyne  applied  in  the 


CLINICAL  POINTS  AFFORDED  BY  NERVES  OF  LEG.   Y63 

region  of  the  knee  joint  will  often  relieve  symptoms  wMcli 
are  referable  to  the  hip,  and  we  can  only  attribute  this  effect 
to  a  benumbing  influence  exerted  by  means  of  the  sciatic  and 
obturator  nerves  upon  that  joint,  since  both  of  these  nerves 
send  articular  filaments  to  it,  as  well  as  cutaneous  filaments 
to  the  region  of  the  knee. 

In  some  instances,  where  abnormalities  of  origin  of  nerve 
filaments  can  be  detected,  I  believe  that,  if  you  will  trace  the 
nerve  upward  for  some  distance  toward  the  spinal  marrow, 
you  will  find  that  the  cutaneous  filaments  of  the  nerve,  which 
apparently  has  an  abnormal  origin,  are  in  intimate  communi 


Fig.  234. — The  deep  branch  of  the  external  plantar  nerve.     (Sappey.) 

1,  internal  plantar  nerve ;  2,  its  internal  branch  ;  3,  its  external  branch,  whose  two  divis- 
•ions  have  been  cut,  together  with  the  adductor  poUicis,  to  show  the  deep  branch  of 
the  external  plantar ;  4,  trunk  of  the  external  plantar ;  5,  its  superficial  branch, 
which  divides  almost  immediately  into  two  secondary  branches,  distributed  to  the 
fourth  and  fifth  toes  ;  6,  its  deep  branch,  distributed  to  the  adductor  poUicis,  trans- 
versus  pedis,  and  the  intorossei ;  7,  branches  to  the  adductor  pollicis ;  8,  8,  branches 
to  the  interossei ;  9,  branches  to  the  transversus  pedis. 

cation  with  the  nerve  trunk  whose  functions  are  assisted  by 

them,  and  from  which  its  most  frequent  origin  can  be  verified. 

If  we  examine  the  anatomy  of  the  hip  joint,  we  shall  find 


764  THE  SPINAL  NERVES, 

that  a  branch  of  the  anterior  crural  nerve  passes  in  close  rela- 
tion with  its  capsule,  if  it  is  not  intimately  associated  with 
it ;  that  a  branch  of  the  obturator  nerve  supplies  its  capsular 
ligament,  and  is  ultimately  distributed  to  the  ligamentum 
teres ;  and,  finally,  that  a  branch  from  the  sacral  plexus  sup- 
plies the  hip  joint  at  its  posterior  aspect,  after  sending  fila- 
ments to  the  gemelli,  the  quadratus  f  em  oris,  and  the  obtu- 
rator internus  muscles.  The  study  of  the  anatomy  of  joints 
is  of  particular  importance  to  the  diagnostician,  since  it  fre- 
quently explains  how  remote  sympathetic  pains  may  be 
dependent  upon  irritation  of  articular  branches  of  a  nerve, 
whose  terminal  cutaneous  filaments  are  distributed  to  other 
regions,  often  far  removed  from  the  joint  which  it  supplies. 
We  know  that  disease  of  the  hip  joint,  which  is,  perhaps, 
one  of  the  most  frequent  which  we  meet  with  in  practice,  is 
often  manifested,  in  its  early  stages,  by  a  pain  which  is  re- 
ferred to  the  knee ;  and  we  can  understand,  from  what  has 
previously  been  said,  that  this  sensation  of  pain  must  be 
transmitted  through  one  of  three  sources,  viz.,  the  obturator, 
anterior  crural,  or  the  sciatic  nerves. 

CLINICAL    POINTS    PERTAINING   TO   THE   NERVES   DERIVED    FROM   THE 
SCIATIC,    OR  TO  THE   SCIATIC   NERVE   ITSELF. 

The  morbid  conditions  of  the  sciatic  nerve  or  its  branches 
which  are  most  frequently  met  with  comprise  :  1,  neuralgia^ 
which  may  be  articular  or  confined  to  the  du*ect  course  of  the 
sciatic  nerve  ;  2,  spasmodic  affections  of  the  muscles  supplied 
by  the  sciatic  nerve  or  its  branches  ;  and  3,  paralysis  of  the 
different  muscles  supplied  by  the  various  nerve  trunks. 


SCIATICA. 

This  type  of  neuralgia^ — to  which  the  name  '*  malum  Co- 
tunnii "  is  sometimes  applied— may.  affect  the  greater  portion 
of  the  back  part  of  the  thigh,  a  part  of  the  gluteal  region,  the 
knee  joint  and  patella,  the  anterior,  lateral,  and  posterior 
surfaces  of  the  leg,  and  the  whole  of  the  foot,  with  the  excep- 


SCIATIC  NEURALGIA.  765 

tion  of  its  intemal  border,  which  derives  its  nerve  supply 
from  the  saphenous  branch  of  the  anterior  crural  nerve.  It 
is  seldom  that  all  of  these  regions  are  affected  at  the  same 
time,  since  the  nerve  may  be  subjected  to  a  source  of  irrita- 
tion which  affects  only  individual  branches.  The  most  fre- 
quent seat  of  pain  is  confined,  as  a  rule,  to  the  posterior  sur- 
face of  the  thigh  and  the  upper  half  of  the  calf  of  the  leg ; 
but  the  external  surface  of  the  lower  half  of  the  leg  and  the 
corresponding  part  of  the  foot,  as  well  as  the  sole,  are  often 
the  seat  of  a  neuralgic  pain  which  is  of  a  severe  type.  The 
disease  is  usually  unilateral  in  character,  and,  if  bilateral,  a 
central  cause  may  be  suspected. 

Among  the  causes  of  this  type  of  neuralgia  may  be  men- 
tioned exposure  to  cold  and  dampness,  malarial  affections, 
inflammations  of  the  nerve,  injuries,  pressure  of  tumors  or 
inflammatory  exudations,  violent  exertion,  disturbances  of 
the  venous  circulation  of  the  pelvis,  and  mechanical  pressure 
from  sitting  upon  hard  or  uncomfortable  seats,  uterine  dis- 
placement, pelvic  tumors,  aneurism,  and  hernia. 

The  beginning  of  this  disease  is  usually  associated  with 
premonitory  symptoms,  among  which  may  be  mentioned  a 
sensation  of  stiffness,  cold,  or  heat  in  the  affected  regions, 
with  occasional  feelings  of  formication,  or  a  fluid  trickling 
over  the  skin.  Soon  painful  electric  pains  are  experienced, 
which  show  a  marked  paroxysmal  character.  These  attacks 
occasionally  occur  without  warning  or  premonitory  symp- 
toms. The  pain  is  remarkably  violent,  and  of  a  tearing  and 
lancinating  character,  and  usually  follows  the  direction  of 
the  nerve  trunk  which  is  affected.  It  often  changes  its  seat 
of  greatest  intensity,  and  the  lines  which  connect  the  spots  of 
greatest  pain  will  generally  conform  to  the  anatomical  course 
of  the  affected  nerve.  The  pain  is  usually  markedly  increased 
by  motion  of  the  muscles,  and  the  paroxysms  seem  to  be  ex- 
cited by  the  most  trivial  causes,  such  as  a  draft  of  cold  air, 
coughing,  sneezing,  sudden  bending  of  the  body,  the  contact 
of  the  clothes  with  the  skin,  or  straining  during  the  acts  of 
defecation  or  micturition.     If  the  whole  area  of  the  distribu- 


766 


THE  SPINAL  NERVES. 


tion  of  the  sciatic  nerve  be  involved,  the  pain  occurs  with 
special  violence  first  in  one  and  then  in  another  branch,  while 
the  posterior  branches  of  the  sacral  nerves  may  be  also  impli- 
cated, and  the  patient  complain  of  violent  pain  in  the  sacrum 
and  the  loins. 


12 


Fig.  235. — TJie  motor  points  on  tJie  posterior  aspect  of  the  thigh. 
1,  branch  of  the  inferior  gluteal  nerve  to  the  gluteus  maximus  muscle ;  2,  sciatic  nerve ; 
3,  long  head  of  biceps  muscle ;  4,  short  head  of  biceps  muscle ;  6,  adductor  magnus 
muscle  ;  6,  semi-tendinosus  muscle  ;  7,  semi-membranous  muscle ;  8,  tibial  ncrre ; 
9,  peroneal  nerve;  10,  external  head  of  gastrocnemius  muscle;  11,  soleus  muscle; 
12,  internal  head  of  gastrocnemius  muscle. 


As  has  been  mentioned  in  other  forms  of  neuralgia,  certain 
painful  points  may  usually  be  detected,  which  are  diagnostic 
of  neuralgia  from  those  severe  pains  which  accompany  the 
early  stages  of  locomotor  ataxia.  The  most  constant  point  of 
sensitiveness  to  pressure  is  stated  by  Yalleix  to  correspond  to 
the  posterior  superior  spine  of  the  ilium  ;  another  usually  ex 


SPASM  OF  THE  LOWER  LIMB.  76T 

ists  where  the  nerve  escapes  from  the  cavity  of  the  pelvis ;  a 
third  is  often  found  at  the  lower  border  of  the  gluteus  maxi- 
mus  muscle,  where  the  posterior  cutaneous  branch  emerges ; 
the  fourth  corresponds  to  the  head  of  the  fibula,  where  the 
tibial  nerve  is  given  off  ;  a  fifth  point  is  often  discovered  be- 
hind the  internal  malleolus ;  and,  finally,  there  are  frequent 
inconstant  points  in  the  thigh,  on  the  calf  of  the  leg,  and  on 
the  dorsum  of  the  foot,  all  of  which  correspond  to  localities 
where  cutaneous  branches  either  divide  or  perforate  some 
fascia. 

In  connection  with  this  neuralgic  pain,  certain  motor 
symptoms  are  frequently  developed.  These  comprise  a  pe- 
culiar limping  gait,  a  mode  of  carrying  the  leg  which  is  quite 
diagnostic,  cramp  of  various  degrees,  and  possibly  convul- 
sions, which  are  sometimes  very  violent.  These  symptoms 
are  the  result  of  direct  and  reflex  irritation,  and  may  be  the 
forerunners  of  a  condition  of  paresis  or  of  actual  paralysis. 

Among  the  vaso-motor  disturbances  which  accompany  this 
disease  may  be  mentioned  paleness  and  coldness  of  the  skin, 
in  some  instances  accompanied  by  numbness  and  chilly  sen- 
sations, and  in  other  cases  redness  and  heat  of  the  skin,  with 
increased  perspiration,  increased  growth  of  the  hair,  herpes 
zoster  along  the  course  of  the  affected  nerve,  a  saccharine  con- 
dition of  the  urine,  and  hypertrophy  and  atrophy  of  the 
muscles. 

Sciatica  is  to  be  diagnosed  from  disease  of  the  hip  joint ; 
from  locomotor  ataxia  in  its  early  stages ;  from  muscular 
rheumatism  ;  and  the  pains  of  spinal  disease,  affecting  the 
lateral  columns,  when  the  patient  is  subjected  to  extreme  ex- 
ertion. 

SPASM   OF  THE   LOWER   LIMBS. 

The  muscles  of  the  hip — especially  the  psoas,  iliacus, 
quadratus  lumborum,  and  adjacent  muscles  of  the  anterior 
surface  of  the  thigh — may  be  the  seat  of  tonic  spasm,  which 
has  been  named  by  Stromeyer  *' spasmodic  contracture  of  the 
hip."  It  may  follow  an  inflammation  or  neuralgia  of  the  hip 
joint,  psoas  abscess,  or  diseases  of  the  lumbar  vertebrae.     In 


"im 


THE  SPmAL  NERVES. 


this  condition,  the  thigh  is  strongly  flexed,  the  pelvis  tilted 
upward,  and  the  limb  shortened ;  while  passive  extension 
creates  a  deviation  of  the  body  toward  the  affected  side,  and 
is  extremely  painful. 

In  rare  instances,  tonic  and  clonic  types  of  spasm  are  ob- 
served in  the  extensor  and  adductor  muscles  of  the  thigh,  as 
the  result  of  neuralgia  of  the  knee  joint  and  certain  spas- 
modic diseases  of  a  central  origin. 

The  flexor  muscles  of  the  leg  may  be  affected  with  spasms 
in  spinal  affections,  hysteria,  diseases  of  the  knee  joint,  and 
in  inflammation  of  its  adjacent  muscles. 


Fig.  236. —  The  motor  points  071  the  anterior  aspect  of  the  thigh. 

1,  crural  nerve;  2,  obturator  nerve;  3,  sartorius  muscle;  4,  adductor  longus  muscle;  5, 
branch  of  the  anterior  crural  nerve  for  the  quadriceps  extensor  muscle ;  6,  the  quad- 
riceps muscle ;  7,  branch  of  anterior  crural  nerve  to  the  vastus  internus  muscle ;  8, 
tensor  vaginae  femoris  muscle  (supplied  by  the  superior  gluteal  nerve);  9,  external 
cutaneous  branch  of  anterior  crural  nerve  ;  10,  rectus  femoris  muscle;  11,  1'^,  vastus 
externus  muscle. 

In  rare  cases,  the  anterior  muscles  of  the  leg,  which  are 
supplied  by  the  peroneal  nerve,  are  affected  with  spasms  as 


PARALYSIS  OF  SCIATIC  NERVE  OR  ITS  BRANCHES.    769 

the  result  of  exposure  to  cold  or  dampness,  over-exertion  of 
the  lower  limbs,  or  paralysis  of  the  antagonistic  muscles ; 
while  the  muscles  supplied  by  the  posterior  tibial  nerve,  as 
well  as  those  of  the  sole  of  the  foot,  are  more  frequently 
affected  as  the  result  of  spinal  affections,  joint  diseases,  over- 
exertion, paralysis  of  other  muscles,  and  by  the  reflex  action 
of  cholera. 

PARALYSIS   OF   MUSCLES   SUPPLIED   BY  THE   SCIATIC   KERVE   OR  ITS 

BRANCHES, 

When  we  consider  how  extensively  this  nerve  is  distrib- 
uted, and  its  exposed  situation  in  various  portions  of  its 
course,  as  well  as  its  intimate  relations  to  the  organs  of  the 
pelvis,  we  can  better  appreciate  the  reasons  for  the  frequency, 
on  the  one  hand,  and  the  importance,  on  the  other,  of  the 
paralysis  which  may  affect  it  or  its  branches.  Among  the 
causes  of  this  form  of  paralysis  may  be  enumerated  all  those 
conditions  of  the  trunk  which  are  capable  of  producing  press- 
ure upon  the  origin  of  the  nerve  ;  all  forms  of  accidents  which 
may  result  in  laceration  or  section  of  the  main  trunk  or  any  of 
its  branches  ;  the  development  of  tumors  in  the  course  of  the 
nerve  ;  dislocations  of  bone ;  the  compression  of  cicatrices  ; 
rheumatic  conditions,  from  chilling  or  wetting  of  the  lower 
extremities ;  surgical  operations ;  and  spinal  diseases  which 
impair  its  point  of  origin  at  the  lumbar  enlargement  of  the 
cord. 

If  t\iQ  peroneal  nerve  be  alone  affected,  the  foot  can  not  be 
flexed  or  abducted ;  neither  can  it  be  completely  addiicted. 
The  dependent  position  of  the  foot,  which  hangs  downward, 
interferes  seriously  with  the  act  of  walking,  since  the  toe 
trips  upon  every  slight  elevation. 

In  order  to  walk,  the  patient  is  compelled  to  lift  the  foot 
by  flexion  at  the  hip  joint,  and  places  it  insecurely  upon  the 
ground  with  the  outer  border  of  the  toes  first,  thus  producing 
a  gait  which  is  pathognomonic  of  this  special  type  of  paraly- 
sis. The  arch  of  the  foot  becomes  flattened  from  a  loss  of 
power  in  the  peroneus  longus  muscle  ;  the  great  toe  can  not 


770 


THE  SPINAL  NERVES. 


be  extended,  since  the  extensor  longus  poUicis  is  pamlyzed  ; 
flexion  of  the  foot  is  impaired,  since  the  extensor  communis 
digitorum  no  longer  acts ;  and  the  abduction  of  the  foot  is 
rendered  impossible,  if  the  peroneus  brevis  be  paralyzed, 
although  the  extensor  communis  digitorum  may  assist  in  this 
act  coincidentally  with  dorsal  flexion  of  the  foot. 


I 


Fio.  237. —  The  motor  points  on  the  inner  aspect  of  the  leg. 

1,  interaal  head  of  gastrocnemius  muscle ;  2,  soleus  muscle ;  3,  flexor  communis  digito- 
rum muscle  ;  4,  posterior  tibial  nerve  ;  5,  abductor  pollicis  muscle. 

If  the  tihial  nerm  be  paralyzed,  a  loss  of  power  in  the 
muscles  of  the  calf  is  indicated  by  an  inability  on  the  part  of 
the  patient  to  extend  the  foot  and  to  produce  flexion  and  a 
lateral  movement  of  the  toes.  Thus  the  patient  is  no  longer 
able  to  stand  upon  the  toes,  while,  in  consequence  of  a  sec- 
ondary contracture  of  the  muscles  situated  upon  the  anterior 


PARALYSIS  OF  SCIATIC  NEUVE  OR  ITS  BRANCHES.    771 

surface  of  the  leg,  the  foot  is  made  to  assume  a  position  which 
has  been  compared  to  the  shape  of  a  hook.  The  tibialis  pos- 
ticus muscle  no  longer  assists  in  adducting  the  foot  and  rais- 
ing its  inner  border ;  the  flexor  communis  digitorum  can  no 
longer  flex  the  two  distal  phalanges  of  the  toe,  while  paraly- 


FiG.  238. — The  motor  points  on  the  outer  aspect  of  the  leg. 

1,  peroneal  nerve ;  2,  external  head  of  gastrocnemius  muscle ;  3,  soleus  muscle ;  4,  ex- 
tensor communis  digitorum  muscle  ;  5,  peroneus  brevis  muscle ;  6,  soleus  muscle  ;  *7, 
flexor  longus  pollicis  ;  8,  peroneus  longus  muscle  ;  9,  tibialis  anticus  muscle  ;  10,  ex- 
tensor longus  pollicis  muscle;  11,  extensor  brevis  digitorum  muscle;  12,  abductor 
minimi  digiti  muscle  ;  13,  deep  branch  of  the  peroneal  nerve  to  the  extensor  brevis 
digitorum  muscle  :  14,  14,  14,  dorsal  intcrossei  muscles. 


sis  of  the  flexor  longus  pollicis  deprives  the  patient  of  the 
power  of  flexing  the  great  toe.     A  lateral  motion  of  the  great 


772  THE  SPINAL  NERVES. 

toe  is  no  longer  possible,  since  the  power  of  the  adductor  and 
abductor  poUicis  muscles  is  abolished,  while  paralysis  of  the 
interossei  muscles  (as  mentioned  also  in  connection  with  the 
hand)  renders  it  impossible  for  the  patient  to  flex  the  first 
phalanx,  or  extend  the  two  distal  phalanges  of  the  toes,  or 
separate  the  toes  from  each  other.  The  peculiar  position  of 
the  foot  which  results  from  this  paralysis  resembles  that  de- 
scribed in  connection  with  the  upper  extremity  as  the  ''  claw 
hand,"  since  the  first  phalanx  is  abnormally  extended,  the 
second  and  third  are  strongly  flexed,  the  toes  are  tightly 
compressed  together,  and  their  bulbous  ends  no  longer  touch 
the  ground.  The  weight  of  the  body  in  a  standing  position 
is  borne  upon  the  heads  of  the  metatarsal  bones.  Hence, 
some  pain  and  inconvenience  are  experienced  after  long 
standing  or  walking. 

Paralyses  of  the  sciatic  nerve  are  accompanied,  as  a  rule, 
by  disturbances  of  the  sensibility  of  the  affected  parts.  An- 
aesthesia commonly  exists  over  the  regions  supplied  by  the 
motor  nerves  to  the  muscles  which  are  paralyzed  ;  hence,  this 
symptom  may  serve  as  a  guide,  in  some  cases,  to  the  seat  of 
the  lesion  which  has  created  the  paralysis.  In  addition  to 
these  disturbances  of  sensibility,  you  may  often  notice  changes 
in  the  circulatory  apparatus  in  the  form  of  coldness  of  the 
skin,  cyanosis,  stasis  in  the  veins,  and  a  mottling  of  the  part 
with  bluish-red  streaks. 

The  trophic  disturhances  which  are  commonly  met  with 
in  severe  forms  of  paralyses  of  the  peripheral  branches  of  the 
sciatic  nerve  comprise  serious  bed-sores  on  the  heels,  ankles, 
and  over  the  sacrum ;  ulceration  of  the  skin ;  eruptions  of 
herpes  and  pemphigus ;  and,  finally,  marked  atrophy  of  the 
muscles.  When  the  sciatic  nerve  is  affected  by  a  spinal  le- 
sion above  the  cauda  equina,  the  rectum  and  bladder  are  fre- 
quently completely  paralyzed. 


lE'D  E  X 


Acervulus  cerebri,  2 1 6 

-^sthesodic  system,  599. 

systematic  lesions  of,  601. 

Ageusia,  its  tests  and  clinical  significance, 
482. 

Akinesia,  131. 

Albuminuria,  from  lesions  of  medulla,  306. 

Alveolo-condyloid  plan  of  skull,  112,  113. 

Amaurosis,  369,  372,  390. 

Amblyopia,  90,  98,  373. 

Ammon's  horn,  51,  53. 

Amygdala,  124,  125. 

Amyotrophic  lateral  sclerosis,  615. 

Anarthria,  74,  242. 

Anatomy  of  nervous  system,  extent  of  in- 
vestigations in,  4. 

Anaesthesia  of  locomotor  ataxia,  606. 

Aneurysmal  cough,  500. 

Aneurysm,  miliary,  164. 

Angular  gyrus,  93. 

Anosmia,  its  causes,  etc.,  348. 

Ansa  lenticularis,  138. 

Anterior  horn  of  spinal  cord,  cells  of,  sub- 
divisions of,  654. 

Aphasia,  71-76,  96,  97,  103. 

motor,  71,  72,  73. 

of  traumatic  origin,  120. 

sensory,  71,  73,  74,  75. 

with  hemianopsia,  200. 

Aqueduct  of  Fallopius,  423,  438. 

lesions  within,  442. 

Aqueduct  of  Sylvius,  308,  313. 

Arachnoid,  cranial,  318,  319. 

spinal,  540,  541. 

Arm,  motor  points  of  (cuts),  701,  702. 

Arnold's  nerve,  485. 

Arterial  tonus,  304. 

Artery,  carotid,  internal,  322. 

cerebral,  anterior,  322. 


Artery,  cerebral,  middle,  323. 

cerebral,  posterior,  324. 

choroid,  anterior,  322. 

choroid,  posterior,  324. 

communicating,  posterior,  323. 

ophthalmic,  322. 

vertebral,  324. 

Articulation,   impairment  of,  from  lesions 

of  pons  and  medulla,  293. 
Astigmatism,  356,  357. 
Ataxia,  changes  of  the  pupils  in,  609. 

locomotor,  602. 

"reflex  tests"  of,  609,  610. 

symptoms  of,  606,  607,  608. 

tests  for,  607,  60S,  609. 

cerebral,  with  visual  disturbance,  192, 

194. 

from  lesions  of  medulla,  307. 

Athetosis,  122. 

Auditory  nerve,  444. 

Auditory  vertigo,   its   clinical   significance, 

457. 
Auriculo-bregmatic  line,  113. 
Automatism,  cerebral  and  spinal,  42. 
Axis-cylinder  process,  550,  554. 

Basis  cruris,  37,  38,  39,  125,  201. 

Bell,  respiratory  nerves  of,  433. 

Bell's  paralysis,   426,  427,  437,  438,  439, 

440. 

its  effect  on  smell,  348. 

its   varieties,   causes,  and  symptoms, 

438,  439,  440,  441. 
Bent  arm,  its  clinical  significance,  673. 
Betz's  cells,  53,  65. 
Bladder,  its  relations  to  focal  lesions  of  the 

spinal  cord,  631. 
Blindness,  187,  188. 
psychical,  194,  195. 


774 


INDEX. 


Blood-pressure,  305. 
Blood-vessels  of  brain,  321-325. 
Boulimia,  its  clinical  significance,  503. 
Brachial  plexus,  664. 

branches  of  inner  cord  of,  669,  670. 

branches  of  outer  cord  of,  668. 

branches  of  posterior  cord  of,  670. 

communications  of,  668. 

cords  of,  664,  665,  666. 

(cuts),  665,  666. 

Brain  (see  its  various  component  parts  as 

headings). 

blood-vessels  of,  321-325. 

component  parts  of,  relative  weight  of, 

108. 

ganglia  of,  41. 

gray  matter  of,  23,  24,  25,  26,  27. 

growth  of,  107. 

membranes  of,  316-321. 

trophic  action  of,  9. 

tubular  gray  matter  of,  26. 

weight  of,  108. 

(see  also  Cerebrum,  Cerebellum,  Crus, 

Pons,  and  Medulla). 

Canal,  intestinal,  effect  of  section  of  pneu- 
mogastric  upon,  499. 

Canals,  semicircular,  446,  450, -452,  453. 

semicircular,  effects  of  section  of,  461, 

462,  463,  464. 

semicircular,  their  relations  to  audi- 
tory vertigo,  461. 

Capsule,  internal,  construction  of,  151,  152, 

153,  154. 

its  relation  to  the  thalamus,  136, 137. 

motor  and  sensory  bundles  of,  153, 

154,  158,  159. 

of  cerebrum,  151-171. 

lesions  of,  163-172. 

pressure  upon,  132. 

relations  of,  128. 

subdivisions  of,  152,  154. 

Cardialgia,  503. 

Carotid  system  of  vessels,  321. 
Caudate  nucleus,  124,  125,  126. 
Cells,  of  Betz,  53,  65. 

of  cerebral  cortex,  45,  46,  47,  48. 

of  Deiters,  551. 

of  spinal  cord,  551, 

Center,  cilio-spinal,  578. 

auditory,  71. 

cardiac,  of  medulla,  303. 

cardio-acceleratory,  298. 


Center,  cardio-inhibitory,  of  medulla,  297. 
convulsive,  of  medulla,  298. 

cortical,  for  upper  and  lower  limbs, 

subdivisions  of  (Horsley),  116,  117, 
118. 

diabetic,  297,  298. 

for  accommodation  of  vision,  175. 

for  big  toe,  65. 

for  deglutition,  297. 

for  jaw-movements,  212. 

for   movements    of    oesophagus    and 

stomach,  297. 

for  physical  evidences  of  pain,  212. 

for  vomiting,  297. 

genito-urinary,  578. 

in  medulla,  for  laughing,  sighing,  sob- 
bing, sneezing,  and  hiccoughing, 
296. 

of  Broca,  64,  65,  71,  72. 

of  Broca,  guide  to,  113,  114, 

of  hearing,  93. 

of  smell,  331. 

of  sweating,  182, 

of  vision,  91,  92, 

respiratory,  296, 

salivary,  of  medulla,  298. 

tactile,  71. 

vaso-motor,  of  medulla,  296,  304,  305. 

Centers  of  facial  movements,  subdivisions 
of  (Horsley),  116. 

of  hearing,  101. 

of  motion,  78-84. 

of   motion,   surgical  guides  to,    116, 

117,  118. 

of  smell,  101.  __ 

of  smell  and  taste,  71,  93. 

of  speech,  101,  102. 

of  touch,  101. 

of  vision,  100. 

physiological  of  medulla,  295-298, 

sensory  of  cerebral  cortex,  88-105 

vaso-motor,  9,  1 1 . 

Central  myelitis  of  spinal  cord,  624. 

Cerebellar  vertigo,  242. 

Cerebellum,  architecture  of,  216-243. 

cortex  of,  26,  219,  220,  221. 

fibers  of,  219,  221,  222,  223,  224,  225, 

226,  227. 

functions  of,  232-243. 

inferior  peduncle  of,   231,  232,  280, 

281,  286,  287. 

its  relation  to  cranial  nerves,  232. 

its  relation  to  sensory  tracts,  286. 


INDEX, 


775 


Cerebellum,  lesions  of,  234,  235,  241,  243. 

lesions  of,   symptoms  of,   241,   242, 

243. 

middle  peduncle  of,  230,  231,  290. 

peduncles  of,  219,  222,  223,  230,  231, 

290. 
processes  of,  40,  41. 

superior  peduncle  of,  128,  206,  207, 

227,  228,  229,  290. 
Cerebral  apoplexy,  163. 
Cerebral  ataxia,  with  visual  disturbance,  192. 

coma,  121. 

cortex  (see  Cortex). 

cortex,  43-106. 

cortex,  functions  of,  177,  178. 

lobes,  the  seat  of  consciousness,  22. 

softening,  163. 

topography,  surgical  bearings  of,  111- 

121. 
Cerebro-spinal  axis,  three  portions  of,  21. 

spinal  fluid,  319,  541,  542,  543. 

spinal  fluid,  movements  of,  542. 

spinal  nerves,  acts  controlled  by,  9. 

location  of,  7. 

subdivisions  of,  10. 

spinal  system,  component  parts  of,  7. 

Cerebrum,  associating  fibers  of,  30. 

asymmetry  of,  44,  45. 

basal  ganglia  of,  24. 

basal  ganglia  of,  functions  of,  66. 

base  of,  lesions  of,  97,  199. 

commissural  fibers  of,  27,  28. 

commissures  of,  314,  315,  316. 

converging  fibers  of,  28,  29. 

convolutions  of,  60-66. 

corpus  striatum  of,  24,  122. 

cortex  of,  23,  43. 

cortex  of,  lesions  of,  95,  96,  97,  98. 

cortex  of,  summary  of,  98-106. 

crus  of,  architecture  of,  38,  39,  40,  41, 

42. 

fissures  of,  57,  58,  59,  60. 

fornix  of,  fibers  of,  31. 

growth  of,  107. 

internal  capsule  of,  110,  151-171. 

internal  capsule  of,  relations  of,  128. 

lesions  of  the  interior  of,   109,  110, 

111. 

lobes  of,  57,  60,  61,  62,  63. 

lobules  of,  57,  65. 

motor  area  of,  subdivisions  of,  83,  84. 

motor  centers  of,  surgical  guides  to, 

116,  117,  118,  119. 


Cerebrum,  motor  regions  of,  77. 

non-cortical  lesions  of,  121,  122. 

occipital  convolutions  of,  91,  92. 

optic  thalamus  of,  24. 

praefrontal  lobes  of,  lesions  of,  97,  98. 

peduncular  fibers  of,  28,  29. 

projection  systems  of,  31-42. 

radiating  fibers  of,  28,  29. 

sensory  regions  of  cortex  of,  88-105. 

sinuses  of,  317,  318. 

speech  center  of,  71,  72. 

sulci  of,  guides  to,  119. 

surgical  guides  to,  111-121. 

temporal  convolutions  of,  92,  93,  94, 

95. 

weight  of,  106. 

white  matter  of,  27. 

Cervical  plexus  of  nerves,  650. 

plexus,  deep  branches  of,  655. 

plexus,  its  situation,  654. 

plexus,  superficial  branches  of,  652. 

Cheek,  hypertrophy  of,  its  causes,  419. 
Cheyne-Stokcs  respiration,  120. 
Choked  disk,  111,  120,  167,  186,  199. 
Chorda  tympani  nerve,  its  relations  to  taste, 

406. 
Choroiditis,  its  effect  on  vision,  389. 
Choreiform  movements,  following  cerebral 

lesions,  169,  170. 
Choroid  plexuses,  320,  321. 
Ciliary  muscle,  its  function  and  nerve  dis- 
tribution, 375,  378,  379. 
Cilio-spinal  center,  393,  637. 
its  relations  to  focal  lesions  of  cord, 

629. 
Cimbia,  336. 
Claustrum,  53. 
Claw-hand  deformity,  616. 
Cochlea,  450,  453. 

Coitus,  its  relation  to  spinal  disease,  633. 
its  relation  to  small  sciatic  and  pudic 

nerves,  752,  754. 
Color-blindness,  362. 
Column  of  Burdach,  sclerosis  of,  601,  602. 

of  Burdach,  557,  558,  562,  563,  564. 

of  Burdach,  synonyms  for,  557. 

of  Clarke,  554,  555. 

of  Goll,  557,  558,  562,  563,  564. 

of  Goll,  synonyms  for,  557. 

of  Goll,  sclerosis  of,  601,  602. 

of  Tiirck,  sclerosis  of,  601,  612. 

of  Turck,  557,  558,  559. 

cerebellar,  direct,  560,  561. 


776 


INDEX. 


Column,  postero-external,  561. 

postero-internal,  561. 

pyramidal,  crossed,  558,  659,  660. 

pyramidal,  direct,  558,  559,  560. 

Coma  a  symptom  of  cerebral  disease,  121. 
Commissure,  anterior  of  cerebrum,  126,  315. 
anterior  of  cerebrum,  its  relations  to 

smell,  332. 

of  spinal  cord,  537. 

posterior,  1*74. 

of  cerebrum,  211. 

of  thalamus,  138,  139. 

of  third  ventricle,  315,  816. 

Conarium,  132,  215. 
Conjunctiva,  nerves  of,  417. 
Consciousness,  loss  of,  in  cerebral  disease, 

319. 
Convolution,  sigmoid,  62,  63. 
Convolutions  of  cerebrum,  60-66. 

sensory,  of  cerebrum,  89. 

a  guide  to  trephining,  121. 

Convulsions,  with  lesions  of  pons,  293. 
Coordination,    its    relations    to    pons  and 

crus,  291. 
Cornea,  ulcerations  of,  its  relations  to  fifth 

nerve,  416. 
Comu  ammonis,  53. 
Corpora  geniculata,  132. 

quadrigemina,  110,  172-180. 

quadrigemina,  brachia  of,    135,    172, 

173. 
quadrigemina,  functions  of,  174,  175, 

176,  177. 
Corpus  album  subrotundum,  142. 

callosum,  314. 

candicans,  37,  148,  149. 

fimbriatum,  315. 

quadrigeminum,    anterior,    211,    212, 

213,214. 

striatum,  24,  122-132. 

striatum,  functions  of,  129-132. 

striatum,  a  surcingle  of,  124. 

striatum,  haemorrhage  of,  123,  124. 

striatum,  nuclei  of,  39,  122-125. 

subthalmicum,  178. 

Cortex,  gray  matter  of,  26. 

of  cerebellum,  26,  219,  220,  221. 

of  cerebrum,  23,  43-106. 

of    cerebrum,   centers   of   taste    and 

smell  of,  93. 

of  cerebrum,  color  of,  45. 

of  cerebrum,  construction  of,  44-54. 

of  cerebrum,  excitable  region  of,  99. 


Cortex  of  cerebrum,  functions  of,  55,  66, 

57,  68-105. 

of  cerebrum,  layers  of,  44. 

of  cerebrum,  sensory  regions  of,  100. 

of  cerebrum,  sensory  centers  of,  88- 

105. 

of  cerebrum,  special  types  of,  50. 

of  cerebrum,  strata  of,  46,  50,  51,  52, 

53,  54,  55. 

of  cerebrum,  strata  of,  reasons  for,  54. 

of  cerebrum,  thickness  of,  45. 

of  cerebrum,  topography  of,  57-68. 

Corti,  membrane  of,  456. 

organ  of,  447,  454,  455. 

Cortical  centers  of  hearing,  smell,  and  taste, 

75. 

centers  of  motion,  68,  69. 

centers  of  vision,  182. 

convulsions,  70,  87,  103. 

lesions,  symptoms  of,  95,  96,  97,  98. 

localization,  views  respecting,  98. 

motor  paralysis,  84,  85. 

spasm,  121. 

Cranial  nerves,  construction  of,  10. 

fibers  of,  41. 

foramina  of,  exit  of,  7. 

Crossed  paralysis,  198,  199,  200. 

Crural  neuralgia,  736. 

Crus  cerebri,  37,  38,  39,  200-216. 

fibers  of,  37. 

motor  and  sensory  tracts  of,  42. 

subdivisions  of,  37. 

Crusta  cruris,  37,  38,  39,  125,  201,  202,  203, 

204,  205. 
Cuneus,  65,  335,  336. 
lesions  of,  96,  97,  121. 

Deaf-mutism,  466. 

Deafness,  from  lesions  of  pons,  294. 

Defecation,  its  relation  to  focal  lesions  of 

the  spinal  cord,  631,  633,  638. 
Deglutition,  center  of,  reflex  acts  of,  479. 
effects  of  section  of  fifth  nerve  upon, 

406. 

excitory  nerve  of,  477. 

its  relations  to  glosso-pharyngeal  nerve, 

469. 

its  relation  to  the  otic  ganglion,  420. 

mechanism  of,  472,  473,  474,  475, 476, 

477,  478,  479. 

muscles  connected  with,  656. 

nervous  mechanism  of,  299. 

relations  of  hypo-glossal  nerve  to,  523. 


INDEX. 


777 


Deglutition,  relations   of  spinal    accessory 

nerve  to,  510. 
Delirium,  in  cortical  disease,  105. 
Dementia,  106. 

Diabetes,  from  lesions  of  medulla,  306. 
Diaphragmatic  tetanus,  662. 
Digestive  tract,  effects  of  section  of  pneu- 

mogastric  nerve  upon,  497. 
Diplopia,  its  clinical  significance,  394,  395. 
Direct  cerebellar  tract,  2*79. 
Duchenne's  disease,  395-442,  480,  524,  525. 

its  relations  to  tetanoid  paralysis,  616. 

Dura  mater,  316,  317,  318. 

spinal,  539,  540. 

Dyspncea,  its  relations  to  focal  lesions  of 

the  spinal  cord,  630. 
Dysphasia,  from  lesions  of  medulla,  307. 

Ear,  external,  447. 

internal,  450. 

internal  fluids  of,  451. 

middle,  447. 

relations  of  muscles  of,   to   hearing, 

433. 

Earache,  its  diagnostic  importance,  417. 

its  relations  to  fifth  nerve,  416. 

Eighth  nerve  (see  Nerve,  Auditory),  444. 

Elbow,  motor  centers  for,  83. 

Eleventh  nerve  (see  Nerve,  Spinal  Acces- 
sory), 505. 

Embolism,  cerebral,  72,  73. 

Ependyma,  308. 

Epilepsy,  spinal,  631. 

Equilibration,  212. 

Equilibrium,  maintenance  of,  122. 

Eustachian  tube,  function  of,  448. 

its  clinical  points  of  interest,  463, 464, 

Eye,  in  facial  paralysis,  436. 

its  relations  to  facial  diplegia,   443, 

444. 

Eyeball,  center  of  movements  of,  385. 

motions  of,   381,   382,  383,  384,  385, 

386. 

Eyelid,  effect  of  closure  of,  on  lachrymal 
apparatus,  367. 

mechanism  of  its  closure,  367. 

Eyes,  conjugate  deviation  of,  80,  169,  293. 

oscillatory  movements  of,  their  clinical 

significance,  461. 

Face,  in  facial  diplegia,  443. 

motor  centers  for,  83. 

motor  points  of  (cut),  528. 


Face,  paralysis  of  muscles  of,  437,  438,  439, 
440. 

relations  of  cervical  plexus  to  expres- 
sion of,  654. 

relation  of  facial  nerve  to  expression 

of,  435. 

spasm  of  muscles  of,  436,  437. 

Facial   centers,    subdivisions  of   (Horsley), 
116. 

Facial  diplegia,  442,  443. 

expression,  mechanism  of,  301. 

nuclei  of,  296. 

Facial  nerve  (see  Nerve,  Facial),  423. 

function  of  chorda  tympani  branch  of, 

406. 

Facial  neuralgia,  407. 

palsy,  102. 

Fallopius,  aqueduct  of,  423,  428. 

aqueduct  of,  its  relations  to  facial  pa- 
ralysis, 439,  440. 

Fascia  of  chest,  nerve  distribution  of,  654. 

of  forearm,  its  nerve  supply,  674. 

of  leg,  its  relation  to  cutaneous  nerves, 

760. 

its  nervous  supply,  733. 

Fasciculus  cuneatus,  250. 

gracilis,  250. 

rotundus,  282,  283. 

Ferrier's  visual  center,  93,  196. 

Fibers,  arcuate  of  medulla,  263. 

associating,  of  cerebrum,  30. 

associating,  of  speech,  73,  75. 

caudo-striate,  126,  127. 

commissural,  of  cerebrum,  27,  28. 

commissural,  of  spinal  cord,  584,  585. 

motor,  of  spinal  cord,  579,  580. 

of  caudate  nucleus,  126,  127. 

of  cerebellum,  219-230. 

of  cranial  nerves,  41. 

of  fornix,  31. 

optic,  deductions  respecting,  180,  181. 

peduncular,  of  cerebrum,  28,  29,  66, 

67. 

sensory,  of  spinal  cord,  580,  582,  583, 

584. 

vaso-raotor,  of  spinal  cord,  587,  588. 

Fifth  cranial  nerve  (see  Nerve,  Trigeminus), 
397. 

Fillet,  139,  207,   208,  209,  210,  283,  284, 
334. 

course  of,  277,  278,  279. 

upper,  173 

Fingers,  motor  centers  for,  83. 


7Y8 


INDEX. 


Fissure,  calcarine,  57,  GO. 

calloso-marginal,  57,  60. 

dentate,  57.  59. 

hippocampal,  57,  59. 

of  Bichat,  58. 

olfactory,  59. 

parieto-occipital,  57,  58. 

of  Rolando,  57,  58. 

of  Rolando,  guide  to  (Thane),  117. 

of  Rolando,  surgical  guides  to,   111, 

113,  114,  115. 

of  Sylvius,  57,  58. 

of  Sylvius,  surgical  guides  to,  114. 

of  Sylvius,  surgical  guides  to  (Hors- 

ley),  118. 

transverse,  57,  58. 

Fissures  of  cerebrum,  57,  58,  69,  60. 

of  spinal  cord,  537. 

Flechsig's  method  of  research,  157. 

Flocculi,  218. 

Foot-clonus,  596,  598. 

Foot,  its  attitude  in  tibial  paralysis,  771, 

772. 
Foramen  of  Magendie,  542. 
Foramina  of  Monro,  310-313. 
Forced  movements,  238,  243. 
Forearm,  motor  points  of  (cut),  703,  704. 
Formatio  reticularis,  206,  252,  274, 276,  277, 

279,  283. 
Fornix,  315,  316. 

anterior  pillars  of,  148,  149. 

body  of,  312,  315,  316. 

bulb  of,  215. 

Fourth  cranial  nerve  (see  Nerve,  Trochlea- 

ris),  395. 
Fremitus  of  fingers  in  paralytic  dementia, 

527. 
Front-tap  contraction,  598. 
Funiculus  cuneatus,  557. 
gracilis,  557. 

Gait  of  locomotor  ataxia,  607. 

of  peroneal  paralysis,  769,  770. 

of  sciatic  paralysis,  767. 

of  tetanoid  paraplegia,  616. 

Ganglia,  basal,  24. 

basal,  functions  of,  56. 

basal,  relations  of,  to  internal  capsule, 

128. 

of  brain,  41. 

of  fifth  nerve,  419,  420. 

of  fifth  nerve  (table  of),  421. 

of  origin  of  "  crusta,"  204. 


Ganglia  of  origin  of  "  tegmentum,"  206, 
210,  211,  212. 

of  visual  apparatus,  183. 

Ganglion,  ciliary,  420,  421. 

jugular,  468. 

jugular,  of  pneumogastric,  485. 

lenticular,  420,  421. 

Meckel's,  420,  421,  429,  432. 

Meckel's,  excision  of,  419. 

of  Luschka,  658. 

of  root  of  pneumogastric,  485. 

of  trunk  of  pneumogastric,  485. 

ophthalmic,  420,  421. 

ophthalmic,  its  relation  to  sixth  nerve, 

422. 

otic,  420,  421,  429,  432. 

submaxillary,  420,  421. 

of  Andersch,  468. 

of  Gasser,  475. 

of  pons,  40. 

optic,  basal,  178. 

optic,  inferior,  147. 

reticulare,  nuclei  of,  252. 

Gastric  crises,  242. 

Gelatinous  substance  of  medulla,  263. 

of  spinal  cord,  552. 

Geniculate  bodies,  135,  143,  214,  215, 
334. 

Glands,  cervical,  relations  of  their  enlarge- 
ment to  fifth  nerve,  416. 

Glieder's  members,  126. 

Globus  hystericus,  500. 

Globus  pallidus,  126. 

Glossoplegia,  524,  525. 

Glottis,  respiratory  movements  of,  510. 

Gluteal  paralysis,  747. 

Gubler,  line  of,  429,  438. 

Gudden's  method  of  research,  156,  157. 

Gyri  anectant,  62. 

operti,  65. 

Gyrus  fomicatus,  66. 

(see  Convolution). 

Habenula,  215. 

Hair,  sudden  blanching  of,  415. 

Hallucinations  of  vision,  97. 

Hand,  its  relation  to  paralysis  of  median 
nerve,  683. 

its  relation  to  paralysis  of  musculo- 
spinal nerve,  701,  702. 

its  relation  to  paralysis  of  ulnar  nerve, 

689,  690. 

motor  points  of  (cut),  703,  704. 


INDEX. 


779 


Handwriting,  its  modifications  in  paralytic 

dementia,  527. 
Head,  nerve  supply  to  posterior  portion  of, 

652,  653. 
Hearing,  effects   of  section  of  fifth  nerve 

upon,  406. 

cortical  center  of,  93. 

general  view  of  organ  of,  446. 

its  relations  to  facial  paralysis,  440. 

its  relation  to  otic  ganglion,  420. 

mechanism   of,    448,   449,    450,   453, 

454,  455,  456. 

relations  of  muscles  of  ear  to,  433. 

Heart,  acceleratory  center  of,  628,  629,  630. 

Heart,  centers  for,  in  medulla,  303. 

effects  of    section  of    pneumogastric 

upon,  497. 
Hemiangesthesia,  122,  165. 

cerebral,  193. 

cortical,  95. 

crossed,  291. 

spinal,  576. 

with  visual  disturbance,  192,  193,  194. 

Hemianopsia,  90,  198. 

deductions  respecting,  180,  181. 

homonymous,  121. 

tests  for,  188,  189,  190. 

varieties  of,  190,  191,  192. 

Hemi-chorea,  122. 
Hemiparaplegia,  634,  638. 
Hemiplegia,  164,  165. 

cortical,  95. 

spinal,  634,  636. 

with  visual  disturbance,  192. 

Hiccough,  660,661. 

its  relations  to  focal  lesions  of  spinal 

cord,  629. 
Hippocampi,  310. 
Hippocampus  major,  53,  59. 
Horsley's   guides  to  cortical  centers,  116, 

117,  118. 

subdivisions  of  motor  area,  83. 

Huguier,  canal  of,  428. 
Hypergeusia,  its  tests    and  clinical   signifi- 
cance, 481. 
Hyperopia,  its  effects  on  health,  355,  356. 
Hyperosmia,  its  causes  and  tests,  348. 
Hypoglossal  tract,  73. 
Hypophysis  cerebri,  215. 

Incoordination,  theories  of  origin  of,  611. 
Inferior  optic  ganglion,  147. 
Insular,  64,  65. 


Intercostal  neuralgia,  716. 

Internal  capsule,  lesions  of,  163-172. 

motor   and  sensory  bundles  of,    153, 

154,  158,  159. 

Interolivary  tract,  288,  584. 

Iris,  its  nervous  supply  and  movements,  376, 
377,  380,  381. 

reflex  action  of,  and  its  clinical  bear- 
ings, 381. 

relations  of  blood-vessels  to  move- 
ments, 380. 

Island  of  Reil,  64,  65. 

associating  fibers  of,  72,  73. 

Jacobson's  nerve,  471. 
Jacksonian  epilepsy,  87,  88,  96. 

Kinesodic  system,  699. 
Knee-jerk,  596,  597. 
Kopp's  asthma,  500. 

Labyrinth,  its  anatomy  and  functions,  450. 
Lachrymal  apparatus,  its  relation  to  facial 

paralysis,  444. 
Lamina,  anterior  perforated,  138. 

cinerea,  313. 

Laminae  meduUares,  210. 

Larynx,  effects  of  section  of  pneumogastric 

nerve  upon,  495. 
Lemniscus,  139,  206,  207,  208,  209,  210, 

283,  284. 

course  of,  277,  278,  279. 

Lenticular  nucleus,  124,  125,  126. 
Limbs,  centers  of  motion  of,  81,  82,  83. 
Line  of  Gubler,  293. 
Liver,  effects  of  section  of  pneumogastric 

nerve  upon,  498. 
Lobe,  prae-frontal,  76. 
Lobes  of  cerebrum,  57,  60,  61,  62,  63,  64. 
Lobule,  central,  of  cerebrum,  64. 

paracentral,  65. 

quadrate,  65. 

Local  tenderness,  as  a  guide  to  source  of 

irritation,  14. 
Locomotor  ataxia,  602. 
Locus  caeruleus,  421. 
Lumbar  plexus,  721,  722. 

tables  of  branches  of,  723,  724. 

Lumbo-sacral  cord,  744. 

Lungs,  effect  of  section  of  pneumogastric 

nerve  upon,  496. 

Macropsia,  its  clinical  significance,  388,  389. 
Macula  lutea,  351. 


780 


INDEX. 


Malum  Cotunnii,  764. 

Marafnillary  tubercle,  37. 

Mastication,  eflfects  of  section  of  fifth  nerve 
upon,  406. 

its  alteration  in  Duchenne's  disease, 

526. 

Mastodynia,  718,  719. 

Meckel's  ganglion,  420,  421. 

Median  nerve,  trophic  effects  of  paralysis 
of,  684. 

Medulla  oblongata,  accessory  nuclei  of,  265, 
266,  267. 

architecture  of,  244-307. 

arcuate  fibers  of,  285,  287. 

fibers  of,  269-290. 

fissures  of,  244,  245. 

functions  of,  294-306. 

gray  matter  of,  249-269. 

lateral  column  of,  nuclei  of,  253. 

lesions  of,  symptoms  of,  307. 

motor  and  sensory  tracts  of,  295. 

nerve  nuclei  of,  263. 

nuclei  of,  table  of,  257. 

physiological  centers  of,  295-298. 

pyramidal  tracts  of,  270,  271,  272. 

raphe  of,  fibers  of,  287. 

round  bundle  of,  282,  283. 

sensory  decussation  of,  287. 

sensory  tracts  of,  283-287. 

subdivisions  of  (Krause),  246. 

respiratory  center  of,  its  clinical  rela- 
tions, 628. 

Megalopsia,  its  clinical  significance,  388, 
389. 

Membranes,  of  brain,  316-321. 

of  spinal  cord,  539. 

Memories,  impairment  of,  in  cortical  dis- 
ease, 97. 

motor,  97. 

of  sound  and  sight  impressions,  98. 

storage    of,    in    cortical    cells,    104, 

105. 

Meniere's  disease,  366,  457. 

Meningo-encephalitis,  105,  106. 

Micropsia,  its  clinical  significance,  388, 
889. 

Mictuiition,  its  relations  to  focal  lesions  of 
the  spinal  cord,  631,  633,  638. 

Mono-ansesthesia,  96. 

Mono-paraesthesia,  96. 

Monoplegia,  85,  86,  95,  96,  165. 

its  relations  to  trephining,  120,  121. 

of  arm,  102. 


Monoplegia  of  leg,  102. 

Mono-spasm,  96. 

Motion,  cortical  centers  of,  79-84. 

Motor-nerve  fibers,  method  of  origin  and 
termination  of,  10. 

definition  of,  7. 

method  of  distribution  of,  11. 

Motor-oculi  nerve,  373. 

its  clinical  relations,  388. 

its  origin  and  course,  373,  374. 

its  relations  to  the  perception  of  dis- 
tance, 386. 

physiology   of    its    distribution,   377, 

378,  379. 

symptoms  of  paralysis  of,  391. 

Motor  points  of  upper  extremity  (cut),  701, 
702,  703,  704. 

Mouth,  changes  due  to  spasm  of,  411. 

changes  in  Bell's  paralysis,  426. 

Mouth,  motor  centers  for,  83. 

Movements  of  jaws,  center  of,  212. 

Munk's  visual  center,  197. 

Muscse  volitantes,  their  causes,  361. 

Muscle,  buccinator,  its  relations  to  degluti- 
tion, 473. 

buccinator,  physiology  of  action,  434, 

435. 

platysma,  physiology  of    its    action, 

434. 

quadriceps  extensor,  spasm  of,  734. 

stapedius,  427. 

stapedius,  function  of,  463. 

sterno-mastoid,  its  nerve  supply,  512. 

sterno-mastoid,  paralysis  of,  516,  517. 

sterno-mastoid,  tonic  and  clonic  spasm 

of,  514,  515. 

tensor  tympani,  function  of,  450,  463. 

tensor  tympani,  its  relations  to  facial 

paralysis,  440. 

trapezius,  its  nerve  supply,  512. 

trapezius,  paralysis  of,  517,  518. 

trapezius,  tonic  and  clonic  spasm  of, 

514,  515. 

Muscles,  causes  of  contracture  after  paraly- 
sis of,  632. 

extensor  and  adductor  groups  of  thigh, 

spasm  of,  768. 

flexor  group  of  foot,  spasms   of,  768, 

769. 

flexor  group  of  leg,  spasm  of,  768. 

gluteal,  paralysis  of,  747,  748. 

gluteal,  spasms  of,  747. 

of  the  hip,  spasm  of,  738,  767. 


INDEX. 


T81 


Muscles  of  the  thigh,  atrophy  of,  736, 
of  the  thigh  and  leg,  their  physiological 

groupings,  740,  741. 

■  of  the  voice,  nervous  supply  of,  509. 

Muscular  sense,  fibers  of,  683,  584. 

in  cortical  disease,  96.  » 

structures,   uses  of  nerve  connection 

between,  15. 
Myelitis,  central,  of  spinal  cord,  624, 

of  anterior  horns  of  spinal  cord,  617. 

polio-,  618. 

Myelo-brachium,  290, 
Myopia,  its  eftects,  355,  357, 

Nates  cerebri,  110,  172,  173,  175, 
Nerve,  abducens,  deep  fibers  of,  389. 
Nerve,  abducens,  421,  422. 
abducens,   clinical    relations  of,  422, 

423, 

abducens,  functions  of,  422,  423, 

accessory  obturator,  723,  724, 

accessory  obturator,  its   distributions 

and  functions,  742,  743, 

anterior  crural,  723,  724. 

anterior  crural,  its  clinical  relations, 

733. 
anterior  crural,  its  distributions  and 

functions,  730,  731. 
anterior  crural,  its  relations  to  joints, 

730,  731. 

anterior  interosseous,  668. 

anterior  tibial,  758. 

Arnold's,  485. 

auditory,  deep  origins  of,  340. 

auditory,  444. 

auditory,  anaesthesia  of,  466. 

auditory,  clinical  points  afforded  by, 

457. 

auditory,  diagram  of,  444. 

auditory,  hyperaesthesia  of,  465. 

auditory,  its  origin,  444. 

auditory,  peculiarity  of  fibers  of,  445. 

cardiac,  491. 

cell,  functions  of,  22. 

cells,   differentiation    between  motor 

and  sensory  by  their  form,  256. 

cells,  functions  of,  35. 

cervical,  clinical  points  pertaining  to, 

658, 

cervico-facial,  425,  428,  434. 

chorda  tympani,  428,  429,  480. 

chorda  tympani,  diagram  of,  429,  431. 

chorda  tympani,  function  of,  471. 

52 


648, 


rela- 


491, 


Nerve,  chorda  tympani,  its  origin,  425. 

chorda  tympani,  its  relations  to  facial 

paralysis,  439,  440. 

chorda  tympani,  its  relation  to  the  sub- 
maxillary gland,  420. 

chorda  tympani,  its  relation  to  taste, 

406. 

ciliary,  399,  400. 

circumflex,  of  arm,  664,  670,  692. 

circumflex,    of  arm,   its  clinical  rela- 
tions, 693. 

circumflex,  of  arm,  its  distribution  and 

functions,  692,  693. 

cochlear,  446. 

communicans    noni,    521,    522, 

650. 

communicans  noni,  its  surgical 

tions,  655. 

compound,  of  the  head,  418. 

cutaneous,  of  ear,  404. 

dental,  inferior,  399,  400. 

depressor,  305. 

depressor,   of  heart,  484,   485, 

509, 

depressor,  of    heart,   its  relations  to 

spinal  accessory  nerve,  511. 

descendens  noni,  521,  522, 

dorsal,  of  penis,  745, 

dorsal,   of  penis,  its  distribution  and 

functions,  753,  754, 

endings,  determined  by  shape  of  mus- 
cles, 14, 

excitory,  of  deglutition,  477- 

external   anterior   thoracic,  664,  668, 

671, 

external  cutaneous,  of  the  arm,  664, 

668,  671. 

external  cutaneous,  of  the  thigh,  723, 

724, 

external  cutaneous,  of  thigh,  its  distri- 
bution and  functions,  728,  729. 

external  popliteal,  745,  758, 

external  respiratory,  of  Bell,  664. 

external  saphenous,  758. 

facial,  423. 

facial,   clinical   points    afforded 

436. 

facial,  communications  of,  424,  425. 

facial,  course  of,  423. 

facial,  deep  origins  of,  339. 

facial,  diagram  of,  425. 

facial,  functions  of,  425,  426. 

facial,  lingual  branch  of,  428,  430. 


by, 


782 


INDEX, 


Nerve,  facial,  its  relations  to  Duchenne's 
disease,  526. 

facial,  loop  of,  in  medulla,  339. 

facial,  origins  of,  423. 

facial,  paralysis  of,  426. 

facial,  relations  to  fifth  nerve,  429. 

facial,  table  of  branches  of,  428. 

fifth,  ascending  root  of,  282. 

filaments,  distribution  of,  3. 

frontal,  399,  400. 

genito-crural,  723,  724. 

genito-crural,  its  distribution  and  clini- 
cal relations,  729,  730. 

glosso-pharyngeal,  466. 

giosso-pharyngeal,  deep  origin  of,  340. 

glosso-pharyngeal,   clinical    points  of 

interest  of,  480. 

glosso-pharyngeal,  eiFects  of  section  of, 

471. 

glosso-pharyngeal,  its  origin  and  rela- 
tions, 467. 

glosso-pharyngeal,  table  of  branches 

of,  471. 

great  auricular,  648, 649,  650,  652, 653. 

great  occipital,  648,  649,  652,  653. 

great  sciatic,  744,  745. 

great  splanchnic,  its  relation  to  pain, 

712. 

gustatory,  399,  400. 

hypoglossal,  518. 

hypoglossal,  clinical  points  pertaining 

to,  523. 

hypoglossal,  communications  of,  519, 

520,  521. 

hypoglossal,  deep  origin  of,  341. 

hypoglossal,  effects  of  section  of,  523. 

hypoglossal,  general  function  of,  518, 

522. 

impulses,  classes  of,  21. 

hypoglossal,  its  relations  to  degluti- 
tion, 473,  474,  523. 

hypoglossal,  origin  of,  518,  519. 

iliohypogastric,  723,  724. 

ilio-hypogastric,  its  clinical   relations, 

726^ 

ilio-hypogastric,  its  distributions  and 

functions,  725,  726. 

ilio-inguinal,  723,  724. 

ilio-inguinal,  its  clinical  relations,  726. 

ilio-inguinal,  its  distribution  and  func- 
tions, 725,  726. 

inferior  dental,  rules   for  section  of, 

419. 


Xerve,  inferior  gluteal,  745. 

inferior  hoemorrhoidal,  745. 

inferior  hajmorrhoidal,  its  distributions 

and  functions,  753,  754. 

inferior  maxillary,  399,  400. 

inferior  pudendal,  745. 

inhibitory,  of  vaso-motor  center,  493. 

intercostal,   physiology   of,  707,  708, 

709,  710. 

internal  anterior  thoracic,   664,   669, 

671. 

internal  cutaneous,  of  arm,  664,  669, 

684. 

internal  cutaneous,  of  the  thigh,  724. 

internal  popliteal,  745,  758. 

internal  saphenous,  724. 

Jacobson's,  471. 

lachrymal,  399,  400. 

laryngeal,  488,  489. 

lesser  internal   cutaneous,  664,    669, 

684. 

long  saphenous,  724. 

long  saphenous,  its    distribution  and 

physiology,  733. 

median,  664,  668,  677. 

median,  its  clinical  relations,  681. 

median,  its  distribution  and  functions, 

679,  681. 

median,  its  surgical  relations,  679,  684. 

middle  cutaneous,  of  the  thigh,  724. 

motor-oculi,  373. 

motor-oculi,  deep  origin  of,  336,  337, 

338. 

motor-oculi  extemus,  421,  422. 

muscular,  of  brachial  plexus,  664. 

musculo-cutaneous,  668,  671. 

musculo-cutaneous,  of  arm,  its  clini- 
cal relations,  676,  677. 

musculo-cutaneous,  of  arm,  its  physio- 
logical relations,  672,  673,  674. 

musculo-cutaneous,  of  leg,  758. 

musculo-spiral,  694,  764,  770. 

musculo-spiral,   its   clinical   relations, 

698. 

musculo-spiral,  its  course  and  distri- 

tion,  694. 

musculo-spiral,  its  cutaneous  distribu- 
tion, 697,  698. 

mylo-hyoid,  399,  400. 

nasal,  899,  400. 

nuclei  of  medulla,  254,  256,  266,  267, 

368. 

obturator,  723,  724. 


INDEX. 


Y83 


Nerve,  obturator,  its  clinical  relations,  741. 

obturator,  its  distributions  and  func- 
tions, 738,  739,  740. 

of  Wrisberg,  340. 

olfactory,  distribution    and  functions 

in  animals,  344. 

olfactory,  fibers  of,  in  brain,  329,  330, 

331,  332. 

olfactory,  341. 

olfactory  (see  Olfactory  Nerve). 

olfactory,  its  clinical  relations,  347. 

olfactory,  its  relation  to  reflex  action, 

346. 

olfactory,    structure   of   filaments  of, 

343. 

ophthalmic,  399,  400. 

optic,  349. 

optic,   causes  of    impairment   of   its 

fibers,  369,  370,  371,  372,  373. 

optic,  chiasm  of,  349. 

optic,  distribution  of,  351. 

optic,  fibers  of,  349,  350. 

optic,  fibers  of,  course  of,  333-337. 

optic,  its  association  with  fifth  nerve, 

352. 

optic,  its  clinical  relations,  368. 

optic,  its    effect   on  coordination   of 

movement,  366. 

optic,  its  effect  on  lachrymal  appara- 
tus, 366. 

optic,  its  effect  on  the  pupil,  352. 

optic,  its  relations  in  the  orbit,  354. 

optic,  its    relations    to   blood-vessels, 

354,  355. 

optic,  its  clinical  relations  to  intra- 
cerebral pressure,  369. 

optic,  its  relations  to  reflex  action,  352. 

optic,  physiological  reasons  for  pe- 
culiar distribution  of  its  fibers,  353, 
354. 

orbital,  399,  400. 

of  Wrisberg,  445,  664,  669,  710. 

patheticus,  395. 

perineal,  745. 

perineal,  its  distributions  and  func- 
tions, 753,  754. 

peroneal,  758 

phrenic,  648,  650,  664. 

phrenic,  disorders  of,  660. 

phrenic,  its  relations  to  focal  lesion  of 

spinal  cord,  628. 

phrenic,    its    surgical    relations    and 

functions,  656. 


!  Nerve,  phrenic,  physiology  of  distribution  of, 
I  656,  657,  658. 

pneumogastric,  482. 

pneumogastric,  afferent  fibers  of,  493. 

pneumogastric,  anastomoses  of,  483. 

pneumogastric,  branches  of,  486. 

pneumogastric,  clinical  points  pertain- 
ing to,  499. 

pneumogastric,  course  and  relations  of, 

494,  495. 

pneumogastric,  deep  origins  of,  340. 

pneumogastric,  diagram  of,  484,  487. 

pneumogastric,  effects  of  section  of, 

495,  496,  497,  498. 

pneumogastric,  efferent  fibers  of,  486. 

pneumogastric,  functions  of,  486. 

pneumogastric,   its    relations  to    Du- 

chenne's  disease,  526. 

portio  intermedia,  425. 

posterior  interosseous,  670,  696. 

pneumogastric,  relations  to  respira- 
tion, 493. 

posterior  thoracic,  664. 

posterior  tibial,  758. 

pudic,  744,  745. 

pudic,  its  clinical  relations,  754. 

pudic,  its  distributions  and  functions, 

»753,  754. 

pudic,  its  relations  to  the  urinary  or- 
gans and  coitus,  754,  755. 

pulmonary,    their    clinical    relations, 

501. 

radial,  670,  696. 

recurrent  laryngeal,  485. 

roots,  anterior  and  posterior  of  spinal 

cord,  fibers  of,  548,  549,  550. 

sciatic,  its  clinical  relations  and  those 

of  its  branches,  764. 

sciatic,  its  distributions  and  functions, 

755,  756,  757. 

sciatic,  paralysis  of,  or  of  its  branches, 

769,  770. 

small  sciatic,  744,  745. 

small  sciatic,  its  distribution  and  func- 
tion, 750. 

small    occipital,    648,  649,  650,  652, 

653. 

I small   sciatic,  its   relation   to  coitus, 

751,  752. 

small  sciatic,  its   relation   to   genital 

organs,  752. 

spheno-palatine,  399,  400. 

spinal  accessory,  505. 


784 


INDEX. 


Nerve,  spinal  accessory,  clinical  points  per- 
taining to,  514. 

spinal   accessory,  communications  of, 

506. 

spinal  accessory,  deep  origins  of,  341. 

spinal  accessory,  distribution  of,  507. 

spinal  accessory,  effects  of  extirpation 

of,  511. 

spinal   accessory,  .  its    communication 

with  the  suboccipital  nerve,  and  its 
physological  importance,  513. 

spinal    accessory,   its   distribution  to 

muscles,  and  its  physiological  impor- 
tance, 512. 

spinal  accessory,  its  relations  to  deglu- 
tition, 510. 

spinal  accessory,  its  relations  to  Du- 

chenne's  disease,  526. 

spinal  accessory,  its   relation   to   the 

heart's  action,  510. 

spinal  accessory,  its  relations  to  sing- 
ing, 512. 

spinal  accessory,  its  relation  to  voice, 

510. 

spinal,  roots  of,  539. 

sublingual,  518. 

suboccipital,  648,  652. 

subscapular,  664,  670,  690. 

superficial  cervical,  648,  649,  650. 

superficial  perineal,  745. 

superior  gluteal,  744,  745. 

superior  gluteal,  its  clinical  relations, 

746,  747. 

superior   gluteal,  its  distribution  and 

functions,  745,  746. 

superior  maxillary,  399,  400. 

superior  respiratory,  of  Bell,  489. 

supply  of  body,  general  rules  of,  4. 

supra-clavicular,  648,  649. 

temporal,  deep,  399,  403. 

temporo-facial,  425,  428,  434. 

temporo-malar,  309,  400. 

thoracic,  671. 

trigeminus,  397. 

trigeminus,  afferent  fibers  of,  403. 

trigeminus,   ascending    root   of,    338, 

339. 

: trigeminus,  clinical  points  afforded  by, 

407 

trigeminus,  deep  origins  of,  338,  339. 

trigeminus,  descending  root  of,  338, 

839. 

trigeminus,  diagnostic  value  of,  415. 


Nerve,  trigeminus,  diagram  of,  400. 

trigeminus,  effects  of  section  of,  405. 

trigeminus,  efferent  fibers  of,  401. 

trigeminus,    function   of   its    efferent 

fibers,  401,  402. 
trigeminus,   ganglia    connected    with, 

419. 
trigeminus,  its  relations  to  deglutition, 

474. 
trigeminus,  its  motor  and  sensory  root, 

398. 

trigeminus,  its  origin,  397. 

trigeminus,   neuralgias   of,  407,   408, 

409. 
trigeminus,  paralysis  of,  411, 412,  413, 

414,  415. 

trigeminus,  roots  of,  263. 

trigeminus,  spasms  due  to,  410. 

trigeminus,  surgical  anatomy  of,  418. 

trigeminus,  table  of  branches  of,  399. 

trochlear,  395. 

trochlear,  deep  origin  of,  337,  338. 

trochlear,  effect  of  paralysis  of,  396, 

397. 
trochlear,  its  origin  and  function,  395, 

396. 

tympanic,  425,  428. 

ulnar,  664,  669,  686. 

ulnar,  its  clinical  relations,  688. 

ulnar,  its  distribution,  686,  688. 

ulnar,  its  relations  to  focal  lesions  of 

cord,  630. 

ulnar,  its  surgical  relations,  686. 

vestibular,  446. 

Vidian,  428,  429,  432. 

Nerves,  auriculo-temporal,  399,  400. 

associated    with    vision,    lesions    of, 

182-193. 

axioms  of  distribution  of,  12,  13,  14. 

axioms  pertaining  to  distribution  of, 

12,  13,  14. 

brachial  plexus  of,  664. 

cardiac,  their  clinical  relations,  502. 

cardiac,  functions  of,  491,  492. 

cardio-acceleratory,  303. 

cardio-inhibitory,  303. 

ccrebro-spinal,  7,  9,  10. 

cervical,  641. 

cervical  (lower),  664. 

cervical  classification  of  branches,  648. 

cervical  plexus  of,  650. 

coccygeal,  642. 

cranial,  7,  10. 


INDEX, 


Y85 


Nerves,  cranial,  deep  origins  of,  329-S41. 

cranial,  relations  to  cerebellum,  282. 

cutaneous,  clinical  guides  to,  404, 405. 

cutaneous,  of  abdomen,  their  clinical 

subdivisions,  726. 

cutaneous,  of  head,  403,  404,  405. 

degeneration  of,  155,  156. 

dental,    anterior    and    posterior,    399, 

400. 

dependence  of  body  upon,  4,  5. 

distribution  of,  importance  of,  in  diag- 
nosis, 11. 

distribution  of,  11. 

dorsal,  641,  705,  706. 

dorsal,  paralysis  of,  719,  720,  721. 

dorsal,  their  clinical  relations,  710. 

dorsal,  their  communication  with  the 

sympathetic  nerve,  705. 

dorsal,  their  relation  to  the  brachial 

plexus,  705. 

dorsal,  their  relation  to  the  contents 

of  the  mediastinae  of  the  chest,  711. 

dorsal,  their  relation  to  heart  disease, 

710. 

dorsal,  their  relation  to  pleurisy,  710. 

dorso-lumbar,  708. 

from  lower  cervical  region,  663. 

gastric,  their  clinical  relations,  503. 

hepatic  of  pneumogastric,  their  clini- 
cal relations,  504. 

Intercostal,  706. 

intercostal,  lateral  and  anterior  cuta- 
neous branches  of,  706. 

intercostal,  neuralgia  of,  716,  717,  718. 

intercostal,  their  relation  to  abdominal 

pain,  713,  714. 

intercostal,  their  relation  to  disease  of 

the  digestive  viscera,  712. 

intercostal,  their  relation  to  disease  of 

the  stomach,  712. 

intercostal,  their  relations  to  focal  le- 
sions of  the  spinal  cord,  637. 

intercostal,  their  relations  to  the  pleu- 
ra, 708. 

intestinal,  of  pneumogastric,  their  clin- 
ical relations,  504, 

laryngeal,  their  clinical  relations,  500. 

lumbar,  641,  722. 

motor,  7,  10. 

oesophageal,  497. 

of  arm  and  forearm  (tables  of),  G68. 

of  hip  joint,  763,  764. 

of  larynx,  489,  490. 


Nerves  of  leg  and  foot  (table  of),  758. 

of  pia  mater,  320,  321. 

of  respiratory  movements  of   glottis, 

489. 

of  skin,  relation  to  muscles  and  joints, 

4. 

petrosal,  425,  428,  429,  430,  432. 

petrosal,  diagram  of,  432. 

petrosal,  their  relations  to  facial  pa- 
ralysis, 439,  440. 

plantar,  758. 

resection  of,  rules  for,  418. 

respiratory,  of  Bell,  433. 

sacral,  641,  743. 

sacral,  neuralgia  of  posterior  branches 

of,  766. 

sensory,  7,  10. 

spinal,  10. 

spinal,  axioms  of  distribution  of,  644, 

645,  646. 

subscapular,  distribution  of  each,  690. 

subscapular,    their  clinical   relations, 

691,  692. 

superior  maxillary,  rules  for  excision 

of,  419. 

supra-orbital,  399,  400. 

supra-orbital,   rules    for    division  of, 

418,  419. 

supra-scapular,  664. 

sympathetic,  7. 

thoracic  intercostal,  706. 

thoracico-abdominal  intercostal,  706. 

to  the  peritonaeum,  and  their  physiol- 
ogy, 727. 

trochlear,  399,  400. 

vaso-motor,  10. 

vaso-motor  of  medulla,  304,  305. 

vasomotor  of  spinal  cord,  692,  593. 

Nervous  system,  component  parts  of,  5. 

histological  elements  of,  21. 

methods  of  studying,  15,  16. 

Neuralgia,  cervico-occipital,  659. 

diaphragmatic,  660. 

intercostal,  716,  717,  718. 

of  anterior  crural  nerve,  736. 

of  the  ilio-hypogastric  and  ilio-ingui- 

nal  nerves,  725,  726. 

of  the  mammary  gland,  718. 

of  the  obturator  nerve,  741. 

of  the  phrenic  nerve,  660. 

of  the  phrenic  nerve,  its  differential 

diagnosis,  661. 

of  the  sciatic  nerve,  764,  765,  766,  767. 


786 


INDEX. 


Neuroglia  of  cerebral  cortex,  4Y,  48. 

of  spinal  cord,  551,  552. 

Neuro-retiniti?,  Ill,  186. 

Ninth  nerve,  466. 

Nuclear  formation,  265. 

Nuclei,  acoustic,  functions  of,  296. 

of  auditory  nerve,  340. 

accessory,  of  medulla,  265-26Y. 

acoustic,  266,  26*7. 

facial,  accessory,  functions  of,  296. 

of  trigeminal  nerve,  338,  339. 

red,  132. 

Nucleus,  accessory  hypo-glossal,  functions 

of,  296. 

caudate,  124,  125,  126. 

caudate,  construction  of,  126. 

caudate,  fibers  of,  126,  127. 

clavate,  225,  250,  251,  268,  282,  285. 

dentate,  226. 

emboliformis,  218. 

facial,  inferior,  266. 

fastigii,  218,  219. 

globosus,  218. 

gray,  of  Meynert,  124. 

hypoglossal,  accessory,  266. 

lenticular,  fibers  of,  125. 

lenticular,  internal  capsule  of.  151. 

lenticular,  89,  124,  125,  126. 

lenticular,  subdivisions  of,  126. 

of  motor  oculi  nerve,  262. 

red,  of  the  tegmentum,  215,  223,  226, 

227,  267,  290. 

spinal  accessory,  266. 

of  third  nerve,  subdivisions  of,  337. 

triangular,  226,  250,   251,  267,   268, 

282,  285. 

yellow,  of  Luys,  126,  237. 

Nystagmus,  its  clinical  significance,  392. 

Obturator  neuralgia,  741,  742. 

paralysis,  742. 

Olfactory  bulb,  330. 

nerve,  roots  of,  331. 

nerve  (see  Nerve,  Olfactory). 

Olivary  body,  251,  268,  269,  276,  288. 

hilus  of,  268. 

peduncle  of,  268. 

Ophthalmoplegia,  externa,  338. 
Optic  apparatus,  lesions  of,  182-193. 

commissures  of,  138,  139. 

fibers,  decussation  of,  334,  336. 

fibers  related  to,  139,  140. 

functions  of,  140-147. 


Optic  ganglia  of  Luys,  142,  143. 

Optic  thalamus,  its  arch-like  shape,  133, 

thalamus,  24,  132-147. 

its  general  relations,  133,  134. 

its  relations  to  automatism,  147. 

its  relations  to  hallucinations,  143. 

its  relations  to  internal  capsule,  136, 

137. 

its  relation  to  special  senses,  143,  144. 

lower  peduncle  of,  138. 

Optic  lobes,  172. 

nerve  (see  Nerve,  Optic). 

nerves  and  tracts,  183. 

tract  of  Wernicke,  137. 

surfaces  of,  135,  136,  137. 

tubercles  of,  134,  135. 

Pain,  a  guide  to  cortical  lesions  of  cere- 
brum, 95. 

appreciation  of,  by  pons,  293. 

at  knee  joint,  its  clinical  significance, 

734,  740,  760,  761,  762. 

facial,  of  Fothergill,  407. 

in  the  back,  its  relation  to  aneurism, 

713. 

in  the  pectoral  region,  its  clinical  sig- 
nificance, 713. 

in  the  penis,  its  clinical  significance, 

762. 

in  the  pit  of  the  stomach,  its  clinical 

significance,  712. 

in  the  region  of  the  thorax,  its  diag- 
nostic value,  710,  711,  712. 

in  the  shoulder,  its  relation  to  diseases 

of  the  liver,  714. 

in  the  thorax,  its  relation  to  gastric 

and  intestinal  disease  and  tumors  of 
the  viscera,  714. 

its  relation  to  the  phrenic  nerve,  657. 

of  gout,  604. 

of  locomotor  ataxia,  its  diagnostic  pe- 
culiarities, 603. 

of  rheumatism  of  muscles,  605. 

spinal  transmission  of,  576. 

Palate,  its  relation  to  deglutitien,  477. 

its  relations  to  facial  paralysis,  440. 

its  relations  to  glossopharyngeal  nerve, 

468. 

nerves  of,  431. 

Papilla  of  retina,  351. 

Paralysis  alterne,  291. 

atrophic,  spinal,  617. 

bulbar,  300,  524,  625. 


INDEX. 


787 


Paralysis,  bilateral,  of  face,  442. 

cortical,  localization  of,  102,  103. 

crossed,  198,  199,  200,  423,  428,  438. 

crossed,  varieties  of,  192,  193,  291. 

due  to  crutches,  705. 

due  to  lead-poisoning,  699,  700,  701. 

facial,  437,  438,  439,  440. 

facial,  crossed,  291,  292. 

facial,  crossed,  428, 429,  430,  438,  439. 

glosso-labio-laryngeal,  480,  524,  525. 

motor  or  sensory,  from  lesions  of  me- 
dulla, 306. 

of  anterior  crural  nerve,  735,  736. 

of  Bell,  426,  427. 

of  circumflex  nerve  of  shoulder,  693, 

694. 

of  cortical  origin,  84. 

of  diaphragm,  660,  662. 

of  dorsal  nerves,  719,  720,  721. 

of  Duchenne,  444,  524,  525. 

of  median  nerve,  681,  682,  683. 

of  muscles  of  the  back,  720,  721,  722. 

of  musculo-cutaneous  nerve,  676. 

of  musculo-spiral  nerve,  698,  699,  700, 

701,  702. 

of  obturator  nerve,  741,  742. 

of  ocular  muscles,  its  causes,  393,  394. 

of  peroneal  nerve,  769. 

of  sciatic  nerve,  767,  769. 

of  sciatic  nerve,  its  sensory  disturb- 
ances, 772. 

of  sciatic  nerve,  its  trophic  disturb- 
ances, 772. 

of  superior  gluteal  nerve,  747. 

of  the  insane,  106,  106. 

of  the  insane,  527. 

of  the  ocular  muscles,  its  effect  on  the 

position  of  the  head,  386,  387,  388. 

of  tibial  nerve,  770,  771. 

of  tongue,  529. 

of  trigeminus,  from  lesions  of  pons, 

293. 

of  ulnar  nerve,  688,  689,  690. 

spastic  spinal,  615. 

spinal,  586. 

tetanoid,  615. 

tetanoid,  gait  of,  616. 

tetanoid,  its   relations  to  Duchenne's 

disease,  616. 

Paralytic  dementia,  527. 

rigidity,  85,  86. 

Paraphasia,  74,  96,  97. 

Paraplegia,  hemi-,  634,  638. 


Paraplegia,  tetanoid,  615. 

Paresis,  general,  106. 

Parolivary  bodies,  269. 

Patheticus  nerve,  396. 

Peduncular  tract,  transverse,  of  Gudden, 
336. 

Peduncle,  inferior,  of  cerebellum,  231,  232. 

middle  of  cerebellum,  230,  231. 

superior,  of  the  cerebellum,  227,  228, 

229. 

Peduncles  of  cerebellum,  219,  222,  223. 

Pia  mater,  cranial,  319,  320. 

spinal,  540. 

Pineal  gland,  132,215. 

Pituitary  body,  243,  244. 

Pleurodynia,  its  diagnosis  from  pleurisy  and 
angina  pectoris,  718. 

Point  apophysaire,  409. 

Polio-myelitis,  its  causes,  varieties,  and 
symptoms,  618,  619,  620. 

Polydipsia,  its  clinical  significance,  503. 

Polyphagia,  its  clinical  significance,  504. 

Pons  Varolii,  architecture  of,  244,  307. 

cells  and  fibers  of,  40. 

gray  matter  of,  226. 

gray  matter  of,  249-269. 

fibers  of,  245,  246. 

arrangement  of,  40. 

functions  of,  41,  291-296. 

haemorrhage  of,  294. 

Ponti  brachium,  290. 

Posterior  longitudinal  fasciculus,  148,  206, 
207,  276. 

Post-paralytic  rigidity,  104. 

Post-pedunculus,  290. 

Praepedunculus,  290. 

Process  of  Lenhossek,  561. 

Progressive  muscular  atrophy,  620. 

Projection  systems  of  cerebrum,  31-42. 

of  Meynert,  31,  32. 

of  Spitzka,  32,  33,  34,  35. 

Prosopalgia,  its  clinical  significance,  407. 

Psychical  blindness,  194,  195,  196,  197. 

Pterion,  U8. 

Ptosis,  391. 

Pulvinar  of  thalamus,  136,  143,  334. 

Puncta  dolorosa,  of  cervico-occipital  neural- 
gia, 659. 

of  crural  nerve,  736. 

of  fifth  nerve,  409. 

of  intercostal  nerve,  718. 

of  lumbar  nerves,  726. 

of  phrenic  neuralgia,  660. 


Y88 


INDEX. 


Puncta  dolorosa  of  sciatic  nerve,  766. 

Pupil,  changes  in,  and  their  physiology, 
360. 

mechanism  of  its  contraction  and  dila- 
tation, 376,  377,  380,  381. 

Pupils,  contraction  of,  a  symptom  of  lesions 
of  pons,  294. 

Robertson's,  381. 

Pupillary  movements,  212. 

Puskinje's  cells,  220. 

Pyramidal  fibers,  decussation  of,  251. 

tracts,  202,  203,  270,  271,  272. 

accessory  fibers  of,  272,  273. 

Reflex,  abdominal,  596. 

Achilles,  597. 

cremasteric,  596. 

epigastric,  596. 

gluteal,  596. 

deep,  596,  597,  698. 

patellar,  596,  597. 

peroneal,  596,  598. 

plantar,  596. 

scapular,  596. 

skin,  595,  596. 

spinal,  595,  598. 

superficial,  595. 

Respiration,  center  of,  relations  of,  to  vaso- 
motor center,  305,  306,  628. 

its  effects  on  cerebro-spinal  fluid,  642, 

543. 

nervous  mechanism,  301,  302. 

Respiratory  bundle  of  Krause,  282. 

mechanism,  in  medulla,  301,  302. 

Restiform  body,  222,  286,  287. 

fibers  of,  289. 

Reticular  formation,  its  relations  to  sensory 
tracts,  293. 

ganglion,  33,  34. 

process,  555. 

Retina,  blind  spot  of,  361. 

construction  of,  363. 

papilla  of,  351. 

Rigidity,  post-paralytic,  104, 

Robertson's  pupil,  381, 

Rolando's  fissure,  57,  58. 

Rotary  movements,  243. 

Round  bundle  of  medulla,  282,  283. 

Saccule  of  the  labyrinth,  446,  452. 
Sacral  plexus,  743, 

articular  branches  of,  744,  745. 

muscular  branches  of,  744,  746, 


Sacral  plexus,  muscular  branches  of,  their 

distribution  and  function,  748,  749, 

750, 

table  of  its  branches,  744. 

Salaam  convulsions  of  Newnhara,  516. 
Salivary  secretion,  effects  of  section  of  fifth 

nerve  upon,  406. 
Scalp,  pain  of,  its   diagnostic  importance, 

417. 
Sciatic  neuralgia,  764,  765,  766,  767. 
Second  cranial  nerve,  349, 
Sensory  nerves,  definition  of,  7. 
method  of  origin  and  termination  of 

10. 
Sensory  tract,  206,  207. 
Sensory  tracts,  89,  90. 

of  cord,  560,  561,  562,  663. 

Septum  lucidum,  309. 

Seventh  cranial  nerve  (see  Nerve,  Facial), 

423. 
Shoulder,  motor  centers  for,  83. 
Sight,  effects  of  section  of  fifth  nerve  upon, 

406. 
lesions   causing  impairment  of,   184, 

185. 
Singing,  its  alteration  in  Duchenne's  disease, 

526. 
relations  of  spinal  accessory  nerve  to, 

512. 
Sixth  cranial  nerve  (see  Nerve,  Abducens), 

421. 
Skin,  nerves  of,  relations  of,  to  muscles  and 

joints,  4. 
Smell,  center  of,  331. 

cortical  center  of,  93. 

Smell,  effect  of  fifth  nerve  upon,  344. 
effects  of  section  of  fifth  nerve  upon, 

406. 

its  modifications  and  their  causes,  345, 

its  alterations  in  Bell's  paralysis,  348. 

its  modifications  in  animals  and  races, 

344. 

its  relations  to  taste,  347. 

physiology  of  its  production,  344, 

relations  of  act  of  sniffing  to,  433. 

relations  of  the  facial  nerve  to,  433. 

tests  for,  347,  848. 

Sneezing,  its  physiology,  345. 

Sommering,  yellow  spot  of,  351. 

Space,  posterior  perforated,  200. 

Spasm  of  diaphragm,  due  to  phrenic  nerve, 

660,  662. 
of  gluteal  muscles,  747. 


INDEX, 


789 


Spasm  of  loweT  limbs,  767. 

of  muscles  of  the  hip,  738. 

of  quadriceps  extensor  muscle,  734. 

of  stcrno-mastoid  and  trapezius  mus- 
cles, 615,  516. 

of  tongue,  529. 

Spasmodic  contraction  of  the  hip,  767. 

tabes,  615. 

Special  senses,  impairment  of,  from  lesions 
of  internal  capsule,  166,  167,  168. 

Speech,  disturbances  of,  71,  73-76. 

its  alterations  in  Duchenne's  disease, 

525. 

its  modifications  in  paralytic  dementia, 

527. 

muscles  connected  with,  656. 

tract,  73,  74,  75,  293. 

Spider-cells,  551. 

Spina  bifida,  542. 

Spinal  automatism,  568,  570,  579,  580. 

canal,  535. 

cells,  550,  551. 

automatic  action  of,  592,  593,  594. 

centers,  578,  579. 

epilepsy,  631. 

hemiplegia,  634,  636. 

Spinal  cord,  aesthesodic  system  of,  599. 

an    organ   of    conduction,    574,    575, 

576. 

an  organ  of  coordination,  579. 

anterior  root  zone  of,  560. 

architecture  of,  533,  573. 

arrangement  for  protection  of,  536. 

as  a  nerve  center,  590-599. 

blood-vessels  of,  643,  544. 

central  canal  of,  555,  656. 

central  myelitis  of,  624. 

classification  of  diseases  of,  601. 

clinical  points  pertaining  to,  599. 

columns  of,  668-566. 

columns  of,  development  of,  563,  564, 

565. 

consisting  of,  535. 

degeneration  of  the   cells  of  anterior 

horns  of,  620. 

dentate  ligament  of,  535. 

descending  degeneration  of,  570,  572; 

enlargements  of,  cervical  and  lumbar, 

636. 
fibers  of,  579,  580,  582,  583,  584,  585, 

586,  587,  589. 

fibers  of,  arrangement  of,  675. 

fibers  of,  general  course  of,  573,  574. 


Spinal  cord,  fibers  of,  secondary  degenera- 
tion of,  563,  664. 

fibers  of,  varieties  of,  647,  548. 

fissures  of,  537. 

focal  lesions  of,  625. 

focal  lesions  of,  above  lumbar  enlarge- 
ment, 632. 

focal  lesions  at  lumbar  enlargement 

of,  633. 

focal  lesions  of,  cervical  enlargement 

of,  628. 

focal  lesions  of  lateral  half  of,  634. 

focal  lesions  of  mid-dorsal  region  of, 

631. 

focal  lesions  of  upper  cervical  regions 

of,  628. 

functions  of,  566,  598. 

gelatinous  substance  of,  652. 

gray  commissure  of,  566. 

gray  matter  of,  551-560. 

gray  matter  of,  Spitzka's  subdivisions, 

264. 

histological  elements  of,  547-552. 

horns  of,  553,  554. 

inhibitory  fibers  of,  561,  562. 

kinesodic  system  of,  599. 

lateral  column  of,  560. 

length  of,  533. 

localization  of,  functions  of,  690. 

membranes  of,  539. 

motor  cells  of,  654. 

motor  tracts  of,  558,  559,  560. 

myelitis  of  anterior  horn,  617. 

neuroglia  of,  551,  552. 

non  -  systematic  or  focal  lesions   of, 

600,  601,  625. 

paths  of  transmission  of,  585. 

sclerosis  of,  lateral  columns  of,  615* 

segments   of,  individual  functions  of, 

588,  589. 

sensory  columns  of,  561-564. 

sensory  conduction  of,  paths  of,  672. 

sudorific  fibers  of,  561. 

systematic  lesions  of,  699,  601. 

systematic  lesions  of,  aesthesodic  sys- 
tem of,  601.  ' 

systematic  lesions  of,  kinesodic   sys- 
tem of,  611. 

transverse  section  of,  552-566. 

transverse  section  of,  varying  shapes 

of,  536. 

trophic  action  of,  9. 

j  trophic  function  of,  577. 


•90 


TKDEX. 


Spinal  cord,  vaso-motor  centers  of,  637. 

white  commissure  of,  556. 

Spinal  nerves,  641. 

nerves,  roots  of,  641,  643. 

nerves,  definition  of,  10. 

Spinal  nerve  roots,  anterior  and  posterior 

fibers  of,  548,  549,  550. 

paralysis,  atrophic,  61Y. 

Spinal  reflex  action,  567,  568. 
Spinal  reflexes,  595,  596,  597,  598. 
Spinal  segment,  539. 
Spinal  segments,  566,  567. 

guides  to,  544-547. 

Spinal  tracts,  569,  571. 

decussation  of,  672. 

Splenium,  314, 

Stephanion,  118. 

Stomach,  effects  of  section  of  pneumogas- 

tric  upon,  498. 
Strabismus,  internal,  its  clinical  significance, 

392,  395,  422. 
Stratum  cinereum,  173. 

glomerulosum,  330. 

intermedium,  202. 

lemnisci,  173. 

opticum,  173. 

Stratum  zonale,  133. 

Stria  cornea,  66,  67,  127. 

Sub-arachnoidean  space,  319. 

Sub-dural  space,  319. 

Subicular  region,  62,  63. 

Substantia  innominata  of  Reil,  138,  148. 

nigra,  201,  204,  205. 

Sulci,  guides  to,  119. 
Sulcus,  oculo-motori,  201. 
Superior,  olive,  267,  269. 
Surcingle  of  corpus  striatum,  124. 
Surgical,  guides  to,  cerebrum,  111-121. 
Suture,  coronal,  its  relations  to  Rolando's 

fissure,  111,  112. 
lambdoidal,  its  relation  to  parieto-oc- 

cipital  fissure,  112,  113. 
squamo  -  parietal,    a    surgical    guide, 

118. 
Sylvian  fissure,  57,  58. 
Sympathetic  nerve,  as  a  regulator  of  the 

vascular  supply  of  tissues   and  or- 
gans, 9. 

parts  of,  7. 

parts  supplied  by,  7,  8. 

System,  carotid,  321. 

vertebral,  321. 

Systems,  projection,  81-42. 


Taenia,  semi-circularis,  142. 
Taste,  anaesthesia  of,  482. 

buds,  471,  472. 

cortical  center  of,  93. 

effect    of    chorda-tympani    nerve   on, 

406. 

effects  of  nerves  upon,  471. 

effects  of  section  of  fifth  nerve  upon, 

406. 

hyperaesthesia  of,  481. 

its  clinical  relations,  481. 

its  relations  to  facial  paralysis,  439 

its  relations  to  glossopharyngeal  nerve, 

470. 

limits  of  its  situation,  472. 

Teeth,  chattering  of,  in  spasm,  410. 

grinding  of,  in  spasm,  410. 

Tegmenta,  brachium,  290. 

Tegmentum   cruris,    37,  38,  39,  140,    201, 

205,  206,  207,  208. 

ganglia  of,  132. 

Temperature,  in  cerebral  diseases,  170. 
Temperature  of  the  body,  its   relations  to 

focal  lesions  of  the  cord,  630. 
Tendo-oculi,  its  function,  367. 
Tendon,  reflexes,  596,  597,  598. 
Tenth  cranial  nerve  (see  Nerve,  Pneumogas- 

tric),  482. 
Testes  cerebri,  172,  173,  175,  212. 
Tetanoid  paraplegia,  615. 
Thalmencephalon,  132. 
Third  cranial  nerve  (see  Nerve,  Motor-oculi), 

373. 
Tic-douloureux,  407. 
Thumb,  motor  centers  for,  83. 
Titubating  gait,  242. 
Tongue,  fibrillary  tremor  of,  529. 
furring  of,  its  clinical  significance,  416 

470. 

its  relations  to  deglutition,  473,  475. 

loss  of  power  of,  protrusion  of,  307. 

nerves  of,  522,  523. 

paralysis  of,  529. 

spasm  of,  529. 

Tonsillae,  218. 

Touch,  cortical,  center  of,  94. 

impressions,  transmission  of,  583. 

Tremor,  in  cerebral  disease,  122. 
Trephining,  rules  for,  employment  of,  119, 

120,  121. 
Trigeminus  nerve  (see  Nerve,  Trigeminus). 
Trineural,  bundle  (Spitzka),  287. 
Trochlear  nerve,  395. 


INDEX. 


Y91 


Trochlear  nerve,  effect  of  paralysis  of,  396, 
397. 

its  origin  and  function,  395,  396. 

Tubercle  of  Rolando,  283,  338,  5.^2. 
Tubular,  gray  matter,  26,  33,  41,  42,  147- 

150. 
Tumors,  cerebral,  their  symptoms,  410. 
Tiirck's  method  of  research,  155,  156. 
Twelfth  cranial  nerve   (see   Nerve,   Hypo- 
glossal), 518. 

Uncus,  66. 
Utricle,  452. 

Vallecula,  216. 

Valve  of  Vieussens,  fibers  of,  41. 

fibers  of,  229. 

Vaso-motor  centers,  situation  of,  9. 
Vaso-motor  fibers  of  fifth  nerve,  409. 

nerves,  subdivisions  of,  10. 

symptoms,  from   lesions   of  medulla, 

367. 
Velum,  interpositum,  312,  320. 
Ventricle,  fifth,  309. 

fourth,  313,  314. 

fourth,  formation  of,  247,  248. 

fourth,  haemorrhage  into,  294. 

fourth,  nuclei  of,  254,  255,  256,  257, 

258. 

lateral,  308,  310,  311. 

of  brain,  307-314. 

third,  312. 

third,  commissures  of,  312,  313. 

third,  gray  matter  of,  147-150. 

vessels  of,  325. 

Ventricular,  terminalis,  556. 
Vermiform  process  of  cerebellum,  216. 


Vertebrae,  spines  of,  guides  to,  spinal  seg- 
ments, 544-547. 

Vertebral  system  of  vessels,  34. 

Vesicular  column  of  Clarke,  264,  265,  279, 
282. 

Vestibule  of  labyrinth,  446,  450. 

Vicq  de  Azyr,  bundle  of,  149. 

Vision,  accommodation  of,  378. 

Vision,  apparatus  of,  lesions  of,  184-193. 

center  of,  91,  92,  196. 

deceptive,  its  clinical  significance,  388. 

determination  of  distance,  386. 

its  abnormalities  and  their  conse- 
quences, 355,  356. 

perception  of  color,  362,  364,  365. 

physiology  of  light-sensations,  361. 

tests  for,  358,  359. 

Visual  field,  335. 

fields  for  colors,  197,  198. 

Visual  purple,  362. 

spheres  of  Munk,  334. 

Vocal  cords,  motor  centers  for,  83. 

Voice,  its  relations  to  facial  diplegia,  443. 

nervous  supply  of  muscles  of,  509. 

relations  of  spinal  accessory  nerve  to, 

510. 

Vomiting,  in  brain  diseases,  120. 

Vomiting,  nervous,  504. 

Waller's  axiom,  156. 

Waller's  method  of  research,  155,  156. 

Weight,  of  component  parts  of  brain,  108, 

109. 
Word-blindness,  74,  96,  97. 
Word-deafness,  73,  74,  75,  96,  97. 
Wrisberg,  nerve  of,  423,  425. 
Wrist,  motor  centers  for,  83. 


THE  END. 


May,  1888. 


MEDICAL 


AND 


HYGIENIC    WOEKS 


PUBLISHED   BY 


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Medical  Literature.     8vo.     {In  press.) 

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CARTER  (ALFRED  H.).  Elements  of  Practical  Medicine.  Third  edition,  re- 
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CHAUVEAU  (A.).  Tiie  Comparative  Anatuniy  of  the  Domesticated  Animals. 
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FLINT  (AUSTIN,  Jr.).  Text-Book  of  Human  Physiology;  designed  for  the 
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i 


3 

FLINT  (AUSTIN,  Jr.).  The  Source  of  Muscular  Power.  Arguments  and  Con- 
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FOTHERGILL  (J.  MILNER).  Diseases  of  Sedentary  and  Advanced  Life. 
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late<l  from  the  fourth  German  edition  by  Arthur  E.  J.  Barker,  M.  D.,  and 
revised  by  the  author.  With  608  Engravings  on  Wood.  8vo.  Cloth,  $5  00; 
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GYNAECOLOGICAL  TRANSACTIONS.     8vo.     Cloth,  per  volume,  $5.00. 

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American  Gynaecological  Society,  held  in  Chicago,  Septem 
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American  Gyna3cological  Society,  held  in  Washington,  D.  C. 
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Ameiican  Gynaecological  Society,  held  in  New  York,  Tues- 
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1887. 


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edition,  rewritten,  enlarged,  and  improved.    8vo.    Cloth,  $5.00;  sheep,  $6.00. 

HAMMOND  (W.  A.).  A  Treatise  on  Insanity,  in  its  Medical  Relations.  8vo. 
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HAMMOND  (W.  A.).  Clinical  Lectures  on  Diseases  of  the  Nervous  System. 
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M.  D.     8vo.     Cloth,  $3.50. 

HARVEY  (A.).     First  Lines  of  Therapeutics.     12mo.     Cloth,  $1.50. 

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Vienna.     Second  enlarged  and  improved  edition.     8vo.     Cloth,  $2.00. 

HOWE  (JOSEPH  W.).  Emergencies,  and  how  to  treat  them.  Fourth  edition, 
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HOWE  (JOSEPH  W.).  The  Breath,  and  the  Diseases  which  give  it  a  Fetid 
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and  Keyes.  Almost  entirely  rewritten.  8vo.  With  Illustrations.  Cloth, 
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6 

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TRANSACTIONS   OF  THE    NEW   YORK  STATE    MEDICAL  ASSOCIA- 

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phael, M.  D.     8vo.     Cloth,  $4.00 ;  sheep,  $5.00. 

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Crookes.     With  336  lUustrations.     8vo.     Cloth,  $5.00. 

WALTON  (GEORGE  E.).  Mineral  Springs  of  the  United  States  and  Canadas. 
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WEBBER  (S.  G.).  A  Treatise  on  Nervous  Diseases:  Their  Symptoms  and 
Treatment.    A  Text-Book  for  Students  and  Practitioners.   8vo.   Cloth,  $8.00. 

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Questions  for  Review  and  Examination,  and  Vocabulary  of  Medical  Terms. 
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WELLS  (T.  SPENCER).    Diseases  of  the  Ovaries.     8vo.     Cloth,  $4.50. 

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